Prevention of cold cracking by the welding process for reducing diffusible hydrogen in high-tensile thick plate welding

2019 ◽  
Vol 33 (7-9) ◽  
pp. 268-279
Author(s):  
Naoki Mukai ◽  
Yoshihide Inoue ◽  
Shuji Sasakura ◽  
Yuta Kinoshita
Keyword(s):  
Thick Plate ◽  
Welding Process ◽  
Cold Cracking ◽  
Diffusible Hydrogen

Repair Weldability at Overlay/Base Metal Interface of Petroleum Pressure Vessel

2008 ◽  
Author(s):  
Rinzo Kayano ◽  
Hiroaki Mori ◽  
Kazutoshi Nishimoto
Keyword(s):  
High Temperature ◽  
Hydrogen Embrittlement ◽  
Hydrogen Content ◽  
Welding Process ◽  
Pressure Vessels ◽  
Cold Cracking ◽  
Diffusible Hydrogen ◽  
Repair Welding ◽  
Crack Susceptibility

In order to extend the life of petroleum pressure vessels operated in long term, it is needed to establish the reliable repair welding technique. Weld cold cracking sometimes occurred in long-term operated petroleum pressure vessels due to hydrogen embrittlement by thermal stress and diffusible hydrogen after repair welding. The cracking was caused by the hydrogen concentration at the base meal of 2.25Cr-1Mo steel/overlaying metal of austenitic stainless steels interface during the service with high temperature and hydrogen partial pressure. The tendency was accelerated by carbide precipitation at the interface due to the post weld heat treatment (PWHT) and the operation with high temperature. That is, the crack susceptibility at the interface became markedly higher owing to the hydrogen embrittlement with metallurgical degradation by thermal embrittlement. To make clear the effect of weld thermal cycles during repair welding on the hydrogen content and weld cold cracking at the interface in the structural material of petroleum pressure vessels, the crack susceptibility was estimated by y-groove weld cracking test with varying overlay thickness and hydrogen exposure conditions. In addition, the hydrogen distribution in the material was calculated by the theoretical analysis using the diffusion equation based on activity. The crack susceptibility was raised with increase in the hydrogen content at the interface. It was concluded that the cracking could be prevented by controlling the repair welding process to reduce the hydrogen content at the interface.

scholarly journals The Effect of Cold Cracking Prevention of FCAW by the Welding Process for Reducing Diffusible Hydrogen

2019 ◽  
Vol 9 (1) ◽  
pp. 33-37
Author(s):  
Naoki MUKAI ◽  
Yoshihide INOUE ◽  
Shinichi TASHIRO ◽  
Tetsuo SUGA ◽  
Manabu TANAKA
Keyword(s):  
Welding Process ◽  
Cold Cracking ◽  
Diffusible Hydrogen

Cooling Rate Control on Cold Cracking in Welded Thick HSLA Steel Plate

2011 ◽  
Vol 689 ◽  
pp. 269-275 ◽  
Author(s):  
Winarto ◽  
Muhammad Anis ◽  
Taufiqullah
Keyword(s):  
Low Temperature ◽  
Cooling Rate ◽  
Thick Plate ◽  
Steel Plate ◽  
Hsla Steel ◽  
Welding Process ◽  
Cooling Time ◽  
Cold Cracking ◽  
Electric Heater ◽  
Cooling Media

Cold cracking phenomenon is a very significant problem on welding of steel. This phenomenon usually occurs after welding process finishes in more than 24 hours. Crack often takes place in the heat affected zone area. Generally, cold cracking is due to hydrogen diffusion during welding process, residual stress and susceptible microstructure at low temperature (below 150°C). Welding process on thick plate high strength low alloy (HSLA) steel gives a high risk to cold cracking phenomenon. The cooling rate of thick plate during welding may increase the absorbtion of heat compared to thin plate. Controlling cooling rate is the main factor on welding of thick HSLA steel plate. A single v-butt joint on HSLA and S45C by using Gas Metal Arc Welding (GMAW) has been investigated. This investigation was carried out on a 40 mm thick HSLA steel by controlling cooling rate and by using cooling media such as air, blanket and electric heater. The result shows that prevention of cold cracking can be made by controlling cooling time at low temperature (T300- T100) in order to keep the cooling time larger than the critical cooling time. The use of cooling media with electric heater can prevent the cold cracking at HSLA weldment. Crack can be found on the weldment due to the presence of stress concentration, local variation of hardness and microstructure, which may result in brittle fracture of the crack surface.

