Weld Cold Cracking in HAZ of Engineering Carbon and Low Alloy Steel (Report I) : Behavior of Cracking in the RRC Test of SNCM439 and SK5(Materials, Metallurgy & Weldability)

概要

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In order to investigate the weld cold cracking of engineering carbon and low alloy steels which is considered to be caused by quenching crack, the fundamental behaviors of this type of cracking were studied by means of the RRC test. HAZ cracking in JIS SNCM439 and JIS SK5 was studied under the conditions of the restraint intensity of about 9.8 to 29.4kN/mm・mm without preheating utilizing GTA welding with austenitic filler wire to eliminate the effect of diffusible hydrogen in the weldment. As a result, test materials used in this investigation showed very high crack susceptibility and the stress at crack initiation was about 400 and 270MPa in SNCM439 and SK5, respectively, irrespective of the restraint intensity. It was confirmed, therefore, that quenching crack is susceptible in the welding of these steels. Additionally, the location of crack initiation had a close relation with liquated grain-boundary in HAZ near fusion boundary.
大阪大学の論文