電子ビーム溶接の欠陥発生および防止に関する研究(第 6 報) : 鋼材の深溶込み電子ビーム溶接部の欠陥発生に及ぼす母材の化学組成の影響

概要

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Effects of chemical composition of base metals (especially, C, O and Cr) on occurrence of vertical and horizontal cracks were investigated in deep penetration EBW in the flat position. Fifteen types of commercial steel plates and eight types of deposited weld metals, which contained various amounts of C, O and Cr, were used in this stydy. Penetration depths ranging from 50 to 80mm were mostly used. It was concluded that, (1) Vertical cracks were likely to occur at 0.2m/min welding speed when chemical composition of base metals was in the range of (C)≤0.25%, (O)≤220ppm and (%C)×(%O)≤2×(10)^<-3>. (2) In case of welding of low C and high O base metals, the Cr content suppressed occurrence of vertical cracks. (3) Turbulence of welding phenomena caused by CO gas emission from the molten pool was attributed to be a main reason of vertical crack formation. (4) When a base metal, of which chemical composition was in the range of (C)<0.2% and (O)<60ppm, was welded at 0.5m/min welding speed, occurrence ratio of vertical cracks increased with increase of the Cr content. This fact suggested another formation mechanism for vertical cracks. (5) In welding of killed steel, number of horizontal cracks increased with increase of the C content above 0.2%. This tendency can be explained from the Fe-C phase diagram that decrease of maximum solid solubility of S and P is mainly responsible for the cracking.
社団法人溶接学会の論文
1980-07-05