scholarly journals Cold Cracking Of Underwater Wet Welded S355G10+N High Strength Steel

2015 ◽  
Vol 15 (3) ◽  
pp. 48-56 ◽  
Author(s):  
D. Fydrych ◽  
J. Łabanowski ◽  
J. Tomków ◽  
G. Rogalski
Keyword(s):  
High Strength Steel ◽  
Welding Process ◽  
High Strength ◽  
Cold Cracking ◽  
Test Results ◽  
Ocean Engineering ◽  
Diffusible Hydrogen ◽  
Underwater Welding ◽  
Weld Area ◽  
Steel Joints

Abstract Water as the welding environment determines some essential problems influencing steel weldability. Underwater welding of high strength steel joints causes increase susceptibility to cold cracking, which is an effect of much faster heat transfer from the weld area and presence of diffusible hydrogen causing increased metal fragility. The paper evaluates the susceptibility to cold cracking of the high strength S355G10+N steel used, among others, for ocean engineering and hydrotechnical structures, which require underwater welding. It has been found from the CTS test results that the investigated steel is susceptible to cold cracking in the wet welding process.

Recent Development of HFW Linepipe With a High-Quality Weld Seam Suitable for Sour Service Environments

2014 ◽  
Author(s):  
Shunsuke Toyoda ◽  
Sota Goto ◽  
Yasushi Kato ◽  
Satoru Yabumoto ◽  
Akio Sato
Keyword(s):  
Crack Propagation ◽  
Chemical Reactions ◽  
Weld Seam ◽  
Welding Process ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Oxide Content ◽  
Electric Resistance ◽  
Diffusible Hydrogen ◽  
High Quality

Based on the appreciable progress being made in quality control and assurance technology for the electric resistance welding process, the number of applications for high-frequency electric resistance welded (HFW) linepipe in highly demanding, severe environments, such as offshore and sour environments, has gradually increased. Resistance to hydrogen-induced cracking (HIC) is the most important property for a linepipe to possess for use in sour environments. However, resistance to HIC, especially along the longitudinal weld seam, has not yet been fully related to metallurgical factors. In this study, to clarify the effects of inclusions on the sour resistance properties of X60- to X70-grade steels, their resistances to HIC were numerically simulated. For the simulation, the steels were assumed to have a yield strength of 562 MPa and a tensile strength of 644 MPa. To estimate the effect of nonmetallic inclusions, a virtual inclusion was situated at the center of a 10-mm-thick HIC test specimen. Tests were performed using NACE test solution A. The crack propagation rate was calculated as a function of the content of diffusible hydrogen, the diameter of the inclusion, and the fracture toughness of the matrix after hydrogen absorption. In the propagation calculation, the resistance to chemical reactions at the interface of the inclusion matrix was also considered to be a delaying factor. By assuming a resistance to chemical reactions at the interface, the crack propagation rate could be fitted to the actual HIC propagation rate. Based on the numerical simulation results, HFW linepipe with a high-quality weld seam was developed. Controlling the morphologies and distributions of oxides generated during the welding process is the key factor for improving the resistance to HIC. Using a combination of optimized chemical composition, microstructure and oxide content, the weld seam of the developed X70-grade HFW steel pipe showed excellent resistance to HIC.

Application of FIB/SEM/EBSD for Evaluation of Residual Strains and Their Relationship to Weld Metal Hydrogen Assisted Cold Cracking

2012 ◽  
Author(s):  
W. L. Costin ◽  
I. H. Brown ◽  
L. Green ◽  
R. Ghomashchi
Keyword(s):  
Residual Stresses ◽  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Ion Beam ◽  
Base Material ◽  
Welding Process ◽  
Cold Cracking ◽  
Predictive Methods ◽  
Residual Strains

