WELDING AND OVERLAY PROCEDURES OF DISSIMILAR STEEL WELDING JOINTS IN THE NUCLEAR INDUSTRY

Angel Rafael Arce Chilque 1, Alexandre Queiroz Bracarense 1, Luciana Iglesias Lourenço Lima 1, Guilherme Marconi Silva 1, Marco Antônio Dutra Quinan 2, Mônica Maria de Abreu Mendonça Schvartzman 2,

Mariana Pessoa Medeiros 3, Gabriela Márcia Ribeiro 4

1Universidade Federal de Minas Gerais- Programa de Pós Graduação/Engenharia Mecânica, Belo

Horizonte, Minas Gerais – anarcec@yahoo.com, queiroz@demec.ufmg.br, lill@cdtn.br, gmarcsil@gmail.com.br

2Centro de Desenvolvimento da Tecnologia Nuclear, Serviço de Integridade Estrutural/Laboratório de Corrosão, Belo Horizonte, Minas Gerais, Brasil – monicas@cdtn.br, quinanm@cdtn.br

3Universidade Federal de Minas Gerais, Escola de Engenharia/Engenharia Metalúrgica, Belo Horizonte, Minas Gerais – anairamnininha@yahoo.com.br

4Universidade Federal de Minas Gerais, Escola de Engenharia/Engenharia Química, Belo Horizonte, Minas Gerais – gabi.gmr@hotmail.com

Abstract This work presents the GTAW welding of dissimilar ferritic steel type A508 class 3 and austenitic stainless steel type AISI 316 L using Inconel® 600 (A182 and A82) and overlay covering with Inconel® 690 (A52) as filler metal. Dissimilar welds with these materials without defects and weldability problems such as hot, cold, reheat cracking and Ductility Dip Crack were obtained. Comparables mechanical properties to those of the base metal were found and signalized the efficiency of the welding procedure and thermal treatment selected and used. This study evidences the importance of meeting compromised properties between heat affected zone of the ferritic steel and the others regions presents in the dissimilar joint, to elaborate the dissimilar metal welding procedure specification and weld overlay. Metallographic studies with optical microscopy and Vickers microhardness were carried out to justified and support the results, showing the efficiency of the technique of elaboration of dissimilar metal welding procedure and overlay. The results are comparables and coherent with the results found by others. Some alternatives of welding procedures are proposed to attain the efficacy. Further studies are proposed like as metallographic studies of the fine microstructure, making use, for example, of scanning electron microscope (SEM adapted with an EDS) to explain looking to increase the resistance to primary water stress corrosion (PWSCC) in nuclear equipments.

Key-words: Dissimilar weld metal, weld overlay, welding procedure, nickel based alloys 1. Introduction

Wrought Ni based alloy 600 and its correspondent weld metals, alloy A182 electrode and alloy A82 filler metal, are very used in pressurized water reactors (PWRs). It use is due to its inherent resistance to general corrosion, mechanical properties and impact test similar to the low alloy steel and stainless steel and its thermal expansion coefficient that is very close to that of low alloy and carbon steel. However in the last thirty years, stress corrosion cracking in PWR primary water stress corrosion cracking (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. The occurrence of

PWSCC has been responsible for significant downtime and replacement power costs. Repairs and replacements have generally utilized wrought Alloy 690 material and its compatible weld metals (Alloy 152 and Alloy 52), which have been shown to be very highly resistant to PWSCC in laboratory experiments and have been free from cracking in operating reactors over periods already up to nearly 15 years. It is nevertheless prudent for the PWR industry to attempt to quantify the longevity of these materials with respect to aging degradation by corrosion in order to provide a sound technical basis for the development of future inspection requirements for repaired or replaced component items [1]. The Brazilian nuclear power plants Angra 1 and Angra 2, make use of alloys 600 and its correspondent weld metals A182 and A82 as dissimilar welds in nozzles of the reactor pressure vessel and others parts. The locations in PWR where PWSCC may occur are shown in Fig.1.

PWSCC follows the three basics conditions of stress corrosion cracking (SCC) to occur: susceptible material, corrosive environment and the presence of tensile stress [2]. The microstructure of the welded joint plays an important role in stress corrosion cracking. The microstructures of susceptible metals can introduce hot, cold and reheat cracking, as well as interdendritic and grain boundaries containing precipitates, impurities, segregations and the typical solidification microstructures caused by welding that can further complicate the SCC behavior.

