Critical Condition for Hydrogen Induced Cold Cracking of High Strength Weld Metal

2014 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Hitoshi Sueyoshi ◽  
Shigeru Endo
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Weld Metal ◽  
Hydrogen Concentration ◽  
Hydrogen Content ◽  
Weld Joint ◽  
High Strength ◽  
Cold Cracking ◽  
Critical Conditions ◽  
Delayed Fracture

The critical conditions of hydrogen content and residual stress in the high strength steel weld with the tensile strength level of over 980MPa were investigated. The critical hydrogen concentration for the cold cracking in the Y-grooved constraint weld joint was evaluated with intentionally introducing hydrogen gas. Residual stress conditions at the “root” portion in the weld joint were evaluated by the neutron diffraction technique. It was found that the root portion showed highest tensile stress of over 1110MPa in the transverse direction, and cracking occurred when the average hydrogen content was over 2ppm. In order to clarify the critical conditions of the principal tensile stress and local accumulated hydrogen concentration of the weld metal, the delayed fracture testing by using the notched round bar specimen with electrochemically hydrogen charged was conducted. It was seen that the cold cracking behavior in the Y-grooved weld joint was explained by the critical conditions of the maximum principal stress and the local accumulated hydrogen content obtained from the delayed fracture with the small specimen.

scholarly journals Failure Analysis of Weld Metal Cracking in Weld Joint of API 5L X 75 Pipelines Steel

2018 ◽  
Vol 7 (4.7) ◽  
pp. 401
Author(s):  
Abbas Kamil ALrubaeiy ◽  
. . ◽  
. .
Keyword(s):  
Weld Metal ◽  
Failure Analysis ◽  
Weld Joint ◽  
Pipe Steel ◽  
High Strength ◽  
Cold Cracking ◽  
Steel Alloy ◽  
Preheat Temperature ◽  
Thin Walled

The development of steel alloy which result thin walled, high strength API 5L X75 grade, a restricting parameter controlling widespread use of X75 is the susceptibility to weld metal tracks. The excellent weld ability of this grade of the pipe steel has enhanced the potential for the use of high strength cellulose consumable like E6010 in root pass welding, but the risk of hydrogen assisted cold cracking (HACC) is also increased because of the high strength weld metal. This investigation outlines , the use of grade (E6010) of commercial cellulose consumable to assess conditions leading to hydrogen assisted cold cracking in the diluted weld metal. The research contained clarification of the link among microstructure; preheat temperature and hardness amounts for the weld consumable and its effect on cracking susceptibility. The cracking morphology studies indicated that there are many ways in which the crack can propagate in the weld metal and HAZ region. The mode of cracking observed was microvoide coalescence.    

Effect of Weld Metal Microstructure on Cold Crack Susceptibility of High Strength Weld

2008 ◽  
Vol 580-582 ◽  
pp. 13-16
Author(s):  
Hee Jin Kim ◽  
Jun Seok Seo ◽  
Jae Hak Kim ◽  
Ka Hee Kim ◽  
Jin Hyun Koh ◽  
...  
Keyword(s):  
Weld Metal ◽  
Hydrogen Content ◽  
High Strength ◽  
Cold Cracking ◽  
Diffusible Hydrogen ◽  
Fca Welding ◽  
Flux Cored Arc Welding ◽  
Metal Microstructure ◽  
Multipass Weld ◽  
Crack Susceptibility

Facing the practical difficulties in reducing the diffusible hydrogen content of fluxcontaining welding consumables like flux-cored arc welding (FCAW) wires, the present study investigated the microstructural aspect to improve the hydrogen-induced cold crack (HICC) resistance of multipass weld metal of 600MPa strength. Two FCA welding wires were prepared by controlling the Ni content to give different weld microstructure, but to have similar levels of hardness and diffusible hydrogen content. HICC susceptibility of those two consumables was evaluated by 'G-BOP test' and also by 'multi-pass weld metal cold cracking test'. As a result of this study, it was demonstrated that microstructural modification with decreased proportion of grain boundary ferrite (GF) improved cold crack resistance of weld metal. The detrimental effect of GF against HICC has also been addressed based on the characteristics of weld metal cold cracking.

scholarly journals Cold Crack Susceptibility studies on High Strength Low Alloy Steel 950A using Tekken Test

2017 ◽  
Vol 13 ◽  
pp. 25-31
Author(s):  
Manivelmuralidaran Velumani ◽  
M. Sakthivel ◽  
M. Balaji
Keyword(s):  
Weld Metal ◽  
Alloy Steel ◽  
Acicular Ferrite ◽  
Test Procedure ◽  
High Strength ◽  
Cold Cracking ◽  
Low Alloy Steel ◽  
Cracking Resistance ◽  
Preheating Temperature ◽  
Crack Susceptibility