Hydrogen assisted cold cracking (HACC) is a welding defect which may occur in the heat affected zone (HAZ) of the base metal or in the weld metal (WM). Initially the appearance of HACC was associated more closely with the HAZ of the base metal. However, recent developments in advanced steel processing have considerably improved the base material quality, thereby causing a shift of HACC to the WM itself. This represents a very serious problem for industry, because most of the predictive methods are intended for prevention of HACC in the HAZ of the base metal, not in the weld metal [1]. HACC in welded components is affected by three main interrelated factors, i.e. a microstructure, hydrogen concentration and stress level [2–4]. In general, residual stresses resulting from the welding process are unavoidable and their presence significantly influences the susceptibility of weld microstructures to cracking, particularly if hydrogen is introduced during welding [5]. Therefore various weldability tests have been developed over the years which are specifically designed to promote HACC by generating critical stress levels in the weld metal region due to special restraint conditions [4, 6–8]. These tests were used to develop predictive methods based on empirical criteria in order to estimate the cracking susceptibility of both the heat-affected zone and weld metal [4]. However, although the relationship between residual stress, hydrogen and HACC has received considerable attention, the interaction of residual stresses and microstructure in particular at microscopic scales is still not well understood [5, 9–21]. Therefore the current paper focuses on the development and assessment of techniques using Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction for the determination of local residual strains at (sub) micron scales in E8010 weld metal, used for the root pass of X70 pipeline girth welds, and their relationship to the WM microstructure. The measurement of these strains could be used to evaluate the pre-existing stress magnitudes at certain microstructural features [22].

Hydrogen Charging of High Strength Steel Specimens and Physical Simulation of Cold Cracking under Laser Beam Welding Conditions

2012 ◽  
Vol 706-709 ◽  
pp. 1391-1396
Author(s):  
Ossama Dreibati ◽  
R. Ossenbrink ◽  
Vesselin Michailov
Keyword(s):  
Laser Beam ◽  
High Strength Steel ◽  
Physical Simulation ◽  
Laser Beam Welding ◽  
High Strength ◽  
Cold Cracking ◽  
Tension Stress ◽  
Pure Hydrogen ◽  
Diffusible Hydrogen ◽  
Hydrogen Charging

Cold cracks occur during the cooling down of welded joint at low temperatures or later at room temperature after the end of welding. It is associated with the formation of brittle microstructures as martensite in the presence of diffusible hydrogen as well as of tension stresses. By using an enhanced Simulation-und Testing Center Gleeble 3500, a procedure for physical simulation of cold cracking under laser beam welding conditions is suggested. The approach reproduces combinations of the cold crack main parameters, a brittle microstructure, tension stress and high local hydrogen concentration under welding conditions which induce a cold crack. A specimen geometry and technique were developed to enable the gaseous hydrogen charging from pure hydrogen atmosphere. The amount of charged hydrogen can be adjusted through varying the charging parameters like temperature, gas pressure and charging time. The hydrogen charging technique and the cold crack testing procedure were proven with high strength steel specimens.

The Influence of Diffusible Hydrogen in Weld Metal and Moisture Content Levels in Flux Related With Weld Metal Mechanical Properties in Submerged Arc Welding Process for Line Pipe Manufacturing

2015 ◽  
Author(s):  
Gautam Chauhan ◽  
Piyush Thakor ◽  
Satyanarayana Samavedam ◽  
Ramakrishnan Mannarsamy ◽  
Ashif Sheikh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Weld Metal ◽  
Hydrogen Content ◽  
Welding Process ◽  
Diffusible Hydrogen ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Submerged Arc ◽  
Pipe Manufacturing

The mechanical properties of welding material is correlative with the diffusible hydrogen content in weld metal and level of moisture content in flux. Minitab16program to predict mechanical properties correlated to diffusible hydrogen content in weld metal and level of moisture content in flux, such as yield strength, tensile strength, elongation and average Charpy impact toughness of welding material is established by using submerged arc welding process in line pipe manufacturing. The present paper aims to experiment and investigate the line pipe SAW Flux used for offshore/onshore applications. Flux moisture content has been studied under Karl Fischer Coulometer method. Subsequently, flux was then used to make weld to analysis for ‘diffusible hydrogen content in weld metal’ through mercury displacement method. This detailed study envisages and explains the correlations between the mechanical properties and micro structures of weldments. Evaluating the variance of moisture level in flux and diffusible hydrogen content in weld metal proves the advantage of restricting the moisture content along with good practices to accomplish better weld quality.

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