摘要
某公司的304不锈钢管道在焊接过程中发生了开裂,裂纹位于焊接热影响区。在排除焊接对失效的影响后,对该管道进行了化学成分、力学性能、晶间腐蚀检测,都未发现异常。通过模拟焊接工况的方法,在失效管正常位置制备新裂纹。对新裂纹进行宏观观察、金相分析、扫描电镜分析以及EDS能谱分析,推断出原焊接热影响区开裂的原因为液态金属致脆。管道表面加工过程中采用了含锌涂料,在焊接过程中,表面熔化的液态锌渗透到管材内部,使得材料晶界弱化。在焊接热影响区,受焊接热应力的作用,裂纹在晶界处起裂并最终导致该管道沿晶开裂。
A 304 stainless steel pipe of a company cracked during welding. Cracks were located in heat-affected zone of welding. Eliminating the influence of welding, no abnormalities were found after the chemical composition, mechanical properties and intergranular corrosion tests of the pipeline. By the simulation of the welding condition, new cracks in normal position of failed pipe were prepared. Macroscopic observation, metallographic analysis, scanning electron microscope and energy spectrum analysis of new cracks were carried out. It is deduced that liquid metal embrittlement is the main cause of cracking of original welding heat affected zone. The Zn-containing coating is used in the surface processing of pipeline.During welding, molten Zn penetrates into the interior of the pipe, which leads to the weakening of grain boundary. In the heat affected zone of welding, due to welding thermal stress cracks initiate at grain boundaries and eventually lead to intergranular cracking of pipe.
作者
江涛
关凯书
JIANG Tao;GUAN Kaishu(School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《热加工工艺》
北大核心
2021年第15期158-161,共4页
Hot Working Technology
关键词
304不锈钢
焊接热影响区
液态金属致脆
失效分析
304 stainless steel
heat-affected zone
liquid metal embrittlement
failure analysis
