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[. Technical Note N-1213

S CORROSION OF MATERIALS IN SURFACE SEAWATER

AFTER 12 AND 18 MONTHS OF EXPOSURE

By

Fred M. Reinhart and James F. Jenkins

January 1972

Approved for public release;distribution unlimited

NAVAL CIVIL ENGINEERING LABORATORYPort Hueneme, California 93043

.t.p d-.eJ by

NATIONAL TECHNICALINFORMATION SERVICE

C' CT--ei INS~nIedVA 22151

TI

; • ORROIONOF MTERALS N SUFAC SEAATE

CORROSION OF MATERIALS IN SURFACE SEAWATER AFTER 12 AND 18 MONTHS OF

EXPOSURE

Technical Note N-1213

YF 38.535.005.01.004

by

Fred M. Reinhart and James F. Jenkins

ABSTRACT

A total of 1150 specimens of 189 different alloys were completelyimmersed in surface seawater for 12 and 18 months to obtain data forcomparison with deep ocean corrosion data.

Corrosion rates, types of corrosion and pit depths were determined.Some highly alloyed nickel alloys, titanium alloys, silicon cast

irons, specialty stainless steels, columbium, tantalum and a tantalum-tungsten alloy were uncorroded in seawater both at the surface and atdepth.

The corrosion rates of the copper base alloys, nickel base alloys,steels, cast irons, lead, tin, lead-tin solder, molybdenum and tung-

sten decreased with the concentration of oxygen in seawater, i.e., the

corrosion rates were lower at depth than at the surface. The corrosion

rates of Ni-200, Ni-Cu 402, 406, 410, K-500 and 45-55, Ni-Cr-Fe X750,Ni-Mo2, all steels, grey cast iron and alloy cast irons decreased

linearly with the concentration of oxygen in seawater.The copper base alloys, steels, cast irons, molybdenum, tungsten,

lead and lead-tin solder corroded uniformly both at the surface and atdepth.

The aluminum alloys were attacked by pitting and crevice corrosion

and seawater was more aggressive at depth than at the surface for such

alloys. The effect of the concentration of oxygen in seawater on the

corrosion of aluminum alloys was inconsistent.The stainless steels were attacked by pitting, tunneling and crev-

ice corrosion, except 309, 316L, 317, 329, 633, 20Cb-3 and Ni-Cr-Mo-Si.Surface seawater was more aggressive than seawater at depth in promot-

ing these types of corrosion on the stainless steels.

Approved for public release; distribution unlimited

i' I i ido

!E Gi_!

PREFACE

The Naval Civil Engineering Laboratory has been conducting aIresearch program to determine the effects of deep ocean environmentson materials. It is expected that this resaarch will establish thebest materials to be used in deep ocean construction.

A Submersible Test Unit (STU) was designed, on which many testspecimens can be mounted. The STU can be lowered to the ocean floor I

and remain there for long periods of exposure.Thus far, exposures have been made at two deep-ocean test sites

and at a surface seawater site in the Pacific Ocean. Seven STUs havebeen exposed and recovered. Test Site I (nominal depth of 6,000 feet)is approximately 81 nautical miles west-southwest of Port Hueneme,California, latitude 33*44'N and longitude 120*45'W. TesL Site II(nominal depth of 2,500 feet) is 75 nautical miles west of Port Hueneme,California, latitude 34*06'N and longitude 120*42'W. A surface sea-water exposure site (V) was established at Point Mugu, California,(latitude 34*06'N and longitude 119*07'W) to obtain surface immersiondata for comparison purposes.

This report presents the results of the evaluation of the differ-

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Naval Civil Engineering Laboratory Unclass'.fiedPort Hiueneme, California 93043

A MICRO? -TLC.

CORROSION OF MATERIALS IN SURFACE SEAWATER AFTER 12 AND 18 MONTHSOF EXPOSUREa CaTiCS.&,o .. etgs (Type. @1,i. d 1C.u1.41. doet)e

Final - June 1966-June 1971

Fred M. Reinhart and James F. Jenkins

si )IOV0.1? C.n. To-,L .0 O- -. 092 1. No OP 4reP

January 1972 103 10&a CONACA T VOR GRANT No Ae RJNVA *AA 11AS

G. Ra*.%cVNO.YF 38.535.005.01.004 Technical Note N-1213

a. OV.AIA I V.*IS. (Any attar .I,tob-y that may 0. SCCiCW.

Approved for public release; distribution unlimited

Naval Facilities Enginettring

Command

Atotal of 1150 specimens of 189 different alloys were completelyimmersed in surface seawater for 12 and 18 months to obtain data forcomparison with deep ocean corrosion data.

Corrosion rates, types of corrosion and pit depths were determinedSome highly alloyed nickel alloys, titanium alloys, silicon cast

irons, specialty stainless steels, columbium, tantalum and a tantalum-tungsten alloy were uncorroded in seawater both at the surface and atdepth.

The corrosion rates of the copper base alloys, nickel base alloys,steels, cast irons, lead, tin, lead-tin solder, molybdenum and tung-sten decreased with the concentration of oxygen in seawater, i.e.,the corrosion rates were lower at depth than at the surface. Thecorrosion rates of Ni-200, Ni-Cu 402, 410, K-500 and 45-55, Ni-Cr-FeX750, Ni-Mo2, all steels, grey cast iron and alloy cast irons de-creased linearly with the concentration of oxygen in seawater.I

The copper base alloys, steels, cast irons, inolybdenum, tungsten,lead and lead-tin solder corroded uniformly both at the surface and ai

depth. Continued

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Corrosion

Metals

Alloys

Sea water

Shallow water

Nickel Alloys

Titanium Alloys

Silicon cast irons

Stainless steels

Columbium

Tantalum

Tantalum-tungsten alloy

Copper alloys

Lead

rin

Lead-tin solder

Molybdenum

Tungsten

Steels

Cast iron

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The aluminum alloys were attacked by pitting and crevice corrosionand seawater was more aggressive at depth than at the surface for suchalloys. The effect of the concentration of oxygen in seawater on thecorrosion of aluminum alloys was inconsistent.

The stainless steels were attacked by pitting, tunneling and crevicecorrosion, except 309, 316L, 317, 329, 633, OCb-3 and Ni-Cr-Mo-Si.Surface seawater was more aggressive than seawater at depth in promot-ing thesc types of corrosion on the stainless steels.

//I

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INTRODUCTION

The development of deep diving vehicles which can stay submergedfor long periods of time has focused attention on the deep ocean as anoperating environment. This has created a need for information con-cerning the behavior of both common and potential materials of construc-tion at depths in the ocean.

