Structural variations in heat treated B-bearing stainless steel

The aim of the present study is to investigate the effects of austenitizing temperature on the microstructures, hardness and impact toughness of austenitic stainless steel containing 1.5–2.5 wt.% B. It is observed that the phases present in the heat treated B-bearing stainless steel are austenite and M2(B, C) borocarbide and the M2(B, C) borocarbide has no obvious change when the austenitizing temperature is lower than 950 °C. When the austenitizing temperature exceeds 950 °C, parts of the borocarbide networks are broken, and some isolated borocarbides appear. Moreover, there is no significant change in the borocarbide volume fraction unless the austenitizing temperature is beyond 1050 °C. As the austenitizing temperature exceeds 1050 °C, the borocarbide volume fraction decreases. The microhardness of metallic matrix and Vickers hardness of B-bearing stainless steel increase with the increase of austenitizing temperature, and the microhardness of borocarbides has no obvious change at different austenitizing temperature. The change of austenitizing temperature has no obvious effect on the impact toughness of B-bearing stainless steel also.