Abstract
Solidification mode in laser welds sometimes exhibits the primary austenite, which enhances hot cracking suceptibility, because of an austenitizing effect of nitrogen and the high solidification rate. Therefore, laser welds of high nitrogen stainless steels likely occurs hot cracking. This investigation was conducted to clarify effects of nitrogen and solidification rate on hot cracking susceptibility in laser welds of austenitic stainless steels varied with nitrogen contents. Hot cracking susceptibility in laser welds was markedly increased with increase in the solidification rate and nitrogen contents. On the other hand, solidification mode in weld metals was changed from primary ferrite to primary austenite, as raising the solidification rate and the nitrogen content in laser welds. Experimental results indicated that the abrupt increase in hot cracking susceptibility is consistent with transition in the solidification mode from primary ferrite to primary austenite in the weld metal. The transition of solidification mode from primary ferrite to primary austenite in laser welds could be estimated by calculation using the modified KGT model considering the effect of nitrogen. These results suggest that hot cracking susceptibility in laser welds of the steels can be also predicted by using the same analytical method of solidification mode in the welds.
Published Version
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