淬火温度对E550海洋工程用钢组织与性能的影响

对控轧控冷态60 mm厚的E550海洋工程用钢分别进行860、890、930℃的奥氏体化淬火,650℃的回火,使用扫描电子显微镜和电子背散射衍射技术对热处理后钢板的组织和力学性能进行研究。结果表明:调质处理钢板的屈服强度随着淬火温度的升高不断增加,而抗拉强度和伸长率基本保持不变。860℃淬火后的组织细小均匀,晶内有大量小角度晶界存在,冲击吸收能量在188～335 J之间;890℃淬火,晶粒尺寸有所增加,且晶粒间多以大角度晶界为多;930℃淬火,由于温度较高,相邻奥氏体晶粒间出现相互吞并生长现象,冲击吸收能量很不稳定,最低仅为20 J。

Effect of quenching temperature on microstructure and properties of E550 ocean engineering steel

The TMCP 60 mm thick E550 ocean engineering steel plates were quenched at 860 ℃,890 ℃ and 930 ℃ respectively and then tempered at 650 ℃,after that,the microstructure and mechanical properties of the steel plates was investigated by SEM and EBSD.The results show that with the increasing of quenching temperature,the yield strength of the steel plates is increased,while the tensile strength and elongation remain unchanged mainly.After quenching at 860 ℃ and tempering at 650 ℃,the steel plate has fine and homogeneous microstructure and lots of small angle grain boundaries with good impact toughness;when the quenching temperature is increased to 890 ℃,grain size is increased and large angle grain boundaries are dominated;when the quenching temperature is increased to 930 ℃,neighbouring austenite grains grow and combine,therefore the impact toughness is deteriorated,the lowest value is 20 J.