C: max. 0,070 Cr: 15,0 – 17,0 Ni: 3,0 – 5,0 Cu: 3,0 – 5,0 Nb: max. 0,45

1.4542 X5CrNiCuNb 16-4

1.4542 Precipitation hardening stainless steel Relevant current and obsolete standards: �� EN 10088-3 : 1.4542 X5CrNiCuNb 16-4 �� AISI : - �� ASTM : A 564-89 17-4 PH : Type 630 General properties �� corrosion resistance : good �� mechanical properties : excellent �� forgeability : good �� weldability : good �� machinability : poor Physical properties �� density (kg/dm3) : 7,8 �� electrical resistivity at 20°C (� mm2/m) : 0,71 �� magnetisable : yes �� thermal conductivity at 20°C (W/m K) : 16 �� specific heat capacity at 20°C (J/kg K) : 500 �� thermal expansion (10-6K-1) between 20 and 100°C : 10,9 20 and 300°C : 11,1 Typical applications �� marine applications �� pulp and paper industry �� pump component �� mechanical engineering �� sport and leisure (golf clubs) �� aerospace and aviation Processing �� automated machining : not common �� machinable : yes �� hammer and die forging : yes �� cold forming : no �� cold heading : no �� suited to polishing : yes

Finished product forms and conditions �� wire rod, Ø 5,5 - 27 �� peeled bars � 20 - 120 �� bright bar h9, � 6 - 78 �� bright coils h9, Ø 5 - 20 �� solution annealed �� tempered �� drawn �� straightened �� ground Demand tendency � Corrosion resistance (PRE = 15,0 to 18.98) The good combination of corrosion resistance and excellent mechanical properties make this grade of steel suitable for use in many marine environments where the corrosion resistance and mechanical properties of the martensitic grades of stainless steels are not sufficient. Although used in marine applications, 1.4542 is suscepti-ble to crevice corrosion in stagnant sea water. In fact when used in any application where continu-ous operation is not possible, additional protec-tion is recommend. When exposed to coastal atmospheres, a gradual discoloration will occur followed by pitting. In general it can be assumed that the corrosion resistance of 1.4542 is very similar to 1.4301. The exception to the above is that 1.4542 is sig-nificantly more resistant to stress corrosion cracking. Heat treatment / mechanical properties 1.4542 may be solution annealed by holding in the temperature range 1020 to 1050°C followed by rapid cooling in water, oil or air, depending on the cross-section of the component. It is impor-tant to ensure that the component is allowed to cool to room temperature, to ensure that austen-ite transforms to martensite, prior to further heat treatment is performed. In the solution annealed condition, the following mechanical properties may be attained when testing in the longitudinal direction: Property Specification - tensile strength (N/mm2) Rm : �1200 - hardness HB : � 360

Revision No. 4542-0 Created: 22.06.2000

Properties, applications and processing

The mechanical properties of 1.4542 are depend-ent on the heat treatment that has been performed, i.e. the amount of precipitation that has occurred. The following precipitation hardening treatments are usually specified:

Condi-

tion

Common heat

treatment

Precipitation

hardening

Minimum tensile

strength, N/mm2

P 800 2h 760°C/air + 4h 620°C/air

800

P 930 4h 620°C/air 930 P 960 4h 590°C/air 960 P 1070

Solution an-

nealing 1030 - 1050°C/oil,

water. 4h 550°C/air 1070

The number after the ‘P’ refers to the minimum tensile strength in N/mm2:

In these heat treated conditions, the following me-chanical properties can be expected: Property Spec. P800 Spec. P930 - yield strength (N/mm2) Rp0,2 : � 520 � 720 - tensile strength (N/mm2) Rm : 800 - 950 930 - 1100 - tensile elongation (%) A5 : � 18 � 16 - impact energy (J) @ 25°C ISO-V : � 75 � 40 Property Spec. P960 Spec. 1070 - yield strength (N/mm2) Rp0,2 : � 790 � 1000 - tensile strength (N/mm2) Rm : 960 - 1160 1070 - 1270 - tensile elongation (%) A5 : � 12 � 10 Common ASTM specifications:

Condi-

tion

Common heat

treatment

Precipitation

hardening

Minimum tensile

strength, N/mm2

H1150M 2h 760°C/air + 4h 620°C/air

795

H1150 4h 620°C/air 930 H1100 4h 595°C/air 965 H1075 4h 580°C/air 1000 H1025

Solution an-

nealing 1030 - 1050°C/oil,

water.

4h 550°C/air 1070 In this case the number following the ’H’ designates the precipitation hardening heat treatment temperature in Fahrenheit. In these heat treated conditions, the following me-chanical properties can be expected: Property Spec. H1025 Spec. H1075 - yield strength (N/mm2) Rp0,2 : � 1000 � 860 - tensile strength (N/mm2) Rm : �1070 � 1000 - tensile elongation (%) A5 : � 12 � 13 - impact energy (J) @ 25°C ISO-V : � 20 � 27 Property Spec. H1100 Spec. H1150 - yield strength (N/mm2) Rp0,2 : � 795 � 725 - tensile strength (N/mm2) Rm : � 965 � 930 - tensile elongation (%) A5 : � 14 � 16 - impact energy (J) @ 25°C ISO-V : � 34 � 41

Welding Prior to welding 1.4542, consideration must be given to the condition of the base material. The copper within the steel is present in a stable form and will not promote hot cracking. Post weld heat treatment is required to ensure that the required mechanical properties are obtained, both for the weld region and the parent metal. Apart from ensuring good welding practice, care must be taken to avoid under cutting or any other welding defect which could result in the formation of a notch. Elevated temperature properties The following minimum tensile properties at various temperatures are specified in the EN 10088-3 : 1995 standard. 900

/m

m2 )

ess

(N

str

roof

mum

p

Min

i

Forging

400

450

500

550

600

650

700

750

800

850

50 100

150

200

250

300

350

Test temperature ( C)

P930

P800

P960

P1070

Forging of 1.4542 usually takes place in the tem-perature range 1100 to 800°C followed by air cool-ing to room temperature to ensure grain refine-ment. Heat treatment after forging is required to obtain the required properties. Machining 1.542 is machinable in both the solution annealed and hardened conditions. The machinability of this grade of stainless steel is directly related to its hardness. Although it must be realised that the machining parameters will vary depending on the struc-ture/hardness of the steel, the following parameters can be used as a guideline when machining with coated hardmetal tools: tensile strengths depth of cut (mm)

feed (mm/rev) Rm in N/mm2 6 mm

0,5 mm/r 3 mm

0,4 mm/r 1 mm

0,2 mm/r annealed 900 - 1100

m/min 100

m/min 160

m/min 190

Revision No. 4542-0 Created: 22.06.2000