铝合金压铸件尺寸失稳问题是一个普遍存在的问题,对高精度要求的构件尤其重要。本文主要研究失稳的机理。通过高温时效或分级时效消除压铸激冷中残留的热应力,并使合金中存在的过渡相完全转变成平衡组织状态,从而达到残余应力低、组织稳定及尺寸稳定的目的。通过金相组织的观察、点阵常数千Ⅱ电阻率的测定以及相应组织状态的应力测量结果表明,原时效制度下合金组织未达到平稳状态及应力分布不均匀是造成压铸件尺寸失稳的原因。采用本研究的时效制度能降低应力水平和不均匀分布,并稳定组织,可完全消除尺寸失稳现象。同时本研究的时效制度具有节能省时的实际意义。 Aluminum die-casting dimensional instability problem is a ubiquitous problem, high-precision components required is particularly important. This paper mainly studies the mechanism of instability. The residual thermal stress in the die-casting chilling is eliminated by the aging at high temperature or the classification aging, and the transition phase existing in the alloy is completely transformed into a balanced tissue state so as to achieve the purpose of low residual stress, stable organization and dimensional stability. Through the observation of the microstructure, the resistivity of the lattice constant 1000 and the stress measurement results of the corresponding microstructures show that the alloy under the original aging regime does not reach the steady state and the stress distribution is not uniform, which results in the instability of the size of the die-casting the reason. Using the aging system of this study can reduce the stress level and uneven distribution, and stabilize the organization, can completely eliminate the size of the phenomenon of instability. At the same time, the aging system of this study has the practical significance of saving energy and saving time.