To study the problems of construction in the deep ocean, project"Deep Ocean Studies" was established. Fundamental to the design, con-"struction and operation of structures, and their related facilities,is information with regard to the deterioration of materials in deepocean environments. This portion of the project is concerned withdeterminirg the effects of these environments on the corrosion of

metals ard alloys.In order tr determine the differences between the corrosiveness of

seawater at depths and at the surface it is desirable to compare deepocean corrosion data with surface immersion data. Since surface datawas not available in the literature for many of the alloys exposed at

depths in the Pacific Ocean, it was decided to establish a surface ex-posure site to obtain this information. Therefore, a third site, des-ignated at Site V, was established at Point Mugu, California, latitude34*06'N and longitude 11907'W.

The locations of the thrce test sites, two deep ocean sites andthe surface site, are shown in Figure 1. The specific geographicallocations of the test sites and the average characteristics of the sea-water at these sites are given in Table 1.

Reports pertaining to the performance of alloys in the deep oceanenvironments are given in References 1 through 9.

This report presents a discussion of the results obtained of thecorrosion of various alloys exposed at the surface, Site V, for periodsof 12 and 18 months.

RESULTS AND DISCUSSIONS

The results presented and discussed herein also include the corro-sion data for the alloys exposed at the surface for the InternationalNickel Company, Inc. Permission for their use has been granted by

I. Dr. T. P. May, Reference 10.J The deep ocean data for de~ths of 2,500 and 6,000 feet after com-

parable periods of exposure are included for comparison purposes.

Th epoendt o etso 250ad600fe fe on(I

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ALUMINUM ALLOYS

The chemical compositions of the aluminum alloys are given inTable 2 and their corrosion rates and types of corrosion in Table 3.The variations of the corrosion rates and maximum pit depths of thealloys with depth and with oxygen content of seawater are shown graphi-cally in Figures 2 through 9.

Aluminum alloys corrode chiefly by the pitting and crevice typesin seawater, both of which are localized types, which means that thegreater portion of the surface area of a specimen is unattacked. There-fore, corrosion rates calculated from weight losses and expressed asmile per year, which indicates uniform thinning of the material, arevery misleading because they create an erroneous impression of the be-havior of the material. In order to present a more realistic pictureof the behavior of aluminum alloys, the maximum and average pit depthsand the maximum depth of crevice corrosion are also reported.

In Figure 2 the corrosion rates of the aluminum alloys versusdepth are shown. The variation of the oxygen content of seawater withdepth is also shown in Figure 2. The corrosion rates of aluminum alloys1100-H14, 5083-H113 and 3003-H14 increase progressively with depth.Those of the 6061-T6 and 2219-T81 alloys are greater at deptli than atthe surface but their increases are not progressive since their ratesat the 2,500-foot depth are greater than those at the 6,000-foot depth.The corrosion rate of 2024-0 at the 6,000-foot depth was greater thanat the surface, but at the 2,500-foot depth it was less than at thesurface. The corrosion rate of 5086-H34 decreased slightly with depth.It is shown in Figure 2 that based on corrosion rates the corrosion of5083-H113, 1100-H14 and 3003-H14 aluminum alloys are depth dependent.

The corrosion rates of aluminum alloys 2219-T81 and 6061-T6 in-creased with the decreasing concentration of oxygen in seawater whilethose of 5086-H34 decreased slightly as shown in Figure 3.

The corrosion rates of aluminum alloys 1100-H14, 3003-H14, 2024-0and 5083-H113 are independent of the concentration of oxygen in sea-water as shown in Figure 4. The corrosion rates of three of thesealloys, 1100-H14, 3003-H14 and 5083-H113, were shown to be depth (pres-sure) dependent, Figure 2.

The maximum depths of pits of aluminum alloys 3003-H14, 2024-0 and5083-H113 increased with depth (pressure), i.e., they were pressuredependent as shown in Figure 5. The maximum depths of pits of alloy5086-H34 decreased with increase in depth. Although those of alloys2219-T81 and 6061-T6 were deeper at a depth of 6,000 feet than at thesurface, the depths of pits were at the maximums at the 2,500-footdepth, Figure 5.

The maximum depths of pits of aluminum alloys 2024-0, 2219-T81and 6061-T6 increased as the concentration of oxygen in seawater de-creased, while those of 5084-H34 !c-reased with the concentration ofoxygen, Figure 6.

2

"The maximum depths of pits in aluminum alloys 3003-H14 and 5083-H113 were independent of the concentration of oxygen in seawater, Figure7. The maximum pit depths of these two alloys were depth (pressure)dependent as shown in Figure 5.

The corrosion rates of 6061-T6 and the 5000 series alloys (5083,5086 and 5456) decreased with increasing time of exposure in surfaceseawater while their maximum pit depths increased with time of exposureas shown in Figure 8. The corrosion rates of alloys 3003-H14, Alclad3003-H12 and 2219-T81 did not decrease constantly with increasing timeof exposure in surface seawater; they decreased with time through 540days of axposure and thereafter increased sharply as shown in Figure 9.

The depths of the maximum pits in alloy 2219-T81 increased withtime of exposure, those in alloy 3003-H14 decreased initially and after400 days increased rapidly, Figure 9. The depths of the maximum pitsin Alclad 3003-H12 increased through the first 400 days of exposureand thereafter became constant with time. This constancy is explainedby the fact that the sacrificial protective alloy layers on the Alclad3003-H12 are corroded laterally, thus preventing pitting of the protec-ted core alloy.

The corrosion rates as well as the maximum pit depths of 6061-T6and 2219-T81 increased with decreasing concentration of oxygen in sea-

water, Figures 3 and 6. However, both the corrosion rates and maximum" pit depths of 5086-H34 decreased with the concentration of oxygen in

seawater. Although the maximum pit depths of 2024-0 increased withdecreasing concentration of oxygen in seawater, Figure 6, its corrosion

rate appears to be affected to a much lesser extent by changes in theconcentration of oxygen in seawater, Figure 4. Neither the changes inthe corrosion rates nor the maximum pit depths of aluminum alloys 3003-H14 and 5083-H113 appear to be dependent upon the changes in the concen-tration of oxygen in seawater as shown in Figures 4 and 7. They aregenerally greater at the lower concentrations of oxygen, although notprogressively. The ccrrosion rates of aluminum alloys 1100-H14, 3003-H14 and 5083-HI13 were depth (pressure) dependent in that they increasedwith depth, Figure 2, while those of 5086-H34 alloy decreased slightlywith increasing depth. The corrosion rates of aluminum alloys 6061-T6,2024-0 and 2219-T81 were not consistently influenced by depth, Figure 2.The maximum pit depths of four alloys, 5083-HI13, 2024-0, 5086-H34 and3003-H14 appear to have been affected by depth; those of 5083-H113,2024-0 and 3003-H14 increased with depth while those of 5086-H34 de-creased with increasing depth, Figure 5. The maximum pit depths ofalloys 2219-T81 and 6061-T6 were not consistently affected by depthexcept that their maximum pit depths at a depth of 6,000 feet weredeeper than at the surface. In general, the corrosion rates of thealuminum alloys decreased with increasing time of exposure in surfaceseawater while the maximum depths of the pits increased with time ofexposure, Figures 8 and 9.

