速度依存性を考慮したオーステナイト系ステンレス鋼溶接凝固過程の数値解析

－オーステナイト系ステンレス鋼溶接金属凝固組織の解析－

抄録

A numerical model to predict the solidification microstructure and solidification cracking susceptibility of austenitic stainless steel weld metal is proposed by taking into account the non-equilibrium theory. It was predicted using the developed numerical model that Fe-20Cr-14.4Ni, Fe-20Cr-12.7Ni, Fe-20Cr-11.5Ni and Fe-20Cr-9.8Ni weld metals solidified as A mode (L→L +γ→γ), AF mode (L→L +γ→L +γ+δ→γ+δ), FA mode (L→L +δ→L +δ+γ→δ+γ) and FA mode, respectively. Also, it was found that the effect of Ni content on the solidification cracking susceptibility of Fe-20Cr-(9.8-14.4)Ni weld metal, determined via Trans Varestraint testing, agreed with the results calculated using the model. Furthermore, it was found that the content of δ ferrite at just solidifying calculated using the model agreed with the results measured using Fe-20Cr-(11.5-14.4)Ni weld metals quenched in liquid Sn. These agreements support the validity of the developed numerical model.