scholarly journals Comprehensive Analysis of Cold-Cracking Ratio for Flux-Cored Arc Steel Welds Using Y- and y-Grooves

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5349
Author(s):  
Hyunbin Nam ◽  
Jaeseok Yoo ◽  
Kwanghee Yun ◽  
Guo Xian ◽  
Hanji Park ◽  
...  
Keyword(s):  
Hydrogen Content ◽  
High Strength ◽  
Cold Cracking ◽  
Carbon Equivalent ◽  
Diffusible Hydrogen ◽  
Factors Affecting ◽  
Strength Grade ◽  
Groove Shape ◽  
Weld Metals ◽  
Steel Welds

This study investigates various factors that influence the cold-cracking ratio (CCR) of flux-cored arc welds through Y- and y-groove tests. Factors affecting the CCR include the alloy component, diffusible hydrogen content, microstructure, hardness, and groove shape. In weld metals (WMs; WM375-R and WM375-B) of a low-strength grade, the diffusible hydrogen content has a more significant effect on the CCR than the carbon equivalent (Ceq) and microstructure. However, the combined effects of the microstructure and diffusible hydrogen content on the CCR are important in high-strength-grade WM. The CCR of the WM increased upon increasing Ceq and the strength grade because hard martensite and bainite microstructures were formed. Moreover, y-groove testing of the 500 MPa grade WM revealed a more significant CCR than that of the 375 MPa grade WM. Therefore, in high-strength-grade WMs, it is necessary to select the groove shape based on the morphology in the real welds.

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 Effect of Electrode Waterproof Coating on Quality of Underwater Wet Welded Joints

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2947 ◽  
Author(s):  
Jacek Tomków ◽  
Dariusz Fydrych ◽  
Kamil Wilk
Keyword(s):  
Hydrogen Content ◽  
Welded Joints ◽  
High Strength ◽  
Industrial Applications ◽  
Cold Cracking ◽  
Diffusible Hydrogen ◽  
Deposited Metal ◽  
Covered Electrodes ◽  
Steel Joints

In this paper, the effects of different hydrophobic coatings on the surface of covered electrodes on the quality of wet welded carbon steel joints were discussed. Commonly available hydrophobic substances used in industrial applications were selected for the research. The aim of using waterproof coatings was to check the possibility to decreasing the susceptibility of high-strength low-alloy S460N steel to cold cracking. During experiments diffusible hydrogen content in deposited metal determination by mercury method, metallographic macro- and microscopic testing and hardness measurements were performed. Investigations showed that waterproof coatings laid on covered electrodes can improve the quality of wet welded joints, by decreasing the Vickers HV10 hardness in heat-affected zone and decreasing the diffusible hydrogen content in deposited metal, which minimalize possibility of cold cracking.

Integrated Experimental Procedures Assessing Hydrogen Induced Cracking Susceptibility

2015 ◽  
Author(s):  
Ahmed Fotouh ◽  
R. El-Hebeary ◽  
M. El-Shennawy ◽  
David Tulloch ◽  
Jason Davio ◽  
...  
Keyword(s):  
Base Metal ◽  
Hydrogen Content ◽  
Hsla Steel ◽  
High Strength ◽  
Carbon Equivalent ◽  
Mapping Technique ◽  
Static Fatigue ◽  
Diffusible Hydrogen ◽  
Hydrogen Induced Cracking ◽  
Implant Test

This study proposes a complete set of integrated experimental procedures to assess the risk of Hydrogen Induced Cracking (HIC) using implant test. The proposed experimental procedures assess HIC susceptibility in base metals using two measures: the implant static fatigue limit stress (σimp); and Heat Affected Zone (HAZ) maximum hardness (HV10MAX). The base metal susceptibility to HIC was evaluated by examining the effect of three welding factors: the critical cooling time between 800 °C and 500 °C (t800/500); the base metal carbon equivalent (CE); and the diffusible Hydrogen content (H). A 3-D mapping technique was used to demonstrate the interactive integrated relationships among the three examined welding factors (i.e. t800/500, CE and H) and the susceptibility of the base metal to HIC. Using the 2-D projection of the developed 3-D mapping, it was proven that the diffusible hydrogen content (H) had more effect on the HIC susceptibility of High Strength Low Alloy (HSLA) steel compared to the effect of H on the HIC susceptibility of Carbon-Manganese (C-Mn) steel.

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.

Weld Metal Hydrogen Cracking in Transmission Pipelines Construction

2010 ◽  
Author(s):  
Sheida Sarrafan ◽  
Farshid Malek Ghaini ◽  
Esmaeel Rahimi
Keyword(s):  
Weld Metal ◽  
Construction Projects ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Equivalent ◽  
Transverse Cracks ◽  
Diffusible Hydrogen ◽  
Hydrogen Cracking ◽  
Girth Welds ◽  
Welding Position

Developments of high strength steels for natural gas pipelines have been in the forefront of steelmaking and rolling technology in the past decades. However, parallel to such developments in steel industry, the welding technology especially with regards to SMAW process which is still widely used in many projects has not evolved accordingly. Decreasing carbon equivalent has shifted the tendency of hydrogen cracking from the HAZ to the weld metal. Hydrogen cracking due to its complex mechanism is affected by a range of interactive parameters. Experience and data gained from field welding of pipeline construction projects indicated that weld metal hydrogen cracking is related to welding position as it occurs more in the 6 o’clock position of pipeline girth welds. In this research an attempt is made to open up the above observation in order to investigate the contributory factors such as welding position and welding progression in terms of diffusible hydrogen and possibly residual stress considerations. It was observed that transverse cracks produced in laboratory condition may not be detected by radiography. But, the higher tendency for cracking at 6 o’clock position was confirmed through bend test. It is shown that more hydrogen can be absorbed by the weld metal in the overhead position. It is shown that welding progression may also have a significant effect on cracking susceptibility and it is proposed that to be due to the way that weld residual stresses are developed. The observations can have an important impact on planning for welding procedure approval regarding prevention of transverse cracking in pipeline girth welds.

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