Experimental study on cryogenic temperature fracture toughness of 19Cr-17 Ni-5Mn-4Mo austenitic stainless steel weld metal
In order to solve the problem of low and unstable fracture toughness of weld metal at 4.2 K cryogenic temperature of 19Cr-17 Ni-5Mn-4Mo austenitic stainless steel in D-coil box of Tokamak nuclear fusion device,welding test was performed under different welding heat input,weld bead layout,inter-pass temperature and cleanliness control,and the influence of those weld-ing variables on the cryogenic temperature fracture toughness of weld metal were explored.The in-ternal relationship between microstructure and cryogenic temperature fracture toughness was stud-ied by metallographic analysis,EBSD and fracture SEM,which provides a theoretical basis for op-timizing welding process.The results show that the cryogenic temperature fracture toughness of weld metal can be effectively improved by lowing the welding heat input and inter-pass tempera-ture to refine the grain and reduce the precipitated phase,and by improving the quality of shiel-ding gas protection of TIG welding,strengthening the inter-pass cleaning and optimizing the weld bead layout to improve the purity and uniformity of weld.
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