1.1. Preliminaires for Dissimilar Metals Welding From the point of view of welding, in order to elaborate a Dissimilar Metals Welding Procedure it is necessary to take into consideration different topics such as: identify the type of dissimilar metals to be welded, the filler metals, the design of the welded joint, the operational welding technique and heat treatment used, the welding inspection.

Fig. 1 - Locations in PWR where PWSCC may occur [1].

Ainsi in this case, the base metals to be welded are a low alloy steel SA508 class 3 with a high alloy steel ,austenitic stainless steel AISI 316 L; the filler metal, normally used is a nickel based alloy type inconel 600, A82 with GTAW for buttering and root passes and A182 electrode with SMAW for filling and finishing passes. For overlay, inconel 690 weld metal A52 will be used with GTAW. The chemical and mechanical properties of the base and filler metals will be controlled. The choice of the welded joint design, groove and penetration depend on the welding processes, thickness and quality of the weld required, ainsi as the accessibility, position of the welding and inspection technique.

The operational welding technique considers, otherwise, the cleanness of the welded joint and groove, the assembly, the pre-heat, inter-pass temperature and post-heat, the welding technique for deposition: in this work is used the “temper bead” technique (3). For buttering the ferritic steel and for weld overlay, low heat input is used to avoid the growing of the grain size and maintain a minimal of dilution. Definition of the welding parameters, (I, V, welding speed, heat input, etc), number of buttering layers, cleanness and preparation between passes, definition of welding deposition, sequence of beads and layers, the fill and finish pass, the external surface finish to receive the overlay, the post weld stress relief heat treatment, as well the welding inspection, (before, during and after welding), to be specified. Preliminary welds will be made in plates of the dissimilar metals in order to specify the procedure. 1.2. Weld Overlay Because of recent incidents related to primary water stress corrosion cracking (PWSCC) in pressurized water reactor (PWR) with nozzles welded with inconel 600 alloy and penetration locations welded with additional A82 and A182 metals, the use of overlays for mitigation and repair of various plants components has led to the use of corrosion resistant high nickel welding alloys (Ni-Cr-Fe) in particular alloy 52/52M which are known to be resistant to PWSCC. On the other side, many of the most susceptible locations have access limitations, which make examination difficult limiting the type of mitigation process that can effectively be applied. For this reason many of the utilities have decided to apply weld overlay to many of these alloys configurations. Full structural weld overlays subject the inner portion of the pipe to compressive stress, which is known to prevent the initiation of stress corrosion cracking. Several detrimental phenomena have been observed using this alloy in a wide range of applications including weld overlay for repairing of nozzle to safe – end locations on PWR`s. These weld discontinuities include micro-fissure, ductility dip cracking (DDC), lack of fusion (LOF), and lack–of–fusion (LOF). This has not been as significant as an issue with the manual filler rod 152, but is a concern due to the similar chemistries. In response to the welding problems developed the 52M product. The 52M alloy presents the advantage to give a weld with low values of aluminum oxides and low Niobium content and presents a better resistance to Ductility Dip Cracking ( DCP),but it is necessary to have more attention for other problems of weldability [4]. This work, explain about the welding and overlay covering of dissimilar ferritic steel type A508 class 3 and austenitic stainless steel type AISI 316 L using Inconel® 600 (A182 and A82) for the weld and Inconel® 690 (A52) for the overlay as filler metal, using specifics welding conditions. Some dissimilar welds with these materials are experienced as regard to the best welding procedures specifications capable to give dissimilar welded joint and overlay with good weldability, microstructures, mechanical properties and corrosion resistance. 2. Materials and Experimental Methods Table 1 shows the base metal and filler metals chemical compositions. Plates of alloys ASTM A-508 class 3 and AISI 316L were used to form the dissimilar metal welded joint. The plates were welded manually, following the welding procedures used for the nozzle to pipe welding in the Brazilian power plant Angra 1. The J groove weld was prepared by joining two 130 x 300 mm pieces of 36 mm (ASTM A-508 class 3) and 31 mm (AISI 316L) thick plate. It was produced by 3 root passes with gas tungsten arc welding (GTAW) with

82 alloy wire and 37 weld passes by shielded manual arc welding (SMAW) with 182 alloy electrode. A typical schema of the weld design is shown in Fig. 2, and the conditions for each weld pass are listed in Table 2. Before the welding, 5 layers of buttering were applied on the ASTM A-508 class 3 plate by manual gas tungsten arc welding with Alloy 82. The resulting thickness of the buttering was about 5 - 8 mm. Due to the carbon equivalent of the A508 steel (Ceq(iiw) = 0.604) after the buttering the piece was machined and post weld heat treated at 600ºC during 2 hours. The pieces were then pre-heated at 150 ºC before welding and the maximum inter-pass temperature was 200ºC in order to eliminated the hydrogen and avoid the cold cracking. After finished the dissimilar welded joint was not heat treated. The weldments were submitted to visual inspection, dye penetrant and radiographic tests, and no weld defects were revealed. After welding, the welded joint was cut in pieces for microstructural observation and mechanical tests.

