부산대학교 도서관

In this study, austenite formation in 201 austenitic stainless steel was observed in two steps during solidification. Initially, austenite (γ1) precipitated and grew on δ-ferrite during the peritectic reaction (δ + liquid → γ1) and formed directly from the residual liquid (γ2). With the addition of Co, from 0.09 to 0.51 wt.%, the dendrite morphology of ferrite changed from columnar dendritic to equiaxed dendritic. Primary ferrite phase morphology changes resulted in an austenite microstructure composed of a uniform dispersion of fine grains. Both ε-martensite (hcp) and α′-martensite (bct) were present in the microstructure due to the deformation of austenite particles by the impact force. The impact toughness increased by 33% as the cobalt content increased to 0.51 wt.%.