3

COPPER ALLOYS

The chemical compositions of the copper alloys are given in Table4 and their corrosion rates in Table 5. The effects of depth, concen-tration of oxygen in seawater and time on the corrosion rates areshown graphically in Figures 10 through 12.

Copper alloys corrode uniformly, hence corrosion rates calculatedfrom weight losses and reported as mils per year reflect the true con-dition of the alloys. Therefore, corrosion rates for the copper alloyscan be used reliably for design purposes. However, this does not applyto the copper base alloys which are susceptible to parting corrosion.

The variation of the corrosion rates of copper and the copperalloys with depth in the Pacific Ocean are shown in Figure 10. Sincethe corrosion rates of all the copper alloys, except those attacked byparting corrosion, were so comparable, the average values were plottedin Figure 10. The corrosion of copper was insensitive to depth as wellas to the changes of concentration of oxygen in seawater at depth asshown in Figure 10. The oxygen concentration curve was included inFigure 10 to show its variation with depth and to show whether the cor-rosion rate curves were of comparable shape. The average corrosionrate curve for the copper alloys, although showing a slight decreasewith depth, did not decrease gradually; hence it is more oxygen thandepth dependent. The corrosion rates of only oxue alloy, Nickel-Silver#752, increased gradually with increasing depth, Figure 10; hence itscorrosion is mostly depth dependent.

The corrosion of copper was independent of the concentration ofoxygen in seawater as shown in Figure 11. However, the corrosion ofthe copper alloys decreased slightly with decreasing concentration ofoxygen in seawater.

The corrosion rates of copper and the copper alloys decreased withincreasing time of exposure in surface seawater as shown in Figure 12.

The following alloys were attacked by parting corrosion in sea-water: commercial bronze, red brass, Muntz metal, manganese bronze Aand nickel-manganese bronze, containing from 10 to 42 percent zinc,were dezincified; aluminum bronzq, containing 5, 7, 10, 11 and 13 per-cent aluminum were dealuminified.

NICKEL ALLOYS

The chemical compositions of the nickel and nickel alloys aregiven fn Table 6 and their corrosion rates and types of corrosion inTable 7. The effects of depth, concentration of oxygen in seawaterand time are shown graphically in Figures 13 to 19.

In stagnant seawater and underneath fouling many of the nickelalloys are attacked by pitting and crevice corrosion in addition togeneral surface attack. Under the same conditions some of the more

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highly alloyed nickel alloys are immune to corrosion, such as Ni-Cr-Fe718, Ni-Cr-Mo 3 and 625, Ni-Mo-Cr "C", and Ni-Cr-Fe-Ho "F", "G" and "X".Ni-Co-Cr-Mo 700 alloy was attacked only by incipient crevice corrosionafter 400 days of exposure at a depth of 2,500 feet.

The effect of depth on the corrosion of nickel alloys is shown inFigures 13, 14 and 15, The corrosion rates of alloys Ni-Cr-Fe 610 (cast)and 88 decreased with increasing depth, Figure 14. The corrosion ratesof alloys Ni-Cu 400, Ni-Cr 75, 65-35 and 80-20, and Ni-Cr-Ee 600 and X750decreased from the surface to the 2,500-foot depth and remained constantto the 6,000-foot depth,Figures '3, 14 and 15. All the other alloys ex-cept Ni-Sn-Zn 23 and Ni-Si D were more affected by the oxygen concentra-tion than by depth. The corrosion rates of Ni-Sn-Zn 23 and Ni-Si D al-loys were higher at the 6,000-foot depth than either at the surface or atthe 2,500-foot depth, showing that neither depth nor oxygen were exertingthe major influence on the corrosion of these two alloys.

The effect of the concentration of oxygen in seawater on the cor-rosion rates of nickel alloys is shown in Figures 16, 17 and 18. Thecorrosion rates of alloys electrolytic nickel, Ni-200, 201, 210, 211and 301, Ni-Cu 402, 406, 410, K500, K505 and 45-55, Ni-Cr-Fe X750,Ni-Mo-Fe "B", Ni-Cr 80-20, and Ni-Mo 2 decreased with decreasing con-centration of oxygen in seawater as shown in Figures 16, 17 and 18.The corrosion rates of some alloys decreased with the oxygen concentra-tion to about 1.35 ml per liter and thereafter remained constant to0.4 ml per liter - alloys Ni-Cu 400, NI-Cr-Fe 600 and Ni-Cr 75. Thecorrosion of alloys Ni-Sn-Zn 23 and Ni-SiD are apprently not affectedto any major extent by the concentration of oxygen in seawater, Figures17 and 18.

The effect of time on the corrosion rates of some nickel alloys insurface seawater is shown in Figure 19. The corrosion rates of alloysNi-200, Ni-Cu 400, Ni-Cr-Fe 600 and X750, and Ni-Fe-Cr 902 decreasedwith increasing time of exposure.

In general, pitting and crevice corrosion were more rapid in sur-face exposure than at depth.

Welding Ni-200 with electrode No. 141 and filler metal 61 resultedin corrosion of the weld bead material and/or in the adjacent heataffected zone.

There was no accelerated corrosion of Ni-Cu 400 alloy or of theweld beads when welded with electrodes 130 and 180; however, weld beadsof filler metal 60 and electrode 190 were attacked locally.

The corrosion of Ni-Cu K500 alloy was noý affected by welding withelectrode 64 at the 2,500-foot depth, but the weld beads from electrodes64 and 134 were attacked during 540 days of exposure at the surface andthe weld bead of 134 electrode at the 2,500-foot depth.

The weld beads on Ni-Cr-Fe 600 alloy made from electrodes 132, 182,62 and 82 were selectively attacked during exposure at the surface andat the 2,500-foot depth except the bead from electrode 182 at the 2,500-foot depth which was only uniformly etched.

5

The weld beads on Ni-Cr-Fe 718 alloy made from 718 electrodes wereuncorroded.

The weld beads on Ni-Cr-Fe X750 alloy made from electrodes 69 and718 were selectively corroded during exposure at the surface and atthe 2,500-foot depth, excert the bead made from electrode 69 at the2,500-foot depth.

