X80M 钢级管道自动焊环焊缝裂纹成因分析
Cause analysis of girth weld cracking in automatic welding for X80M pipeline steel
李曾珍 1杨叠 1代晓波 2鹿锋华 1李彦龙 2闫新宇1
作者信息
- 1. 中国石油天然气管道科学研究院有限公司,河北廊坊 065000;油气管道输送安全国家工程研究中心,河北廊坊 065000
- 2. 曹妃甸新天液化天然气有限公司,河北唐山 063200
- 折叠
摘要
管径1 422 mm、高钢级X80M某管线工程的自动焊环焊缝经现场无损检测发现疑似裂纹,打磨验证后确认为裂纹缺陷.为了探究X80M管线钢环焊缝出现裂纹的原因,通过钢管和焊接材料化学成分分析、裂纹无损检测定位、裂纹缺陷切割,以及裂纹宏微观形貌及组织、显微硬度、裂纹及裂纹附近区域分析等试验方法,确定了裂纹的形成原因.分析结果表明:裂纹位于焊缝填充层,裂纹附近的基体富集Cu元素,以等轴晶为主,其周围显微硬度值明显高于远离裂纹的焊缝,且裂纹沿着晶界扩展,裂纹内部及其附近区域均存在Cu.结合现场施焊信息,在填充焊接过程中,铜质导电嘴与坡口壁接触而发生短路,短路电流产生的高温使铜质导电嘴与坡口壁接触部分烧熔,熔化的Cu进入焊缝,并沿着焊缝晶界扩散而形成Cu富集区,导致环焊缝熔铜开裂.
Abstract
The suspected cracking of girth weld cracking in automatic welding was found in site non-destruc-tive testing for one pipeline engineering of high-grade X80M steel with pipe diameter of 1 422 mm.In order to analyze the causes for the girth weld cracking in automatic welding of X80M pipeline steel,a series of test methods were employed to find out the formation reason of cracking,including chemical composition a-nalysis of steel pipe and welding material,non-destructive testing positioning of cracking,cutting of crack-ing defects,macro and micro morphology and structure observation of cracking,microhardness,analysis of cracking and nearby regions.The analysis results showed that the cracking was located on the filling layer of weld joint.Cu was enriched in the nearby matrix of cracking,which was mainly in isometric crystal.The surrounding microhardness was obviously higher than the weld which was far away from the cracking.Mo-reover,the cracking was extended along with the grain boundary.Cu was found inside of cracking and sur-rounding areas.Combined with welding information in site,the copper contact tube contacted with groove wall in the process of filler welding,leading to short circuit.The high temperature due to the short circuit caused the hot melting of contact position between copper contact tube and groove.The molten Cu entered the weld and diffused along the grain boundary,resulting in Cu enrichment area and cracking of the girth weld.
关键词
X80M管线钢/自动焊/环焊缝/裂纹成因/熔铜开裂Key words
X80M pipeline steel/automatic welding/girth weld/cause of crack/molten copper cracking引用本文复制引用
出版年
2024
NETL
NSTL
万方数据