Abstract: The tested steel M54 (/%：0.28~0.32C, ≤0.10Si, ≤0.10Mn, ≤0.005S, ≤0.008P, 9.5~10.5Ni, 6.6~7.4Co, 1.8~2.2Mo, 1.1~1.5W, 0.7~1.3Cr, 0.04~0.16V) is melted by 5.8t vacuum induction furnace +2.2t vacuum consumable electrode furnace, and forged to Ф170mm bar products. The Ф5mm test specimens cut at 1/2R of forged bar are treated by solid solution treatment at 1075°C for 90min, air cooling and at 1060℃ for 75min, oil cooling + deep-cooling treatment at -73 for 120min + aged treatment at 400~600℃ for 300min, air cooling. The effect of aging temperature on mechanical properties and structure of secondary-hardening ultra-high strength steel M54 is studied and analyzed by optical and scanning electron microscope etc. Results show that tested steel M54 aged at 520°C for 300min has excellent comprehensive mechanical properties-tensile strength 2040MPa, impact energy 62J and fracture toughness 110MPa·m^1/2；with aging at 560°C the morphology of intergranular fracture occurs in steel and the impact energy K_U2 and fracture toughness K_IC of the steel decrease respectively to 26J and 80.6MPa·m^1/2 , and with increasing aging temperature to 600°C the impact energy K_U2 and fracture toughness K_IC of tested steel increase respectively to 56J and 131MPa·m^1/2.

摘要： 试验用M54钢（/%:0.28~0.32C,≤0.10Si,≤0.10Mn,≤0.005S,≤0.008P,9.5~10.5Ni,6.6~7.4Co,1.8~2.2Mo,1.1~1.5W,0.7~1.3Cr，0.04~0.16V）由5.8t真空感应炉+2.2t真空自耗炉熔炼并锻成Ф170mm棒材。锻材1/2R切取的Ф5mm试样经1075℃90min空冷和1060℃75min油冷固溶处理+在-73℃120min深冷处理+400~600℃300min空冷时效处理。采用光学和扫描电子显微镜等分析研究了时效温度对二次硬化超高强度钢M54的力学性能及组织的影响。结果表明,试验M54钢在520℃300min时效后具有优异的综合力学性能,抗拉强度2040MPa、冲击功62J、断裂韧性110MPa·m^1/2;在560℃时效时,出现了沿晶断裂形貌,该钢冲击功K_U2和断裂韧性K_IC分别降至26J和80.6 MPa·m^1/2,随着时效温度升高至600℃时试验钢的冲击功K_U2和断裂韧性K_IC分别增加到56J和131MPa·m^1/2。 

关键词: 超高强度钢M54, 时效温度, 二次硬化, 力学性能, 复合夹杂物