精密铸造件产品回火的目的有以下几个方面：
The tempering purpose of precision casting products includes the following aspects:
1、降低脆性，消除或减少内应力，精密铸件淬火后存在很大内应力和脆性，如不及时回火往往会使精密铸件发生变形甚至开裂。
1. Reduce brittleness and eliminate or reduce internal stress. There is great internal stress and brittleness in precision castings after quenching. If not tempered in time, the precision castings will often be deformed or even cracked.
2、获得工件所要求的机械性能，工件经淬火后硬度高而脆性大，为了满足各种工件的不同性能的要求，可以通过适当回火的配合来调整硬度，减小脆性，得到所需要的韧性，塑性。
2. Obtain the mechanical properties required by the workpiece. After quenching, the workpiece has high hardness and high brittleness. In order to meet the requirements of different properties of various workpieces, the hardness can be adjusted through appropriate tempering to reduce brittleness and obtain the required toughness and plasticity.
3、稳定工件尺寸
3. Stable workpiece size
4、对于退火难以软化的某些合金钢，在淬火(或正火)后常采用高温回火，使钢中碳化物适当聚集，将硬度降低，以利切削加工。
4. For some alloy steels that are difficult to soften after annealing, high temperature tempering is often used after quenching (or normalizing), so as to properly aggregate carbides in the steel and reduce the hardness, so as to facilitate cutting.