A warm stamping process of 1 and 1.2 GPa ultra-high strength steel sheets at comparatively low temperatures using rapid resistance heating was investigated to produce high strength parts. The effects of the heating temperature and rate on mechanical and surface properties of warm-stamped parts were examined. For a rapid heat rate of 100 °C/s around a heating temperature of 300 °C, the hardness of the formed parts increased from that of the as-received sheets, and the hardness for the 1.2 GPa sheet approached that of conventional hot-stamped parts from 22MnB5 steel sheets. The increase in hardness appeared only for rapid heating, and not for slow heating using a furnace. The increase in hardness is due to the transformation of retained austenite into martensite at comparatively low temperatures using rapid resistance heating and cooling. For the comparative low heating temperature, the non-coated sheet hardly oxidised, and the galvannealed sheet having high corrosion resistance did not exhibit the exfoliation of the coating layer, whereas the springback did not improve.

研究了使用快速电阻加热在相对较低的温度下对1和1.2 GPa超高强度钢板进行的热冲压工艺，以生产高强度零件。研究了加热温度和加热速率对热冲压零件的机械性能和表面性能的影响。在300°C的加热温度下以100°C / s的快速加热速率，成型零件的硬度比原先的板高，而1.2 GPa板的硬度接近传统的热轧板。由22MnB5钢板冲压而成的零件。硬度的增加仅出现在快速加热中，而没有出现在使用炉子的缓慢加热中。硬度的增加是由于使用快速电阻加热和冷却方法在相对较低的温度下将残余奥氏体转变为马氏体的缘故。