20G锅炉管拔口开裂原因分析  

Cause Analysis on Pull-Out Crack of 20G Boiler Tube

作　　者：左国锋 彭先明[1] ZUO Guofeng;PENG Xianming(Hengyang Valin Steel Tube Co.,Ltd.,Hengyang 421001,China)

机构地区：[1]衡阳华菱钢管有限公司,湖南衡阳421001

出　　处：《锅炉技术》2021年第5期51-55,共5页Boiler Technology

摘　　要：某公司在用20G锅炉管加工管件时发生了拔口开裂,为研究开裂原因,对开裂区材料进行化学成分分析、金相分析、断口宏观和微观分析、扫描电镜和能谱分析,并结合管材拔口工艺进行讨论。研究发现开裂区化学成分中有超量的Cu元素,且微观观察发现裂纹中有大量铜黄色物质。结果表明:20G锅炉管拔口开裂的根本原因为钢管外表Cu污染。Cu元素弱化了晶间强度,拔口时在高温和拉应力的作用下由管体外表面开始沿晶脆性开裂并迅速向内表面扩展,最终裂开。Pull-out cracking has been found when processing pipe fittings with 20G boiler tubes,in order to study the cause of the cracking,chemical composition analysis,metallographic analysis,fracture macro and micro analysis,scanning electron microscope and energy dispersive spectrometer analysis were carried out on the materials in the cracked area,combined with the pipe pull-out process.Analysis found that there was an excessive amount of Cu in the chemical composition of the cracked zone,and microscopic observation revealed that there was a large amount of copper yellow substance in the crack.The results indicate that the root cause of the 20G boiler tube pull-out crack is Cu pollution on the surface of the steel tube.The Cu element weakens the intergranular strength.Under the action of high temperature and tensile stress,the outer surface of the tube begins to undergo brittle cracking and rapidly expand to the inner surface,and eventually cracks.

关 键 词：锅炉管 脆性开裂 CU污染 碳弧气刨 

分 类 号：TK223.3[动力工程及工程热物理—动力机械及工程]