The weld beads on Ni-Cr-Mo 625 alloy made with 625 electrodes wereuncorroded.

The weld beads on NI-Fe-Cr 800 alloy made with electrodes 82 and138 were selectively attacked during exposure at the surface and at the2,500-foot depth.

The weld beads on Ni-Fe-Cr 825 alloy made with electrode 135 wereselectively attacked while weld beads made with electrode 65 were un-attacked at the 2,500-foot depth and only by incipient pitting at thesurface.

STEELS

The chemical compositions of the steels are given in Table 8 andtheir corrosion rates and types of corrosion in Table 9. The effectsof depth, concentration of oxygen in seawater and time are shown graphi-cally in Figures 20 to 22.

Since the corrosion rates of the iteels were nearly the same atany one depth, the average values for any one depth were averaged andplotted in Figures 20 to 22.

The effect of depth on the average corrosion rate of the stool1s isshown in Figure 20. The vdiiaLion of the concentration of oxygen inseawater with depth is also plotted in Figure 20 foz .;omparison purposes.The shapes of the curves for the steels and AISI 1010 steel show thatthe corrosion rates are not depth (pressure) dependent. The shapes ofthose curves are practically the same as the shape of the oxygen curve,indicating that the concentration of oxygen exerts a major influence onthe corrosion of steels in seawater.

The effect of the concentration of oxygen in seawater on the corro-sion rates of steels is shown in Figure 21. The curve for the averagecorrosion rates of Ail the steels is a straight line, indicating thatthe corrosion rates of steels in seawater are proportional to the oxy-gen concentration.

The corrosion rate of AISI 1010 steel and the averages of the cor-rcsion rates of all the carbon and low alloy steels after one year ofexposure versus the oxygen content and the temperature of seawater were

analyzed using the technique of linear regression analysis. By thistechnique a relationship between oxygen content, temperature and cor-rosion rate was obtained for both the average of all carbon and lowalloy steels and for AISI 1010 steel. The derived formulae are:

6

Corrosrun rate (MPY) - 0.84 + 1.0 (02) + 0.014 (T)

t (avg of carbon andlow alloy steels)

Corrosion Rate (MPY) 0.19 + 1.1 (02) + 0.1 (T)

(AISI 1010)

The corrosion rates are in mils per year (HPY), the oxygen content ofseawater in milliliters per liter (ml/i) and temperature in degreesCentigrade (0 C).

These derived formulae illustrate two important points:

(1) The concentration of oxygen in seawater is a major vari-able and its effect on the corrosion rate of steel in seawater is

linear.

(2) The temperature of the seawater has less effect on the

corrosion of steel in seawater than the oxygen content and its effectis also linear.

Theie formulae, however, cannot be used to predict the corrosionrates of steels in seawater at other locations due to the influences ofother variables such as time, currents, sediment effects, etc. Forexample, the above formulae are not satisfactory for predicting cor-rosion rates for steels in the Tongue-of-the-Ocean, Atlantic Ocean.Since they are not applicable, it is obvious that other variables inthat location are different from those in the Pacific Ocean off theChannel Islands.

The effect of time of exposure in surface seawater on the averagecorrosion rates of steels is shown in Figure 22. The corrosion ratesdecrease parabolically with increasing time of exposure.

All the steels except AISI Type 502, in general, corroded uniformlyexce'nt for some pitting in surface seawater which was caused by fouling.AISI iype 502, because it contained about 5 percent chromium, was pit-ted.

CAST IRONS

The chemical compositions of the cast irons are given in Table 10and their corrosion rates and types of corrosion in Table 11. Theeffects of depth, concentration of oxygen in seawater and time are showngraphically in Figures 23 to 25.

The effect of depth on the corrosion rates of the cast irons isshown iii Figure 23. The shape of the corrosion tate curve for the alloy

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cast irons was very close to that of the oxygen curve and shows thatthe corrosion of the alloy cast irons is not depth dependent. Theshapes of the curves for gray cast iron, the austenitic cast irons, andthe silicon and silicon-molybdenum cast irons show that depth is not animportant variable in their corrosion behavior.

The effect of the concentration of oxygen in seawater on the cor-rosion rates of cast irons is shown in Figure 24. The corrosion ratesof gray cast iron and the alloy cast irons decreased practically line-arly with the concentration of oxygen in seawater. The corrosion ratesof the austenitic cast irons decreased with the concentration of oxygenin seawater while the silicon and silicon-molybdenum cast irons wereuncorroded; hence were insensitive to the concentration of oxygen.

All the cast irons corroded uniformly except the silicon andsilicon-molybdenum cast irons which were uncorroded.

The effect of time of exposure on the corrosion of cast ironsduring surface exposure in seawater is shown in Figure 25. Data wereavailable for only two austenitic cast irons and their corrosion ratesdecreased asymptotically with increasing time of exposure. Their cor-rosion rates became practically constant at between 2 and 3 mils peryear after about two years of exposure.

STAINLESS STEELS

The chemical compositions of the stainless steels are given inTable 12 and their corrosion rates and types of corrosion in Tables 13through 17. The effect of depth and the concentration of oxygen inseawater on the corrosion rates of stainless steels are shown graphi-cally in Figures 26 through 31.

In general, stainless steels corrode chiefly by pitting and crevicecorrosion in seawater. In these types of localized attack the majorityof the surface area is unattacked so that corrosion rates calculatedfrom weight losses are very misleading because they reflect a uniformthinning of the material. However, in spite of this, the corrosionrates of a number of the stainless steels were plotted versus depthand the concentration of oxygen in seawater to see if any informationof value could be obtained.

The corrosion rates of the 200 and 400 Series stainless steels asaffected by depth are shown in Figure 26. The corrosion rates of AISI430 and 18Cr-14Mn-0.5N stainless steels decreased with increasing depth.The corrosion rates of AISI 201, 202, 410 and 446 were lower at depththan at the surface, but they did not decrease progressively with in-creasing depth.

The effects of changes in the oxygen concentration of seawater onthe corrosion rates of the 200 and 400 Series stainless steels areshown in Figure 27. The corrosion rates of AISI 410 decreased linearlywith the oxygen content while those for AISI 201, 202 and 446 were not

8

uniformly decreased. The corrosion rates of AISI 430 and 18Cr-14Mn-0.5N stainless steels, although lower at the lower oxygen concentra-

tions than at the highest oxygen concentration, were not uniformlyaffected by the oxygen concentration.

Examination of the pitting, tunnelinq and crevice corrosion datafor these stainless steels in Tables 13 and 17 shows only a generalrelationship with corrosion rates. Th( -pes of corrosion were, ingeneral, more severe or just as severe ae surface seawater (high-est oxygen concentration) than at depths ot 2,500 and 6,000 feet.However, it is more realistic to assess the performance of thesestainless steels on their localizpd types of corrosion performancethan upon calculated corrosion rates.

