时效温度对Cu沉淀强化超高强海工钢力学性能的影响

Effect of Aging Temperature on Mechanical Properties of Ultra High Strength Marine Engineering Steel Strengthened by Cu Precipitation

采用Thermo-Calc软件、SEM和HRTEM等分析技术研究了时效温度对低碳超高强海工钢中Cu的析出行为及其对力学性能的影响。结果表明,400~550℃时效,由于Cu的时效沉淀析出,Ni-Cr-Mo-Cu钢的时效硬度显著高于Ni-Cr-Mo钢,最高时效峰值硬度达到386HV。525℃时效,Cu粒子具有较低的粗化速率,Cu粒子析出的平均半径为5.2 nm,强化机制为切过机制,产生的强化增量约为100 MPa。时效温度升高至550~575℃,Cu粒子粗化,强化机制转变为绕过机制,强化增量小于50 MPa。Ni-Cr-Mo-Cu钢525℃时效可以获得良好的强韧性,屈服强度达到1120 MPa,-80℃低温V型冲击功为76 J,与Ni-Cr-Mo钢相比,添加Cu使其屈服强度、-80℃冲击功分别提高9%和15%。

Effect of aging temperature on copper-precipitation behavior and mechanical properties of low carbon ultra-high strength marine engineering steel was investigated by means of Thermo-Calc software,SEM and HRTEM.The results showed that aging hardness of Ni-Cr-Mo-Cu steel was significantly higher than Ni-Cr-Mo steel between 400℃and 550℃aging,and the highest aging peak hardness was 386HV.Cu particles exhibited a lower coarsening rate at 525℃aging,the average precipitation radius of Cu particles was 5.2 nm,and the Cu precipitates yielded shear strengthening mechanism with a strength increment of 100 MPa.When aging temperature was 550℃to 575℃,the strengthening mechanism transformed into by-pass because of the coarsening of Cu particles,as a result,the strength increment was less than 50 MPa.The Ni-Cr-Mo-Cu steel could achieve better match of strength and toughness at 525℃aging,the yield strength reached 1120 MPa and the-80℃low-temperature V-notch impact energy was 76 J,which was 9%and 15%higher than the value obtained in Ni-Cr-Mo steel.