Numerical analysis on solidification cracking susceptibility of type 316 stainless steel considering solidification mode and morphology computer simulation of hot cracking by solidification/segregation models

摘要

The two-phase solidification model was constructed considering the solidification mode and morphology. The effects of the solidification mode and morphology as well as δ-ferrite on the solidification cracking susceptibility of austenitic stainless steels (SUS316L) were clarified by a numerical analysis. The solid-liquid coexistence temperature range (SLCTR), correlating the solidification brittle temperature range (solidification cracking susceptibility), was calculated based on the computer simulation of supercooling and solidification segregation behaviours. In the peritectic-eutectic solidification model, the solidification mode greatly influenced the solidification segregation as well as the SLCTR, although the solidification segregation and the SLCTR would be discontinuously changed at the solidification mode transition. The SLCTR calculated by peritectic-eutectic solidification model was larger than that by divorced eutec-tic solidification model at the ferritic-austenitic mode solidification, while an opposite tendency was observed at the austenitic-ferritic mode solidification. The amounts of 6-ferrite calculated by each solidification model were comparable in any solidification modes. The SLCTR was approximately decreased with an increase in the amount of 6-ferrite in any solidification models. It followed that solidification cracking susceptibility would be dom-inantly influenced by δ-ferrite and additionally by the solidification mode and morphology.