【摘要】 以热锻模具为应用对象,采用光镜、扫描电镜、电子拉伸试验机、冲击试验机及硬度计等,研究了RE复合添加剂对铸造热锻模具钢基体组织、力学性能、热疲劳性能的影响,并在此基础上,采用真空实型铸造近净成形技术试制了凸轮轴模具。结果表明,经RE复合添加剂处理后的铸造热锻模具钢,其基体组织更加均匀,晶粒细化明显,力学性能显著改善,热疲劳裂纹萌生和扩展得到有效抑制。与未加入RE复合添加剂处理的热锻模具钢相比,RE复合添加剂处理的热锻模具钢在基体硬度保持不变的情况下,冲击韧性提高1.15倍,达到了67.9 J/cm~2;常温抗拉强度和高温抗拉强度(600℃)分别提高了200 MPa以上,达到1457 MPa和1108 MPa;热疲劳性能明显改善。采用该模具钢试制的凸轮轴热锻模具,在2500吨压力机上锻造凸轮轴15648件,模具使用寿命比相同工作条件下5CrNiMo模具提高2倍以上,加工成本降低约25%。更多还原

【Abstract】 The application object is hot fogring dies, the effect of RE compound additive on the microstructure, mechanical and thermal fatigue properties of the casting hot forging die steel were investigated by OM, SEM, electron-tensile tester,impact testing machine and hardness tester etc. On that basis, a hot forging die camshaft was manufactured by vacuum fullmold casting(V-EPC) near net forming technique. The results showed that the matrix microstructure was more uniform, grain was refined obviously, mechanical properties were improved significantly, and the initiation and growth of thermal fatigue crack were effectively inhibited for the hot working die steel by RE compound additive modifying. Compared with the casting hot forging die steel without adding RE compound additive, the impact toughness was increased by 1. 15 times and reached 67. 9 J/cm~2, the ultimate tensile strength(UTS) were respectively increased by more than 200 MPa at both room and high temperature(600 ℃) and reached 1457 MPa and 1108 MPa, thermal fatigue property was obviously improved, and with same hardness for the hot forging die steel adding RE compound additive. The camshaft die made from the hot forging die steel forged the engine camshafts up to 15648 pieces at 2500 tons crank press. Compared with 5CrNiMo hot forging die under the same forging conditions, the service life of the test die was increased by more than 2 times, and the processing cost could be reduced by about 25%.更多还原