海绵钛还原罐焊缝开裂原因及防止措施

Weld crack causes and prevention of weld cracking the reduction jar of titanium sponge

海绵钛还原罐工况恶劣,焊缝受力大,使用一段时间部分罐体焊缝开裂。通过取样分析,还原罐材质为18-8型奥氏体不锈钢,裂纹产生于罐体外侧,焊缝开裂与还原罐工作温度高、焊缝受力太大、制造过程中焊接热输入太大导致的焊缝晶粒粗大密切相关。还原罐喷淋冷却过程中,在水蒸汽与氯离子(Cl-)的共同作用下,加速了罐体的腐蚀和裂纹扩展。采取在还原罐下加支撑,减小焊缝受力,采用小线能量焊接,控制层间温度等措施,能降低还原罐焊缝开裂倾向,延长还原罐的使用寿命,降低海绵钛生产成本。

The reduction jar of titanium sponge production is under a bad working condition,and the weld seam is under a large stress, ~ after a period time of using,section of the weld seam on the tank will be cracked. By analysis of samples,we learn that the reduction jar was made of 18-8 austenitic stainless steel,crack occurred on the lateral of tanks. There was a close relationship between the weld seam cracks and highly working temperature ,large force the weld seam pressured, coarse grain during the welding process. At the same time, under the combined action of water and chloride （CF） during the spray cooling process,accelerated the corrosion of tanks and crack propagation. Measures should be taken such as adding some supports under the reduction jars,reducing the weld stress,using lower welding line energy,and controlling the interpass temperature,etc,to reduce the tendency to weld seam cracks,and extend its service life, and reduce the costs.