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通过理化检验、裂纹形貌观察,研究了在役15X1M1Φ钢焊接接头裂纹性质及其原因。结果表明,裂纹起源于靠近熔合线的焊缝金属或热影响区粗晶区,可观察到宏观裂纹、微裂纹和空洞3种不同缺陷形貌。根据裂纹产生的位置、过程和形貌特征,可以判断该裂纹为焊接再热裂纹。焊后热处理温度场不合理产生的残余应力,焊接结构导致的强应力集中,支吊架不正常引起的附加应力,服役过程中接头塑性的降低,是导致该裂纹产生的主要原因。优化焊接和焊后热处理工艺以保证接头足够的临界塑性变形能力εc,服役过程中避免和降低应力集中和附加应力以降低接头塑性变形量εp,始终保证εc>εp,以避免具有再热裂纹敏感性的焊接接头服役过程中产生再热裂纹。
Through physical and chemical tests, crack morphology observation, the 15X1M1Φ steel welded joints in service crack nature and its causes. The results show that the cracks originate from the weld metal or the heat affected zone close to the fusion line, and three kinds of defects, macroscopical cracks, microcracks and cavities, can be observed. According to the crack location, process and topography, it can be judged that the crack is a welding reheat crack. The residual stress caused by the unreasonable temperature field of the post-weld heat treatment, the concentration of the strong stress caused by the welded structure, the additional stress caused by the improper support and hanger, and the decrease of the plasticity of the joint during service are the main reasons leading to the crack. Optimization of welding and post-weld heat treatment process to ensure adequate joint critical plastic deformation capacity εc, service process to avoid and reduce stress concentration and additional stress to reduce the plastic deformation of the joint εp, always ensure that εc> εp, in order to avoid having a reheat crack sensitive Reheat cracking occurs during service of the welded joints.