Table 1 – Chemical composition of the base and fill er metals Meta

ls C Mn Si P S Cr Ni Nb Ti Cu Mo Al

316L 0.023

1.458

0.475

0.021

0.003

16.732

9.834 0.0199

0.029

0.142

2.097

0.011

SA 508

0.213

1.336

0.227

0.005

0.003

0.089

0.682 0.002

0.001

0.0559

0.505

0.011

182 0.047

5.810

0.572

0.015

0.006

14.930

71.820

1.890

0.183

0.019

- -

82 0.04 2.81 0.09 0.003

0.001

19.6 73.10 2.44 0.35 0.01 - -

52* 0.04 max

.

1.0 max

.

0.50 max

.

0.02 max

.

0.015

max.

28-31.5 max.

+Co-Re

mainder

Nb+Ta

0.10

1.0 max

.

0.30 max.

0.50 max

.

Al+Ti

1.5

• Special Metals Catalogue: (Fe-7.0-11.0; others: 0.50max); filler metal: diameter- 1.2mm.

Fig. 2 – The schematic weld design

Table 2 – Welding processes and conditions for vari ous weld passes

Vickers microhardness profiles across the weld metal and base metal interface were performed at a constant load of 100g and loading time of 25 seconds. For mechanical testing, specimens were taken from the weld plate and machined. The geometry of the tensile tests specimens is 4mm of diameter and they were prepared in accordance with standards ASTM G49 and ASTM E8. The samples were tested at room temperature and at 325ºC at a strain rate of 7x10-5mm/s. The mechanical properties are show in table 3.

Table 3. Mechanical Properties of Metals Type of Metals

Yield Strength YS0,2% (MPa)

Tensile Strength TS (MPa)

Elongation (%)

SA 508 345 550 – 725 18

316L 170 485 40

82 385 530 30

182 * 425 576 18

182** 359 591 48

52*** 552 30

* Room temperature; ** temperature 325°C ; *** Sp ecial Metals Catalogue

3. Results and Discussion Fig. 3 shows the cross section macrography of the finished welded joint. In the figure it is possible to observe the distinct regions of dissimilar metal welds. It is also possible to observe the dendritic structure of the weld zone. The blew lines indicate the places where microhardness Vickers HV100 were done.

10 - 15

10 - 15

Fig 3. Macrography of the dissimilar welded joint. Illustration of the different zones and indication of the microhardness lines measureme nts

Fig. 4 shows the microstructure of AISI 316 L base metal composed of polygonal austenitic grains with a small amount of delta ferrite. Figure 5 shows the microstructure of ASTM A508 class 3 base metal. The etching revealed a quenched and tempered structure.

Fig. 4 microstructure of the base metal

AISI 316L Fig. 5 microstructure of the base metal ASTM

A508 class 3. Fig. 6 (A) shows the interface between the A508 ferritic steel (black) and the Buttering (alloy 82). Fig. 6 (B) shows the buttering region, (C) the microstructure of the root area and (D) the weld pool region. The microstructures of alloys 182 and 82 weld metals are fully austenitic. The dendritic microstructure is clear in the buttering area and in the weld pool region. The grain structure is columnar and forms in the heat flow direction. The dendrites shapes depend on the position on the fusion zone. They are more closely spaced at the bottom part compared with the upper part of the weld.

Fig. 6 – Microstructure of dissimilar weld regions: (A) Interface A508(black)/A82(buttering);

(B) buttering (middle); (C) root area – alloy 82;(D ); pool weld (alloy 182). Fig. 7 shows the fusion line between alloy 182 and AISI 316L. The interface shows the presence of unmixed zone, the portion of the base metal that melted and solidified during

the welding process. Welds between dissimilar combinations are known to exhibit unmixed or partially mixed zones where the microstructure and chemical composition are quite different from that of the surrounding weld metal [3].

