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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。
The characteristic values of crack tip open displacement (CTOD) of the welded joints of the spherical tank steel BP460NLI were measured by the multi-sample resistance curve method and the cross-sectional method. The CTOD value of crack initiation reached when the crack tip extension reached saturation. Weld, fusion line and heat affected zone. The microstructure and fracture morphology of welded joints were observed by optical microscope and scanning electron microscope. The results show that the weakness of the fracture toughness of the welded joint is in the overheated zone of the near fusion line in the heat affected zone (HAZ). The coarse Widmanstatten organization and part of the “tissue genetic” phenomenon in this zone are the main causes of the low toughness embrittlement.