大型7085铝合金筒形件淬火残余应力及其消减工艺研究

Research on quenching residual stress and residual stress reduction process of large-scale 7085 aluminum alloy cylindrical parts

以大型7085铝合金筒形件为研究对象,研究了在最大程度保证铝合金大锻件性能的同时尽可能减小其淬火残余应力的方法。基于Abaqus平台,分别建立了大型筒形件淬火有限元模型和淬火后冷胀形有限元模型,考虑了淬火工艺和冷胀形工艺间的数据继承关系,分析了工艺参数对锻件性能及残余应力的影响规律。针对大型7085铝合金筒形件的淬火过程,将7085铝合金的等温转变曲线和时间-温度-性能曲线写入Abaqus用户子程序USDFLD中,计算了大型筒形件在不同淬火工艺条件下的析出相含量和分布、对应的硬度变化以及残余应力分布,获得了35℃的淬火水温是最优的选择。在消减淬火残余应力的冷胀形工艺中,基于不同的淬火水温条件开展了胀形量、胀形道次和每道次之间环转动角度的正交模拟实验,结果显示胀形量对残余应力消减的影响最显著,胀形量为4.5%时大型7085铝合金筒形件的应变均匀性最好且残余应力消减最充分。将仿真获得的优化淬火工艺和胀形方案应用于生产试制,所获得的大型筒形件各项力学性能达到设计要求,其残余应力实测结果与仿真结果对比具有较好的一致性。

Taking large-scale 7085 aluminum alloy cylindrical parts as the research object,the method of ensuring the performance of large-scale aluminum alloy forgings to the maximum extent and reducing the residual quenching stress as much as possible was studied.Finite element models for quenching and subsequent cold expansion were established based on the Abaqus platform,considering the data inheritance relationship between the quenching and cold expansion processes.The effect laws influence of process parameters on performance of forgings and residual stress were analyzed.For the quenching process of large-scale 7085 aluminum alloy cylindrical parts,the time-temperature-transformation(TTT)curve and time-temperature-property(TTP)curve of 7085 aluminum alloy were integrated into the Abaqus user subroutine USDFLD,and the precipitation phase content and distribution,corresponding hardness changes and residual stress distribution under different quenching conditions were calculated.A quenching water temperature of 35℃was determined as the optimal choice.In the cold expansion process for reducing residual quenching stress,orthogonal simulation experiments were conducted under different quenching water temperature conditions regarding expansion amount,expansion pass and rotation angle between each pass.The results show that the expansion amount has the most significant effect on reducing residual stress,with an expansion amount of 4.5%resulting in the best strain uniformity and most thorough reduction of residual stress for large-scale 7085 aluminum alloy cylindrical parts.The optimized quenching process and expansion scheme obtained through simulation were applied to production trials,and the mechanical properties of the large-scale cylindrical parts meet the design requirements. The measured results of residual stresses show good consistencywith the simulation results.