The corrosion rates of the 300 Series stainless steels as affec-ted by depth are shown in Figure 28. Only the corrosion rates of theAISI 304 and 304L stainless steels decreased with increasing depth.The corrosion rates of AISI 301, 302, 316, 316 (sensitized), 330, 347,304 (sensitized) and 325 stainless steels were lower at depth than atthe surface, but they did not decrease progressively with increasingdepth. In addition, the shape of the corrosion rate curve for AISI325 was similar to the oxygen concentration curve.

The effect of changes in the concentration of oxygen in seawateron the corrosion rates of the 300 Series stainless steels are shown inFigure 29. The corrosion rates of the alloys shown in Figure 29 de-creased with decreasing oxygen concentration, although not uniformly.

Examination of the pitting, tunneling and crevice types of corro-sion in Table 14 for the alloys whose corrosion rates were plotted inFigures 28 and 29 shows that, in general, there is no definite correla-tion between their cotrosion rates and the severity of these types ofcorrosion. For example, the corrosion rates of AISI 304L varied from1.0 co 0.4 to <0.i MPY at the three depths, while pitting corrosionwas to perforation (115 mils) in all exposures while crevice and tun-neling corrosion was more severe at the 6,000-foot depth where thecorrosion rate was the lowest (<0.1 MPY).

Oxygen and depth apparently had no effect on the corrosion of thefollowing 300 Series stainless steels: AISI 309, 310, 311, 316L, 317,"321 (slightly affected) and 329.

The effect of depth on the corrosion rates of some of the 600Series precipitation hardening stainless steels is shown in Figure 30.The corrosion rate of 631-THI050 and 635 decreased with increasingdepth of seawater. The corrosion rates of 630-H925 and 632-RHI100 werelower at depth than at the surface but they did not decrease progress-ively with increasing depth.

The effect of changes in the concentration of oxygen in seawateron the corrosion rates of the 600 Series precipitation hardening stain-less steels is shown in Figure 31. The corrosion rate of AISI 632-.RH1100 decreased progressively with the oxygen content of seawater.

The corrosion rates of AISI 630-H925, 631-TH1050 and 635, although

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lower at the lower oxygen concentrations than at the highest, did notdecrease progressively with the oxygen concentration.

Here again, comparison of the corrosion rates with the severity ofthe pitting, tunneling and crevice types of corrosion (Table 6) showedno definite correlations.

The corrosion rates and types of corrosion of the miscellaneouscast and wrought stainless steels are given in Table 17. Except forthe 18Cr-14Mn-O.SN which contained no nickel, the others containedgreater percentages of chromiun and nickel than the conventional stain-less steels in addition to molybdenum and copper. The corrosion ratesof these stainless steels were mostly less than 0.1 MPY and instancesof pitting and crevice corrosion were few except for the l8Cr-15Mn-0.5Nalloy. Significant pitting and crevice corrosion occurred during sur-face exposures of wrought alloy 20-Cb and cast alloy Ni-Cr-Cu-Mo #2.

TITANIUM ALLOYS

The chemical compositions of the titanium alloys are given inTable 18 and their corrosion rates and types of corrosion in Table 19.

There was no corrosion of any of the alloys except the welded13V-IlCr-3AI alloy. It was susceptible to stress corrosion crackingduring surface exposures. Specimens were in two welded conditions,half were butt welded and a 3-inch diameter circular weld bead wasplaced on the other half of the specimens. The welded specimens wereintentionally not stress relieved in order to retain the maximum in-ternal welding stresses in the specimens during exposure. The stresscorrosion cracks extended across the butt welds normal to the directionof the beads and developed within 398 days of exposure. The stresscorrosion cracks in the specimens with the circular welds extendedradially across the weld beads and they also developed within 398 daysof exposure.

MISCELLANEOUS ALLOYS

The chemical compositions of the miscellaneous alloys are given inTable 20 and their corrosion rates and types of corrosion in Table 21.The effect of depth, concentration of oxygen in seawater and time areshown in Figures 32 to 34.

Columbium, tantalum and tantalum alloy Ta60 were uncorroded during763 days of exposure at the surface and 402 days of exposure at a depthof 2,500 feet.

The effect of depth on the corrosion rates of the miscellaneousalloys is shown in Figure 32. The corrosion rates of tin, molybdenumand tungsten decreased with increasing depth. The corrosion rates oflead and lead-tin solder were lower at depth than at the surface but

10

S~did not decrease progressively with increasing depth. The corrosion :

S~rate of zinc, on the other hand, was much greater at the 6,000-foot•: depth than at either the surface or the 2,500-foot depth.

S~The effect of the concentration of oxygen in seawater on the cor-• rosion rates of the miscellaneous alloys is shown in Figure 33. TheS~corrosion rates of lead, tin, lead-tin solder, molybdenum and tungstenr ~were lower at the lower oxygen concentrations than at the highest, but= the decreases were not linear. Since there were only two points for

S~the molybdenum and tungsten curves, there is no assurance that the•-- curves would be linear with more points at intermediate oxygen concen-

trations. The corrosion rate for zinc was definitely not dependentupon the oxygen concentration of seawater; it was the same at the low-est as at the highest concentration of oxygen in seawater and twice ashigh at the intermediate oxygen concentration.

The effect of time of exposure at the surface on the corrosion rateS~of molybdenum and tungsten are shown in Figure 34. The corrosion rateS~of molybdenum decreased with increasing time of exposure while that of£ tungsten definitely increased.

SUMMARY

S~The purpose of this investigation was to determine the effects ofsurface seawater on the corrosion of different types of alloys for com-parison with their deep ocean corrosion behavior. To accomplish this1,134 specimens of 189 different alloys were exposed 5 feet below thelowest tide level in the Pacific Ocean at Point Mugu, California (SiteV, Figure 1) for from 366 to 763 days.

Aluminum Alloys

SIn general the corrosion rates of the aluminum alloys were greaterSat depth than at the surface in the Pacific Ocean after one year of

€?exposure, except for 5086-H34 whose corrosion rate was slightly lower.SThe maximum pit depths of the aluminum alloys were greater at depth

Sthan at the surface, except for 5086-H34 whose maximum pit depths wereS less than at the surface.

