短流程等温淬火初始温度对组织及性能的影响

Effect of initial temperature of short-process austempering on microstructure and properties

为了研究短流程等温淬火的初始温度对铸件组织和性能的影响,采用消失模铸造工艺制备铸件.当铸件分别冷却到1 173和1 223 K初始温度时,放入50%KNO3+50%NaNO2淬火介质进行等温处理,然后空冷至室温.结果表明,铸件中出现了珠光体,ADI-1223和ADI-1173的硬度分别为381和366 HV.当载荷为10 N时,ADI-1223的摩擦系数为0. 289,磨损体积为71. 3×10^-5 mm^3;ADI-1173的摩擦系数为0. 273,磨损体积为83. 7×10^-5 mm^3.当载荷为12 N时,ADI-1223的摩擦系数为0. 242,磨损体积为114. 1×10^-5 mm^3;ADI-1173的摩擦系数为0. 213,磨损体积为136. 5×10^-5 mm^3.因此,ADI-1223的硬度高于ADI-1173,摩擦系数大于ADI-1173,磨损量小于ADI-1173.

In order to study the effect of initial temperature of short-process austempering on the microstructure and properties of castings,the castings were prepared using lost foam casting technology. When the castings were cooled to the initial temperature of 1 173 and 1 223 K,the quenching medium of 50%KNO3 +50%NaNO2 was adopted to perform isothermal treatment,and then the castings were cooled down to room temperature in the air. The results show that the pearlite appears in the castings,and the hardness of ADI-1223 and ADI-1173 are 381 and 366 HV,respectively. When the load is 10 N,the friction coefficient of ADI-1223 is 0. 289,and the wear volume of it is 71. 3 × 10^-5 mm^3;the friction coefficient of ADI-1173 is 0. 273,and the wear volume of it is 83. 7 × 10^-5 mm^3. When the load is 12 N,the friction coefficient of ADI-1223 is 0. 242,and the wear volume of it is 114. 1 × 10^-5 mm^3;the friction coefficient of ADI-1173 is 0. 213,and the wear volume of it is 136. 5 × 10^-5 mm^3. Therefore,the hardness of ADI-1223 is higher than that of ADI-1173,the friction coefficient of ADI-1223 is greater than that of ADI-1173,whereas the wear amount of ADI-1223 is lower than that of ADI-1173.