控制微观组织和材料损伤的锻造工艺多目标优化

Multi-Objective Optimization of Forging Process to Control the Microstructure and Damage of Material

为了对大型锻件多步锻造过程中微观组织和裂纹进行控制,提出了一种基于数值模拟的多目标优化设计方法.该方法以始锻温度、锻模击打速度和工步压下量为优化设计变量,以锻件晶粒均匀细小和材料损伤为子目标并构造总目标函数,将正交试验设计引入优化解搜索过程,获得了最优锻造工艺参数.应用该方法对圆柱体两步镦粗工艺进行多目标优化设计,并与单目标优化进行了对比分析.结果表明:工步压下量对锻件微观组织和开裂率影响最大,其次为锻模击打速度,始锻温度影响最小;要想获得均匀细小的锻后晶粒组织并防止裂纹产生,宜选用较高的始锻温度和较大的初锻压下量;多目标优化对微观组织和材料损伤的优化效果较显著.

In order to control the microstructure and fracture of heavy forgings, a multi-objective optimization method based on numerical simulation was proposed. The temperature, speed of die and height of compression in each step were taken as design variables, the microstructure of final forging and damage of material were considered into the multi-objective function. With the help of orthogonal design of experiment, optimal forging process parameters were acquired. Applying this method to two-step upsetting cylinder process optimization and comparing it with single-objective optimization, the results show that the height of compression in each step influences the function most, then it is the speed of die, and the forging temperature influences the function least. To get fine grain size distribution and prevent fracture of forging, high temperature and big first compression should be chosen. Microstructure and damage are optimized synchronously.