回火温度对超低碳贝氏体钢(ULCB)组织与性能的影响

Effect of Tempering Temperature on Microstructure and Mechanical Properties of Ultra Low Carbon Bainite Steels

超低碳贝氏体钢经两阶段控轧控冷,在不同温度进行一定时间的回火,检测了热处理前后钢板力学性能并对比分析了组织特点。结果表明,随着回火温度的升高,贝氏体板条逐渐合并,过渡到粒状贝氏体,随着回火温度的进一步升高,出现粗大的准多边形铁素体组织;在490℃～620℃范围内进行热处理,试验钢会得到良好的综合性能;粒状贝氏体组织在-20℃的低温冲击功在560℃热处理达到最小值,之后随着回火温度的升高而大幅提高;而含有板条贝氏体组织钢的-20℃低温冲击功随着热处理温度的升高而有所改善。

Ultra low carbon bainite （ULCB） steels were tempered at different temperature after controlled rolling and controlled cooling,mechanical properties of the ULCB steels before and after being tempered were tested and their microstructures were also compared.The results show that the bainitic lath will gradually merge and granular bainite may appear with increasing tempering temperature.Coarse quasi-polygonal ferrite will form at a higher temperature.The tested steels tempered at 490 ℃～620 ℃ can gain favorable comprehensive mechanical properties.The impact energy at -20 ℃ of the tested steels with granular bainite reach minimum when tempered at 560 ℃ and increase significantly with increasing the tempering temperature.However the impact energy at -20℃ of the tested steels with bainitic ferrite will increase with increasing the tempering temperature.