フェライト単相で凝固するCr-Ni系ステンレス鋼溶接金属の凝固・変動挙動

Cr-Ni系ステンレス鋼溶接金属の凝固・変態に関する研究(第4報)

抄録

In Fe-Cr-Ni stainless steel weld metals which solidify as ferritic single phase, austenite first precipitates at ferrite grain boundaries on cooling. Then continuous intergranular austenite is formed by the coalescence of globular austenite along grain boundaries. The austenite has the K-S relationship with ferrite of both side, selecting different combinations of close-packed plane and direction for each ferrite. Subsequently, Widmanstatten austenite, which has the same cystallographic characteris-tics of the intergranular austenite, grow into the ferrite grain. In duplex stainless steel weld metals containing nitrogen, intragranular austenite precipitates after the formation of intergranular austenite. Diffusion of nitrogen primarily controls the precipitation of both inter- and intragranular austenite. With increasing Cr and Ni contents, the precipitation of the intragranular austenite increase due to the increase in microsegregation during solidification.