Fig. 7 – Microstructure of fusion line between alloy 182 and AISI 316L

It was observed some inclusions, ferrite, segregation and secondary phase precipitated in the weld metal grain boundary and in the dendrites grain boundaries. A detailed characterization of the chemical composition of the segregation and secondary phase precipitation is in elaboration that will be matter of another publication. The microhardness Hv measurements were taken along a line in the top, middle and bottom of the weld included both base metals, the heat affected zone (HAZ) and the weld area as showed before in Fig. 3. The distributions of microhardness are graphically presented in Fig. 8. In Fig. 8, the profile lines 1 and 3 show the distribution of the microhardness along the entire dissimilar welded joint. In particular the results showed that the hardness Hv in the HAZ of the ferritic steel is of the same order of the others parts of the welded joint. This meaning that the pos-weld heat treatment applied after buttering was appropriated to eliminate the quenched structure present in the HAZ of the ferritic steel. These profiles together with the 2 and 4 profiles of weld metal and buttering region respectively, showed microhardness values from 180 to 270 HV100. The continuous and relative smooth variation of the hardness in the welded joint is similar to the tensile strength showed in Table 3. The results obtained for the dissimilar welded joint with the welding procedure designed show that it is possible to meet a good compromise between microstructures, mechanical properties and appropriate weldability of different regions with capacity to guarantee the integrity of the welded joint. It is still necessary to do a specific microstructural and microchemical study of the sub-structures of the different regions to explain some differences in the fusion line, root and weld pool zone caused by the multipass technique used. This will help to explain the unlike behavior that may be met between these regions from the point of view of the corrosion and weldability [6].

(a)

(b)

Ha

rdn

ess

(H

v)

Distance ( mm)

Profile 1

Distance (mm)

Ha

rdn

ess

Hv

(c) (d) Fig. 8. Microhardness Hv distribution in the line 1 (a), line 2 (b), line 3 (c) and line 4 (d)

showed in Figure 3.

Fig. 9 shows the macrography for the dissimilar welded joint after deposit of four preliminaries layers (overlay) of inconel A52 with GTAW. No defects were detected in the visual inspection of the weld for any of the two welding conditions used and showed in Table 4. Fig. 10 shows, by one side the underbead Hardness Hv in the HAZ in the as welded conditions, with 90 and 130 Amperes(samples 1 and 3 respectively), giving values between 400 and 500 Hv, this results denotes the small influence in the hardness of the welding current choices in this work; by other side, the profile of Vickers micro hardness take under the beads in the HAZ, where the beads were deposited side by side such as to produce a layer, welded with preheat from 150 to 200°C(samples 5 and 7), high values of the hardness Vickers between 300 to 500 Hv are found, showing some small influence of the pre-heat used in the hardness.However an apparently cyclical variation of the hardness showed would be related to some small thermal effect of one bead on other one in the form as deposited, side by side. Fig. 11 shows the profile of the micro hardness Hv taked under the overlay (with four layers) in the HAZ of the ferritic steel welded using the temper weld technique without grinding with pre-heat and interpass temperature between 150-200°C (condition 1). The beads in all the layer s were deposited such as one bead was deposited above 50% of the other one trying to obtain a heat treatment of one bead up the other.Values of HV100 between 260 to 380 are presents in the growing grain size region of the HAZ of the ferritic steel using the condition 1 as welding. Fig.12 show the profile of the Vickers hardness taked under the layers in the HAZ of the ferritic steel welded with pre-heat and interpass temperature ranging from 200 to 250° C (condition 2); values of HV 100 of the same order of the condition 1 are obtained in the growing grain size region of the HAZ.

Fig. 9. Macrography of dissimilar welded joint over lay with four layers of inconel A52

Table 4. Welding overlay parameters

Overlay with preheat and

Process Filler Electrode size

Current Voltage Travel speed

Ha

rdn

ess

(H

v)

Distance (mm)

Ha

rdn

ess

(H

v)

H

ard

ne

ss (H

v)

Distance (mm)

Interpass Temperature

(°C)

Metal (mm) (A) (V) (mm/s)

Condition 1: 150 to 200

GTAW 52 1.2 90 – 130

10 – 15 1.8 – 3.0

Condition 2: 200 to 250

GTAW 52 1.2 90 – 130

10 – 15 1 – 1.5

Amostra 93 A - Perfil LF

0

50

100

150

200

250

300

350

400

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6 6,5 7 7,5

Distância (mm)

Mic

rodu

reza

(H

V)

Fig. 10 - Underbead Hv 100 in the HAZ of the SA 508 –

Welded without pre-heat (1,3); with pre-heat (5,7).

