采用OM、SEM、TEM和硬度测试等手段,研究了不同回火温度对3Cr2MnNiMoV预硬型塑料模具钢组织和力学性能的影响.结果表明:在380～640℃回火,随回火温度升高,试验钢的回火硬度、抗拉强度和屈服强度,总体呈相同的下降趋势,而冲击功和断面收缩率显著增加;经560℃回火后,试验钢具有最佳的综合力学性能:硬度44 HRC,冲击功65 J,抗拉强度1450 MPa,屈服强度1300 MPa,断面收缩率61％;在380℃回火时,钢的基体组织析出了不规则短杆状渗碳体导致室温冲击韧性较低.随温度升高,渗碳体形貌由短杆状变为细小颗粒状且分布均匀使室温冲击韧性不断提高.
Effects of tempering temperature on microstructure and mechanical properties of pre-hardened plastic mould steel 3Cr2MnNiMoV were investigated by means of OM,SEM,TEM and hardness test.The results show that in the tempering temperature range of 380-640 ℃,the tempering hardness,tensile strength and the yield strength of the steel decrease with the increasing of tempering temperature,while the impact toughness and the plasticity increase significantly.After tempering at 560 ℃,the optimized comprehensive mechanical properties of the steel are obtained,which the hardness is 44 HRC,impact toughness is 65 J,tensile strength is 1450 MPa,yield strength is 1300 MPa,percentage reduction of area is 61％.Additionally,irregular short rods cementite is observed in the steel after tempering at 380 ℃,which resulted in lower impact toughness at room temperature.With the increasing of tempering temperature,the morphology of cementite changes from short rod to fine particles and uniform distribution,which resulted in higher impact toughness.
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