7050铝合金环件形变热处理残余应力多尺度分析

Multi-scale Analysis of Residual Stress in Thermomechanical Treatment Process of 7050 Aluminum Alloy Ring

摘要:

铝合金环件在制备与加工过程中产生宏观残余应力的同时也会产生微观残余应力。宏观残余应力的释放和重新分布会引起工件在加工和服役过程中变形，影响其尺寸精度，与外力叠加后使工件强度降低，降低工件疲劳极限。微观残余应力与外力的联合作用下，易造成微区应力集中，使工件在远小于屈服应力下局部产生微裂纹并导致断裂。影响铝合金锻件中残余应力最主要的工序是固溶处理后的淬火过程。本文采用盲孔法检测了7050铝合金环件固溶-冷胀形过程中的宏观残余应力，并利用ABAQUS软件对7050铝合金环件固溶-冷胀形过程进行了宏观有限元仿真模拟，系统分析了7050铝合金环件在固溶-冷胀形过程中的宏观残余应力演化规律，得出在固溶淬火之后引入合适的冷胀形工艺可以大幅消减7050铝合金宏观残余应力。通过多尺度仿真方法的联合应用实现了残余应力的跨尺度分析：基于晶体塑性有限元模拟方法，根据宏观有限元模拟结果确定感兴趣微区，提取该微区的应变历史，利用ABAQUS软件将应变历史施加至对应位置的微观多晶模型上，研究微观残余应力分布规律及其与微观组织的关系。

Abstract:

In the process of preparing and processing aluminum alloy rings, micro residual stress is generated, while macro residual stress is also generated. The release and redistribution of macro residual stress cause the deformation of the workpiece during processing and service, which will affect its dimensional accuracy. The superposition of macro residual stress and external force reduces the strength and fatigue limit of the workpiece. Under the combined action of micro-residual stress and external force, it is easy to cause stress concentration in the micro-area, so that the workpiece produces micro-cracks under far less than the yield stress, and ultimately fractures. The most important process affecting the residual stress in aluminum alloy forgings is the quenching process after solution treatment. In this paper, the macro residual stress of 7050 aluminum alloy ring during solution-cold bulging process was detected by blind hole method, and the macro finite element simulation of 7050 aluminum alloy ring during solution-cold bulging process was carried out by ABAQUS software. The macro residual stress evolution law of 7050 aluminum alloy ring during solution-cold bulging process was analyzed. It is concluded that the introduction of appropriate cold bulging process after solution quenching can greatly reduce the macro residual stress of 7050 aluminum alloy. The cross-scale analysis of residual stress is realized by the combined application of multi-scale simulation methods: Based on the crystal plastic finite element simulation method, the micro-area of interest is determined according to the macro-finite element simulation results, and the strain history of the micro-area is extracted. The strain history is applied to the micro-polycrystal model at the corresponding position by ABAQUS software to study the distribution law of micro-residual stress and its relationship with the microstructure.