A large number of surface cracks occurred after the welding of stainless steel heat exchanger tube plate and heat exchange tube.In order to find out the cause and mechanism of crack formation,the failure analysis of equipment materials was carried out by means of macroscopic inspection,self-melting and filling wire welding comparative test,chemical composition analysis,metallographic inspection and SEM-EDS.The results show that slag formation is insufficient in the process of smelting and deoxidation,and a large number of non-metallic inclusions such as alumina and calcium oxide remain.In the welding process,heat input causes the non-metallic inclusions to accumulate in the weld center or arc pit in the weld pool,resulting in a large number of surface cracks in the crystallization process of the weld metal,and the existence of residual stress makes the cracks expand further.
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