S~The corrosion rate of 5086-H34 decreased slightly with the oxygenS~concentration of seawater, those of 2219-T81 and 6061-T6 increased withS~decreasing oxygen concentration and those of 1100-H14, 5083-H113 andS~3003-H14 were higher at the lower oxygen c:oncentrations, but not pro-S~gressively. The corrosion rate of 2024-0 appears to be independent ofS~the oxygen concentration of seawater.

tThe maximum pit depths of alloys 2024-0, 2219-T*81 and 6061-T6 in-Screased with decreasing concentration of oxygen in seawater, while those!of 5086--H34 decreased with the oxygen concentration. The maximum pit,•depths of 3003-H14 were deeper at the lower oxygen concentrations, but

LI

4did ot ecraseproressvel wih icresingdeph. he orrsio

rateof incon he oherhand wa muc graterat he 6000foo

detIhna ihrtesraeo h ,0-otdph I

not progressively. The maximum pit depths of 5083-H113 were apparentlynot dependent upon the oxygen concentration.

The corrosion rates of the 5000 Series aluminum alloys and 6061-T6decreased with increasing time of exposure at the surface in the PacificOcean while their maximum pit depths increased. The corrosion ratesof 2219-T81, 3003-H14 and Alclad 3003-H12 decreased with time of exposureat the surface through 540 days of exposure and thereafter, for some un-known reason, increased rapidly. Their maximum pit depths, in general,increased with time of exposure.

The aluminum alloys were attacked by pitting and crevice types ofcorrosion; hence, corrosion rates calculated from weight losses are un-suitable for assessing the corrosion behavior.

Crevice corrosion, in general, was more severe at depth than atthe surface.

Copper Alloys

The copper alloys, in general, corroded uniformly except for someisolated cases of pitting and cratering. Also, there was dezinclfica-tion of Muntz metal and nickel-manganese bronze and dealuminificationof the aluminum bronzes.

The corrosion rate of copper was essentially unaffected by depthand that of all the copper alloys was lower at depth than at the sur-face, but not progressively.

The corrosion rate of copper was unaffected by changes in the con-centration of oxygen in seawater while the average rate of the copper

alloys decreased with decreasing concentration of oxygen. Tne corro-sion rate of Muntz metal, which also was dezincified, also decreasedwith the concentration of oxygen in seawater.

The corrosion rates of all the copper alloys decreased with in-

creasing time of exposure at the surface except Muntz metal whose cor-rosion rate increased with time.

Nickel Alloys

Fourteen (14) of the nickel base alloys were uncorroded: Ni-Cr-Fe 718, Ni-Cr-Mo 3, Ni-Cr-Mo 625, Ni-Fe-Cr 800, Ni-Fe-Cr 804, Ni-Fe-Cr825, Ni-Fe-Cr 825 (sensitized), Ni-Fe-Cr 825Cb, Ni-Fe-Cr 901, Ni-Cr-Fe-Mo "F", Ni-Cr-Fe-Mo "G", Ni-Cr-Fe-Mo "X", NI-Mo-Fe "B", and Ni-Mo-Cr "C".

The corrosion rates of the other nickel base alloys were higher atthe surface than at depth. The corrosion rates of Ni-Cr-Fe 600 and Ni-Cr-Fe 88 decreased with increasing depth while those of the other alloysdid not decrease progressively with depth.

Most of the alloys which were corroded were also attacked by crev-ice corrosion.

The corrosion rates of all except two nickel base alloys (Ni--Sn-Zn 23 and Ni-Si D) decreased with decreasing concentration of oxygen in

12

kL_,

seawater. The corrosion rates of Ni-Cr-Fe X750, Ni-Mo 2, Ni-200 andNi-Cu 402, 406, 410, K500, K505 and 45-55 alloys decreased linearlywith the concentration of oxygen in seawater.

The corrosion rates of Ni-200, Ni-Cu 400, Ni-Cr-Fe 600 and X750,and Ni-Fe-Cr 902 decreased with increasing time of exposure at thesurface.

In general, pitting and crevice corrosion were more rapid in sur-face seawater exposure than at depth.

There was either no corrosion or uniform corrosion of weld beads andin the adjacent heat affected zones when Ni-Cu 400 alloy was welded

t with electrodes 130 and 180, Ni-Cr-Fe 718 with electrode 718, and Ni-Cr-Mo 625 with electrode 625.

There was selective corrosion, line corrosion or pitting of eitherthe weld beads or in the adjacent heat affected zones or both when Ni-200 was welded with electrodes 61 and 141, Ni-Cu 400 with electrodes 60and 190, Ni-Cu K500 with electrodes 64 and 134, Ni-Cr-Fe 600 with elec-trodes 62, 82, 132 and 182, Ni-Cr-Fe X750 with electrodes 69 and 718,

L Ni-Fe-Cr 800 with electrodes 82 and 138, and Ni-Fe-Cr 825 with elec-trodes 65 and 135.

Steels

nTe steels were all corroded uniformly and their corrosion rateswere comparable - carbon steels, low alloy-high strength steels, nickelsteels, and the very high strength steels.

The corrosion rates of the steels were lower at depth than at thesurface, but they did not decrease progressively with increasing depth;i.e., they were not depth dependent.

The average corrosion rates of all the steels decreased linearlywith the concentration of oxygen in seawater.

The corrosion rates, the oxygen concentration and temperature ofseawater were analyzed using linear regression analysis. The follow-ing relationships were obtained for AISI 1010 steel and the averagesof the other steels:

Corrosion Rate (MPY) - 0.84 + 1.0 (02) + 0.014 (T)

(Avg of carbon andlow alloy steels)

Corrosion Rate (MPY) - 0.19 + 1.1 (02) + 0.1 (T)

(AISI 1010)

The corrosion rates are in mils per year (MPY), the oxygen contentof seawater in milliliters per liter (ml/l) and temperature in degreesCentigrade (C).

13

/

These derived formulae illustrate two important points:

(1) The concentration of oxygen in seawater is a major vari-able and its effect on the corrosion rate of steel in seawater is linear.

(2) The temperature of seawater has less effect on the corro-sion of steel in seawater than the oxygen content and its effect is alsolinear.

These formulae, however, cannot be used to predict the corrosionrates of steels in seawater at other locations due to the influence ofother variables such as time, currents, sediment effects, etc.

The corrosion rates of the steeis decreased progressively with in-creasing time of exposure in surface seawater.

Cast Irons

Silicon and silicon-molybdenum cast irons were uncorroded in sea-water at the surface and at depth in the Pacific Ocean after one yearof exposure.

The corrosion rates of the other cast irons were lower at depththan at the surface, but were not depth dependent.

The corrosion rates of the alloy cast irons and gray cast irondecreased linearly with the concentration of oxygen in seawater andthose of the austenitic cast irons progressively.

The corrosion ratesof two austenitic cast irons, Type 4 and TypeD-2C, decreased asymptotically with time of exposure at the surface inseawater.

