5Cr2NiMoVSi模具钢的相变规律与力学性能

采用Formastor-FⅡ全自动热膨胀相变仪测试了5Cr2NiMoVSi模具钢在不同冷却速度下的膨胀曲线,结合显微组织和硬度分析结果,绘制连续冷却转变(CCT)曲线,研究了材料的相变特性;通过热处理工艺试验研究了回火参数对材料力学性能的影响。结果表明,5Cr2NiMoVSi钢的过冷奥氏体具有较好的稳定性,连续冷却转变曲线大幅度右移;材料硬度和冷却速度关联较大,随着冷却速度增大,硬度迅速提高;临界冷却速度为0.4 ℃/s,马氏体硬度基本保持在640 HV以上;材料回火温度在550~590 ℃时,可获得不低于1628 MPa的抗拉强度,具有较好的回火稳定性。

Phase transformation and mechanical properties of 5Cr2NiMoVSi die steel

Thermal expansion curves of 5Cr2NiMoVSi die steel under different cooling conditions was measured by means of Formastor-FⅡ full automatic transformation measuring apparatus. Combining microstructure and hardness results, the phase transformation characteristics of the 5Cr2NiMoVSi die steel was analyzed and the continuous cooling transformation curves were gained. The effect of tempering parameter on mechanical properties of the steel was studied. The results show that the supercooled austenite of 5Cr2NiMoVSi steel has good stability, and the continuous cooling transformation curve shifts to the right greatly. The hardness of materials has a great correlation with the cooling rate, and the hardness increases rapidly with the increase of cooling rate. The critical cooling rate of the steel is 0.4 ℃/s,and the martensitic hardness is basically maintained above 640 HV. When tempered between 550 ℃ and 590 ℃, the tensile strength of the material is not less than 1628 MPa, indicating good tempering stability.