Fig. 11- Profile of Hv 100 in the HAZof the SA 508 steel – welded with pre-heat at 150 to

200°C and temper bead (condition 1)

Fig 12. Underlayer Hv 100 in the HAZ of the 508 – with pre-heat and interpass at 200 to

250°C and temper bead (Condition 2)

Fig.13. Underlayer Hv 100, in the HAZ of the AISI 316L steel.(condition 1)

Fig.14 shows a distribution of Vickers hardness from the overlay to the HAZ of the ferritic steel welded with pre-heat and interpass temperature ranging from 200 to 250°C (condition 2) and temper bead technique. There is a variation of hardness between 230 to 320 from the fusion line of the overlay to the HAZ of the ferritic steel. The results of the figures 11,12 and 14 for the HAZ of the ferritic steel, show that the temper bead technique as applied in this work with the welding procedure specified for overlay is the main factor responsible for lower the hardness in the grain size region of the HAZ; others factors such as current intensity and pre-heat and interpass temperature have a complementary influence, in the limits of the conditions retained in this work. In fact, the temper bead technique is performance such as annealed or tempered heat treatment on the HAZ of the

Mic

ro H

ardn

ess

(HV

) H

v

Distance (mm) Distance (mm)

Sample 1 Sample 3 Sample 5 Sample 7

Ha

rdn

ess

Hv

Sample 4 Sample 2

Mic

ro H

ardn

ess

Hv

Distance (mm)

Mic

ro H

ardn

ess

Hv

Distance (mm)

As welded with 90 A

As welded with 130 A

One layer with 4 beads -90A

One layer with 4 beads – 130A

Profile Hv, sample 93

Profiles Hv, samples with only one layer

Sample 23

ferritic steel in this case, changing and giving appropriates microstructures to the great part of the HAZ; in particular the HAZ of the ferritic steel shows in general a quenched and tempered microstructure.The Overlay welding procedures using pre - heat and interpass temperature between 150 to 200°C and 200 to 250°C t ogether to the temper bead technique allows in general the attenuation of the hardness in the HAZ of the ferritic steel with values HV100<350. Values of HV100>350 are indicatives of others weldability problems such as cold cracking, embrittlement and under cladding cracking in the structure [5]. The variation of microhardness inside each zone, is related too with the fine microstructure, second phase and precipitates presents and it is matter of other study in course using, in particular, scanning electron microscope (SEM), (EDS) and microprobe analysis [9].

Fig. 13 showed the microhardness of the HAZ of the AISI 316L of the same magnitude, HV100= 200. Fig. 15 shows the microstructure of the weld overlay (A52) deposited on the AISI 316 L. As can be observed, a fine dendritic substructure is related to the hardness Hv variation 220 to 250 HV100. In the experiences made, no defects, such as the Ductility Dip Cracking (DDC) detected by others authors (7 – 8) were found.

Perfil vertical da Amostra 25

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7 8 9

Distância (mm)

Dur

eza

(HV

)

Final da solda

Fig. 14. Microhardness Vickers Hv distribution from the overlay to the HAZ of the 508 steel with 200°C to 250°C of pre-heat and interpass tempe rature and temper bead technique

(condition 2).

Fig. 15. Microstructure of the layers with Inconel A52 on the HAZ of the AISI 316L

As showed before, the different regions of the dissimilar welded joint and overlay, had similar properties with the welding procedures used in this work. Others authors recommend to use the filler metal A52 with T< 350°F (<178°C) as pre-heat and interpass