Stainless Steels

The following stainless steels were attacked only by incipientcrevice corrosion after one year of exposure in seawater: AISI Type309, 316L, 317, 329 and 633, 20Cb3 and Ni-Cr-Mo-Si.

All the other stainless steels were attacked by pitting, tunnelingand crevice corrosion in various degrees of severity.

In general, the miscellaneous wrought and cast stainless steels,except the 18C-14Mn-O.5N steel, were less severely attacked than theothers.

Titanium Alloys

The titanium alloys, unwelded and welded, except the 13V-llCr-3A1alloy, were uncorroded. Welded 13V-IlCr-3AI titanium alloy was suscep-tible to stress corrosion cracking when the welding stresses were notrelieved by thermal treatment.

14

Miscellaneous Al loys

Columbium, tantalum ai-d tantalum-tungsten alloy Ta60 were uncor-roded. However, magnesium alloy FS-1 was practically disintegratedafter one year of exposure in seawater.

The corrosion of lead (antimonial chemical and tellurium), tin,zinc, lead-tin solder, molybdenum and tungsten were not depth dependent.

The corrosion rates of lead, tin, lead-tin solder, molybdenum andtungsten decreased with the concentration of oxygen in seawater whilethat of zinc was not dependent on the oxygen concentration.

The corrosion rate of molybdenum decreased with increasing time ofexposure in seawater at the surface while that of tungsten increased.

CONCLUSIONS

Seawater at depth in the Pacific Ocean at the NCEL test sites wasmore aggressive to aluminum alloys than was seawater at the surface

r after one year of exposure, except for 5086-H34 alloy whose corrosionrate was slightly lower at depth.

In general, the corrosion rates and maximum pit depths of thealuminum alloys increased with decreasing oxygen concentration of sea-water.

Aluminum alloys, because their modes of corrosion are the localizedpitting and crevice types, must be protected for seawater applicationsif reasonable service i1fe is desired. In general, aluminum alloyscould not be recommended for deep sea applications for periods longerthan three years if protective maintenance cannot be performed.

In most cases the copper base alloys corroded either at the samerates or slightly slower rates at depth than at the surface in seawater.Copper base alloys which are susceptible to dezincification and dealumi-nification are not recommended for seawater service. The other copperalloys corroded uniformly and can be recommended for seawater servicewhere their low corrosion rates can be tolerated.

The nickel base alloys which were not corroded in seawater can berecommended for seawater applications.

Nickel base alloys susceptible to crevice corrosion are not recom-mended for seawater applications unless satisfactory precautions can betaken to prevent this type of attack.

The use of welded nickel alloys for seawater applications can berecommended only for those alloys which are not preferentially attackedin either the weld beads or the adjacent heat affected zones or both.

Steels and cast irons, because they corrode uniformly, can be rec-ommended for seawater applications and their reliability can be increasedby the use of adequate protective measures.

The stainless steels, because of their susceptibility to crevice,pitting and tunnel corrosion, are not recommended for seawater applica-tions. Alloys 309, 316L, 317, 329, 633, 20Cb-3 and Ni-Cr-Mo-Si couldbe used for limited applications of not more than one year if adequateprotective measures are used.

15

10

Titanium alloys, except-welded 13V-llCr-3A1 alloy, are recomnmendedfor seawater applications.

Columbium, tantalum and tantalum alloy Ta60 are recommended forseawater service where the expense can be justified.

Magnesium alloy FS-1 is unsatisfactory for seawater applications.Molybdenum, tungsten and lead (chemical, antimonial and tellurium),

because of their low uniform corrosion, can be recommended for seawaterapplications where their mechanical and physical properties fulfill therequirements.

Tin, zinc and lead-tin solder are not recommended for seawaterservice. Zinc of special purity, however, is used as sacrificial anodesto protect more noble alloys in many seawater applications.

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Table 11. Corrosion of.Caat Irons in Sea Water

Exposure CorrosionDepth, Ratj) Corrosion

Alloy Days Ft MY Type(2) Source( 3 )

G (ray 366 5 2.6 C. I 'NCO ( 1o)(10)

;ray 402 2370 1.7 U IM 1)t Cray 403 6780 1.8 U INC) (10)

(10)Nickel 366 5 7.h C TNCO (10)Nickel 40(2 2370 1.5 t. 1NCO (10)Nickel 403 6780 2.9 U INCO

Ni-Cr 01 3hh 5 5.: U NCO (10)Ni-Cr Il 402 2370 1. UvNi-Cr "1 403 6780 1.7 INCO(10)

Ni-Cr #2 366 5 4.9 C INCO (10)Ni-Cr #2 4/02 2370 1.8 i INCO (10)Ni-Cr #2 403 h7RO 1.8 t' INCO (10)

Ductile 0l 366 5 6.2 CR(24m) INCO (10)Ductile #1 402 2370 1 1.9 t INCO (10)

Ductile 01 403 67801 3.4 C INCO (10)

' Ductile 112 366 5 7.1 r INCO (00)Ductile #2 402 2370 1.8 U INCO (10)

Ductile #2 403 h780 2.9 c INCO (10)Silicon 366 o. INCO(10)

"Silicon 402 2370 ,o. j NC ICO (10)

Silicon 4U3 6780 -0.1 NC INCO (10)

i-.c 366 5 -O. ET INCO (10)

S1-Mo 402 2)370 NC I\CO (I0)-0.1 (10)

Si-mo 403 6780 ) 0.1 NC INCO (10)

Austenitic. Type 1 366 5 2.7 U INCO (10)

Austenitic, Type 1 I 402 2370 1.5 U INCO (10)Austenitic, Type 1 403 6780 1.0 V INCO (10)

Austenitic, Type 2 366 5 2.9 v INCO (10)Austenitic, Type 2 402 2370 1.1 U INCO

1. Austenitic, Type 2 403 6780 2.2 U INCO (10)

I-

[- 47

/

Table 11. (cont'd)

Exposure CorrosionDepth, Rate Corrosion

Alloy Days Ft MPY( 1 ) Type( 2 ) Source(3)

Austenitic, Type 3 366 5 2.8 U INCO( 10 )Austenitic, Type 3 402 2370 0.6 U INCO( 10 )Austanitic, Type 3 403 6780 1.8 U INCO(10)

Austenitic, Type 4 366 5 2.4 U INCO( 10 )Austenitic, Type 4 364 5 2.4 G NCELAustenitic, Type 4 402 2370 0.8 U INCO( 1 0)Austenitic, Type 4 402 2370 0.9 C NCELAustenitic, Type 4 403 6780 2.0 U INCO(0')Austenitic, Type 4 723 5 2.0 C NCELAustenitic, Type 4 763 5 2.0 C NCELAustenitic, Type D-2 366 5 2.4 INCO 10 )Austenitic, Type D-2 402 2370 1.1 U INCO( 1 0 )Austenitic, Type D-2 403 6780 1.2 U INCO( 10 )

