主蒸汽压力取样管异种钢焊接接头开裂原因分析  

Analysis on cracking of dissimilar material welded joint of main steam pressure sampling tube

作　　者：王飞 杨超[2] 张立代 石仁强 WANG Fei;YANG Chao;ZHANG Lidai;SHI Renqiang(Jiangsu Zhenjiang Gas Thermoelectric Co.,Ltd.,Zhenjiang 212028,China;Jiangsu Frontier Electric Technology Co.,Ltd.,Nanjing 211102,China)

机构地区：[1]江苏镇江燃气热电有限公司,江苏镇江212028 [2]江苏方天电力技术有限公司,江苏南京211102

出　　处：《物理测试》2023年第6期50-55,共6页Physics Examination and Testing

摘　　要：为了避免发生机炉外小径管爆裂事故,以某电厂一次P91材质机外管异种钢焊接接头开裂为例,通过宏观检查、光谱分析、断口分析、金相分析、硬度检验以及管系应力分析对开裂原因进行了分析。结果显示:该取样管异种钢焊接接头失效机制为应力腐蚀开裂,且呈沿晶脆性断裂形态。保温层不严密致雨水流到管表面形成腐蚀环境,角焊缝焊址处二次应力严重超标,是导致管接头开裂的主要外在因素;管段硬度严重超标,组织异常,焊口未做焊后热处理,管接头热影响区脆性大,是导致管接头开裂的主要内在因素。In order to avoid the occurrence of small pipe explosion accident outside the furnace,the cracking of dissimilar material welded joint of P91 material outside the machine pipe was taken as an example.The reasons for the cracking were analyzed through macroscopic examination,spectral analysis,fracture analysis,metallographic examination,hardness test and pipe stress analysis.The results showed that the failure mechanism of dissimilar material welded joint of sampling tube was the stress corrosion cracking,and it had the morphology of brittle fracture along the grain boundary.The rainwater flowed on the surface of tube due to the loose insulation layer,which formed the corrosion environment.The secondary stress at the position of fillet weld seriously exceeded the standard,which was the main external factor to cause joint cracking.The hardness of tube also severely exceeded the limit.Moreover,the abnormal structure,lack of post-weld heat treatment in joint,and high brittleness of heat affected zone were main internal factors to cause joint cracking.

关 键 词：P91钢管 焊接接头 断裂 应力腐蚀开裂 二次应力 硬度 

分 类 号：TG407[金属学及工艺—焊接] TG115