【摘要】 用多试样阻力曲线法和剖面法测定了球罐钢BP460NLI焊接接头的裂纹尖端张开位移(CTOD)特征值,得出了裂尖伸张区达到饱和时的启裂CTOD值乩在母材、焊缝、熔合线和热影响区中的分布,并用金相显微镜和扫描电镜观察了焊接接头各区的显微组织和断裂形态。结果表明,焊接接头断裂韧性的薄弱环节在热影响区(HAZ)近熔合线的过热区,该区中粗大的魏氏组织和部分“组织遗传”现象是导致低韧性脆化的主要原因。更多还原

【Abstract】 The characteristic values of crack tip opening displacement (CTOD) for welded joints of BP46ONLI steel plates used for the oxygen global vessel were measured by the methods both the multispecimen resistance curve and metallographical profile. And the distributive graph of saturated initiating δ for crack tip at the base metal, weld metal, bond line and HAZ of welded joints was determined here. Some microstructures and fracture patterns at welded joints were observed by using metaloscope and SEM. The testing results showed that the weakest fracture toughness of welded joints was at the overheated zone of HAZ nearing the bond line, and the low toughness brittle failure was caused by the existance of the widmanstatten structure and structural heredity of HAZ.更多还原