Austenitic, D-2B 366 5 2.7 G INCO(0)-Austenitic, D-2B 402 2370 0.9 U INCO( 1 0 )Austenitic, D-2B 403 6780 1.6 U INCO( 1 0 )

Austenitic, D-2C 364 5 3.2 G NCELAustenitic, D-2C 402 2370 1.8 U NCELAustenitic, D-2C 723 5 3.1 U NCELAustenitic, D-2C 763 5 2.8 U NCEL

Austenicic, D-3 366 5 3.2 C INCO( 1 0 )Austenitic, D-3 402 2370 0.7 U INCO( 1 0)Austenitic, D-3 403 6780 z,7 G INCO(IO)

Austenitic, 366 5 2.6 U INCO(0)-Hardenable

Austenitic, 402 2370 1.8 U INCO( 1 0)Hardenable

Austenitic. 403 6780 1.1 UINCO(0)Hardenable

1. MPY - Mils penetration per year calculated from weight loss2. Symbols for types of corrosion:

CR - Crater type pitsET - Etched

G - GeneralNC - No visible corrosion

U - Uniform3. Numbers refer to references at end of paper

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t 6

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69

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6 2219-TSI0 3003-H140 083-14113* 5086-H34S6061.T6

2 _

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70 20 40 60 80 10o0 120 140

Maximum Pit Depth (mils)

Figure 5. Maximum depths of pits of aluminum alloys vs depth after 1 yearof exposure.

70

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Figure 9. Corrosion rates and maximum depths cf pits of aluminum alloys vs

time of exposure in surface seawater.

74

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* /• Copper alloys

Y; C) Nickel-silver #752

2 /____

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Oxygen (mill) or Corrosion Rate (mpy?

Figure 10. Corrosion of copper alloys vs depth after 1 year of exposure.

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'.e I_________ _____/___

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Figure 16. Corrosion of nickels and nickel-copper alloys vs oxygen contentof seawater after 1 year of exposure.

81

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(Cot 1_ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ __ __ _ _ _ _ _85

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86)

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7 A8

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0 10 200 300 00 00 60 70 So

2 ~ ~ ~ ~ ~ Tm __ - _ _ _ _ _ _ _

Fiur 221orso fsel stm fepsr ttesrae

87I

/-///Surf Sci _____________

2 2 • I 1/ eGrey C,

| 0 Alloy cast irons (Ni, Ni Cr s1 & 2, ductile =i & 2)i Austenitic Cl (types a1, 2, 3, 4, D-2,D0-28, D-3 and hardenable)- Si + Si Mo cast irons

• 0

IEI

7

0 1 2 3 4 5 6 7

Oxygen (mi/I) or Corrosion RaaU 'moy)

Figure 23. Corrosion of cast irons vs depth after 1 year of exposure.

88

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i

I

4)

0_____ _____ - 6- 4)

N'-I

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Oxygen ImI/I) or Corrosion Rate w'~py)

Figure 26. Corrosion of 200 and 400 Series stainless Steels vs depthafter 1 year of exposure.

91

0

I-4

0

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D AISI 304 and 304L0 AISl 304 (sensitized)

12 ASt 325

0.0

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7 ___________ ____________-__________

0 1 2 3 4 7

Oxygen (mi/I) or Corrosion Rate (mpy)

Figure 28. Corrosion of 300 Series stainless steels vs depth after1 year of exposure.

93

*11

0 AISI 301/ AISI 302. 316, 316 (sensitiaed), 330, 347": AISI 304 and 304L* AISI 304 (sensitized)

6/

5. /I

34

C.2

3I

0

/I

Oxygen (mi/I)

Figure 29. Corrosion of 300 Series stainless steels vs concentrationof oxygen in seawater after 1 year of exposure.

94

Sufc/,00 xyge

AII60H2

AIS 631TH0

0 _ _ _ _ _ _ 4_ _

Oxygn (I/0 r Crroson ate mDIFigue 3. Coroson f 60 Seies tailes stels s deth fte

I yer ofexpoure

____________________________ _______________ _______________5

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0 Load (anti monial, chemical end tellurium)

& Tin

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Figur 32. CorrsionOxygen (mill) or Corrosion Rate (mpV)I

Figue 3. Crroionof miscellaneous alloys vs depth after 1 yearof exposure.

97

6[(D Loa.d (atmna.chemical, tellurium)

& TinEI Zinc0 Lsed-tin volder

& MolybdenumS• ~Tungsten,

5-

(3-

0 1 2 3 4 5 6Oxygen (ml/I)

Figure 33. Corrosion of miscellaneous alloys vs concentration ofoxygen in seawater after I year of exposure.

98

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.,4.

U) 4

0

0 41

t.4 I~~)se oJ0

ii ___ ___99

REFERENCES

1. Naval Civil Engineering Laboratory. Technical Note N-781: Effectof deep ocean environment on the corrosion of selected alloys, byFred M. Reinhart. Port Hueneme, Ca., Oct 1965.

2. . Technical Report R-504: Corrosion of materials inhydrospace, by Fred M. Reinhart. Port Pueneme, Ca., Dec 1966.

3. . Technical Note N-900: Corrosion of materials inhydrospace - Part I - Irons, steels, cast irons and steel products, byFred M. Reinhart. Port Hueneme, Ca., Jul 1967.

4. _ Technical Note N-915: Corrosion of materials in hydro-space - Part II - Nickel and nickel alloys, by Fred M. Reinhart. PortHueneme, Ca., Aug 1967.

5. . Technical Note N-921: Corrosion of materials in hydro-space - Part III - Titanium and titanium alloys, by Fred M. Reinhart.Port Hueneme, Ca. Sep 1967.

6. . Technical Note N-961: Corrosion of materials in hydro-space - Part IV - Copper and copper alloys, by Fred M. Reinhart. PortHueneme, Ca., Apr 1968.

7. . Technical Note N-1008: Corrosion of Materials inhydrospace - Part V - Aluminum alloys, by Fred M. Reinhart. PortHueneme, Ca., Jan 1969.

8. . Technical Note N-1023: '.orrosion of materials in sur-face seawater after 6 months of exposure, by Fred M. Reinhart. PortHueneme, Ca., Mar 1969.

9. _ Technical Note N-1172: Corrosion of materials inhydrospace - Part VI - Stainless steels, by Fred M. Reinhart. PortHueneme, Ca., Jul 1971.

10. Dr. T. P. May. Unpublished data, International Nickel Co., Inc.,New York City, N. Y.

i00