調質高張力鋼潜弧溶接熱影響部の切欠靱性と溶接軟化に関する研究(第 5 報) : 再現溶接熱影響部の切欠靱性におよぼす各種合金元素の影響

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Study was made on the effect of alloying elements on notch toughness of duplicated weld heat-affected zone heated up to 1350℃ corresponding to the thermal cycles of weld bond produced with larger heat input. Effect of alloying elements is almost similar to that clarified by the study of single-pass submerged-arc weld bond. Increased carbon decreases notch toughness of duplicated weld heat-affected zone, while nickel, manganese and chromium improve notch toughness. Increase of aluminium up to 0.16% improves notch toughness of single-cycle duplicated weld heat-affected zone contrary to the tendency in submerged-arc weld bond, which is assumed to be free from the weld metal effect. Faborable effect of aluminium on notch toughness is presumed to depend on combining effect of decreasing free nitrogen and inhibiting austenite grain growth in heat- affected zone. However, the notch toughness of multi-cycle weld heat- affected zone has suitable range of aluminium, 0.07% approximately. Small quantities of vanadium and titanium have little effect on notch toughness of duplicated weld heat-affected zone. Summing up a series of studies on single-pass submerged-arc weld bond and duplicated weld heat-affected zone, 0.08% C-0.4% Si-1.3% Mn-Ni-1.0% Cr-0.4% Mo-0.05% V-0.15% Al type steel quenched and tempered to 80kg/(mm)^2 tensile strength level is amenable to large heat input welding such as submerged-arc process.
1971-08-25