摘要
某石油机械厂生产的35CrMo钢无缝直管在远低于设计压强的水压试验中发生纵向开裂,通过对送检的直管进行化学分析、显微组织观察、裂纹及断口形貌观察、硬度测试等检验,查明了开裂的原因。结果表明,开裂的主要原因是脱碳层导致直管外壁的屈服强度降低、调质后直管外壁有较大拉应力以及在水压试验中外壁承受拉应力的综合作用。此外,由于35CrMo钢无缝直管在淬火加热过程中表面脱碳和回火不充分,使得试样内、外壁和芯部的硬度不能满足工艺设计的要求。
35CrMo steel seamless straight pipe produced by a petroleum machinery factory cracked during the hydrostatic test at far below design pressure. The cracking causes was found out by chemical analysis,metallographic examination,morphology observation of crack and fracture. The results show that the predominant cause of cracking is the combined action caused by the decarburized layer leading to lower yield strength on outer surface of the straight pipe and larger tensile stress on outer surface of the straight pipe after quenching and tempering,as well as outer surface bearing tensile stress during hydrostatic test. In addition,the surface decarburization of 35 CrMo steel seamless straight pipe during the heating of quenching and inadequate tempering make the hardness on the outer and inner surface and in core can not meet the requirements of process design.
出处
《热处理技术与装备》
2016年第4期49-52,共4页
Heat Treatment Technology and Equipment
关键词
35CrMo钢无缝直管
纵向开裂
淬火
回火
35CrMo steel seamless straight pipe
longitudinal cracking
quenching
tempering
