Toughness at Cryogenic Temperature and Hot Cracking in Austenitic Stainless Steel Weld Metals

Abstract

Austenitic stainless steel weld metal was studied concerning the toughness at cryogenic temperature and the hot cracking during welding. The results are as follows:
(1) By the stress relief heat treatment (SRT) the weld metals containing more than 4% of delta-ferrite are severely embrittled at -196°C. The toughness of fully austenitic weld metal through SRT was decreased with carbon increasing.
(2) The numbers of inclusions of 0.5 to less than 1.0 μ size, which are mostly detrimental to the toughness at -196°C, in the weld metal by (Ar+15% C02) shielding gas are about ten times more than one by Ar shielding gas.
(3) Fully austenitic stainless steel can attain a highly improved hot cracking resistance, almost equal to that of 304, by limiting the segregation of P, S, and Si at grain boundary on solidification.