In This research article deals with the study of cold cracking susceptibility of High Strength Low Alloy Steel (HSLA) 950A using Gas Metal Arc Welding process (GMAW). The cold cracking is a general problem while welding HSLA steels. It thus becomes mandatory to have a novel method of welding to minimize the effects of cold cracking. The cold cracking tendency of the material is determined using the Y groove Tekken test and the test is carried out with DIN EN ISO 17642–2 standard. The welding of the base metal has been carried out using the low hydrogen electrode ER 70SD2. The test procedure is followed under self-restraint condition for determining cold cracking susceptibility of weld metal. Micro structural constituent of the weld metal plays an important role in determining the cold crack susceptibility of the weld metal. Hence an attempt has been made to impart the microstructure having high resistance to cold cracking.  It has been observed that Acicular ferrite microstructure in the weld metal increases the cold cracking resistance of the welded joint.  In the present study, the effect of preheating temperature on cold crack susceptibility analyzed by varying the preheating temperature 100ºC, 150ºC and acicular ferrite microstructure observed in the microstructure analysis of the welded specimen. The effect of microstructure on cold cracking has also been established. But due to very limited range of temperature, the effect of preheating temperature on cold crack susceptibility was inconclusive. But the formation of acicular ferrite microstructure will have greater influence on cold crack susceptibility. In future, effects of Nickel, Manganese and other alloying elements of the filler material in increasing cold cracking resistance can also be studied for far reaching prospects of the research.

Critical Conditions of Cold Cracking in High Strength Steel Weld Based on the Local Stress Distribution and Hydrogen Accumulation

2018 ◽  
Vol 941 ◽  
pp. 153-157
Author(s):  
Yuya Sato ◽  
Yoshiaki Murakami ◽  
Igi Satoshi ◽  
Nobuyuki Ishikawa
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Hydrogen Diffusion ◽  
Local Stress ◽  
High Strength ◽  
Initiation Site ◽  
Cold Cracking ◽  
Diffusion Behavior ◽  
Root Region ◽  
Hydrogen Accumulation

In this study, the occurrence of cold cracking in high strength steel welds were investigated in terms of residual stress and hydrogen diffusion behavior. The y-groove weld cracking test of TS780MPa grade steel plate was conducted with intentionally introducing hydrogen into the shielding gas during the gas-metal arc welding (GMAW). Since local stress is one of the most important factors for the cold cracking, residual stress distribution in the weld joint was measured by the neutron diffraction using TAKUMI in J-PARC. The root region, which is usually the crack initiation site in the y-groove cold cracking test, was under a multi-axial stress state and showed highest tensile residual stress in the transverse direction. It was considered that hydrogen diffusion and accumulation could be enhanced in the high stressed root region, resulting in cold cracking. Therefore, hydrogen diffusion behavior and stress distribution in the y-groove weld joint was investigated by a coupled thermo elastic plastic and hydrogen diffusion analyses. Hydrogen accumulation occurred in the root region where showed highest hydrostatic stress. The point where showed the hydrogen accumulation was well corresponded to the crack initiation site. It was indicated that local hydrogen concentration after welding was another important key factor for the cold cracking. From these investigations, it was essential to take the combination of local hydrogen concentration and residual stress distribution near the root region into account for the highly precise estimation of cold cracking.

Application of Local Approach to Hydrogen Embrittlement Fracture Evaluation of High Strength Steels

2007 ◽  
Vol 539-543 ◽  
pp. 2155-2161 ◽  
Author(s):  
Shusaku Takagi ◽  
Satoshi Terasaki ◽  
Kaneaki Tsuzaki ◽  
Tadanobu Inoue ◽  
Fumiyoshi Minami
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Content ◽  
Fracture Property ◽  
Martensitic Steel ◽  
High Strength Steels ◽  
High Strength ◽  
New Method ◽  
Local Approach ◽  
Delayed Fracture ◽  
Ultra High Strength Steel

A new method for evaluating the hydrogen embrittlement (HE) susceptibility of ultra high strength steel was studied in order to propose a new method for assessing the delayed fracture property. The material used was 1400MPa tempered martensitic steel with the chemical composition 0.40C-0.24Si-0.81Mn-1.03Cr-0.16Mo(mass%). The local approach originally used for evaluating the brittle fracture property was applied to HE susceptibility assessment after modifying the method to include the effect of hydrogen content. Critical HE data used in the modified local approach was obtained by a stepwise test in which alternating processes of stress increase and stress holding were repeated until the specimen fractured. The specimen used in the stepwise test was 10 mm in diameter and the stress concentration factor was 4.9. Assessment of HE susceptibility for specimens with other dimensions entailed the use of a critical hydrogen content for failure, Hc, representing the maximum hydrogen content among the unfractured specimens in the HE test with constant loading. Matters to be noted for obtaining the material parameters are discussed.

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