摘要
为了研究埋弧焊管焊接接头背面导向弯曲失效原因,采用宏观分析、金相试验、冲击试验、超声波和射线检测等手段,从焊材匹配、焊接热输入、塑性变形、试样制备、时效处理以及夹杂物等方面进行了分析和研究。结果表明,背弯焊缝开裂主要原因:一是焊接接头与母材强度不匹配,造成局部集中变形超过焊缝塑性变形极限;二是焊接热输入过大,内应力过大造成弯曲过程中焊缝表面龟裂。背弯焊趾开裂主要原因:一是热影响区金属软化,造成弯曲过程集中塑性变形超过该区域金属的塑性变形极限;二是局部管形不规则(如过大的噘嘴和焊缝余高),造成扩径和试样压平过程中在焊趾处产生强烈的应力集中。根据研究结果,建议制造商从原料订货技术协议要求、焊接工艺设计、试验检测过程控制及无损检测等多方面采取相应措施,解决弯曲失效问题。
In order to study the failure cause of back guided bending of submerged arc welded pipe joint,macro analysis,metallographic test,impact test,ultrasonic and radiographic testing were used to analyze and study the welding material matching,heat input,plastic deformation,sample preparation,aging and inclusions.The results show that the main reasons for back bend weld cracking are as follows:first,the strength of the welded joint does not match that of the base metal,resulting in the local concentrated deformation exceeding the plastic deformation limit of the weld;the second is that the welding heat input is too large,and the internal stress is too large,which causes the weld surface cracking in the bending process.The main reasons for the back bend toe cracking are as follows:first,the metal in the heat affected zone softens,resulting in the concentrated plastic deformation exceeding the plastic deformation limit of the metal in the zone;the second is the irregular shape of local pipe(such as excessive angular distortion and weld reinforcement),which results in strong stress concentration at the weld toe in the process of expanding and sample flattening.According to the research results,it is suggested that the manufacturer take corresponding measures from the requirements of the technical agreement for raw material ordering,welding process design,process control of test and detection and nondestructive testing to solve the bending failure.
作者
张志明
高广俊
印乐
汪超
ZHANG Zhiming;GAO Guangjun;YIN Le;WANG Chao(Bohai Equipment Jiangsu Steel Pipe Company,Nanjing 210001,China)
出处
《焊管》
2021年第7期59-64,68,共7页
Welded Pipe and Tube
关键词
埋弧焊管
导向弯曲
塑性变形
热影响区软化
应力集中
submerged arc welded pipe
guided bending
plastic deformation
heat affected zone softening
stress concentration