Distance

Fusion line

V

icke

rs H

v

508

Overlay inconel A52

temperature because of the oxidation at high temperature of some elements, like Al presented in the weld metal of A52 (4 ). This study is coherente with this recommendation. By the way, it is necessary to meet a compromise in order to obtain a satisfactory solution to the potential weldability problems to the dissimilar welded joint and overlay, avoiding the martensite microstructure, obtaining satisfactory microhardness in the HAZ of the ferritic steel and a satisfactory solution to the eventual weldability problems in the fusion zone such as the oxidation of the layers in the overlay by other part. The layers used in this study don’t make use of the grinding between each layer such as used in the temper technique by others authors (1); perhaps in order to compare would be interesting to considere the grinding of the beads just to remove 50% before to deposit the next layer, of course this solution will be more expensive. The welding procedure is in advanced in order to finish the qualification of the weld overlay procedure in plates, with some experiences being realized with the temper bead technique at ambient temperature. After, to simulate the welding in real conditions of components in the reactor making use of a Mock up prepared for it. Follow the measure of the residual stresses in the inner part of the mock up will be done looking for mitigation of the primary water stress corrosion cracking (PWSCC) problem, through the introduction of compressive residual stresses in the inner part of the dissimilar welded joint. 4. Conclusion The study update performed on the elaboration of the Dissimilar Metal Welding Procedure and Weld Overlay for the junction of ferritic ASTM 508 class 3 with AISI 316 L stainless steel with Inconel A82 and A182 for welding and Inconel A52 for overlay covering, allow to reach the following conclusions: 1. The methodology utilized to elaborate the dissimilar metal welding procedure specification and weld overlay of dissimilar metal welded joint, showed appropriated for qualification and practical application. The results are coherent with the best practice utilized by others authors. 2. The Dissimilar Welding Procedure elaborated for joining the dissimilar metals, allows obtaining a good compromise between the microstructures and mechanical properties of the different zones and regions of the welded joint showing good weldability. 3. For the overlay, it was possible to elaborate a dissimilar metal welding procedure specification trough the consideration of a compromise taken in account the structural integrity of the welded joint, using pre-heat and interpass temperature at 150°C to 250°C together to the temper bead technique without grinding, avoiding in particular the quenched structures in the ferritic HAZ. The temper bead technique showed to be the main factor for to allow an apropriate microstructure and mechanical properties in the growing grain size region of the HAZ. This way was possible to obtain a good weldability of the different regions in the overlay joint. 4. The classical techniques optical metallography, microhardness and tensile test has been appropriates to check the weldability and to elaborate a dissimilar metal welding procedure and overlay for the dissimilar joint used in the nuclear industry

5. Further study will be necessary to be performed to explain some of the results. Among these studies the analysis of the fine microstructure using, for example, the Scanning

Electron Microscope (SEM) with EDS and microprobe analysis. Another study will be the weldability of the dissimilar weld overlay with the temper bead technique at ambient temperature. Other study would be concern the resistance to impact and fracture mechanics, tests in the weld and in the dissimilar welded joint. Other study should be the study of the dissimilar metal welding and weld overlay with differents welding processes and filler metals.

Acknowledgements The authors would acknowledge FINEP and Eletronuclear for the funding to develop the research and Cnpq for sponsoring the support to the students. To the students, Gabriela Marcia Ribeiro and Mariana Pessoa. References [1]. J. HICKLING, C. KING, . Materials Reliability Program: Resistance to Primary Water Stress Corrosion Cracking of Alloys 690, 52, 152 in Pressure Water Reactor – Technical Update, March 2004. [2]. GEORGIA POWER COMPANY, ELECTRIC POWER RESEARCH INSTITUTE, Inconel Weld Overlay Repair for Low – Alloy Steel Nozzle to Safe – End Joint. Final Repport, January 1991. [3]. Warren F. Savage, Solidification, Segregation and Weld Imperfections, 1980 Houdremont Lecture – IIW Welding in the World, 89 – 114, Vol. 18, N° 5/6, 1980. [4]. C. LATIOLAIS, G. FREDERICK, Overlay Handbook, EPRI, 2007 [5]. DHOOGE, R.E. DOLBY, J. SEBILLE, R. STEINMETZ, A.G. VINCKIER, A Revue of Work Related to Reheat Cracking in Nuclear Reactor Pressure Vessel Steels, doc. IIW com IX – 1137-79, IIW. [6]. SINDO KOU, Welding Metallurgy, Second Edition, 2003. [7]. M.G. COLLINS AND J.C. LIPPOLD, An investigation of Ductility Dip Cracking in Nickel – Based Filler Materials – Part I, Welding Journal, 288-S – 295-S, vol , October 2003. [8]. F.F. NOECKER II and J.N. DuPONT, Metallurgical Investigation into Ductility Dip Cracking in Nickel – Based Alloys: Part II, Welding Journal, 62-s – 77s, Vol. 88,March 2009. [9]. LUCIANA IGLÉSIAS LOURENÇO LIMA, GUILHERME MARCONI SILVA, ANGEL RAFAEL ARCE CHILQUE, MÔNICA MARIA DE ABREU MENDONÇA SCHVARTZMAN, ALEXANDRE QUEIROZ BRACARENSE, MARCO ANTÔNIO DUTRA QUINAN, Characterization of Alloy 82/182 Dissimilar Metal Weld Between Low Alloy Steel ASTM A-508 and 316L Stainless Steel. (to be published).