Abstract：High toughness and ultra high strength marine engineering steel can reduce the weight of marine equipment itself and save energy，but it requires good strengthtoughness matching for this kind of steel application，and quenching process significantly affects its subsequent phase transformation and mechanical property. Effects of quenching process on the microstructure and mechanical properties of Cubearing ultrahigh strength marine engineering steel were investigated depending on low carbon (w(C)<0.05%) design by optical microscopy，scanning electron microscopy and transmission electron microscopy. The results showed that the highest peak hardness was 386HV at 450 ℃ aging after 910 ℃ quenching，and the partial secondary martensite microstructure was attained at 700 ℃ aging by air cooling，and the peak hardness was 357HV. The average precipitation radius of the copperrich phase was around 5 nm under 525 ℃ aging，which gave rise to a higher strengthening increment. When quenched at 820-910 ℃，grains and martensite lath blocks of Cubearing steel were refined with decreasing quenching temperature，which improved grain boundary density of low angle in the matrix，resulting in the increment of strength and toughness. The highest strength reached 1 109 MPa at 820 ℃ quenching，and -80 ℃ impact toughness was 91 J.
李振团，柴锋，杨才福，罗小兵，苏航. 淬火工艺对铜沉淀强化UHS钢组织性能的影响[J]. 钢铁, 2019, 54(6): 79-85.
LI Zhentuan，CHAI Feng，YANG Caifu，LUO Xiaobing，SU Hang. Effect of quenching process on microstructure and mechanical properties of Cu precipitated hardened ultrahigh strength steel. Iron and Steel, 2019, 54(6): 79-85.
