Analysis of Quenching Parameters in AISI 4340 Steel by Using Design of Experiments

This paper aims to investigate the effects of quenching parameters (temperature and time of austenitizing and cooling rate) on the microstructure, hardness and distortion of AISI 4340 steel by Design of Experiments (DoE). The factorial design was used to determine the influence of the factors on the response variable. After quench samples were characterized by optical and scanning electron microscopy, hardness test and dimensional analysis. Navy C-rings samples are used to determine the distortions after quenching due to development of residual stresses caused by non-uniform cooling. Results show that the cooling rate has a significant effect on the steel after quenching, however, the suitability of all factors is important to achieve the desired properties.

本研究旨在通过实验设计（Design of Experiments, DoE）探究淬火工艺参数（奥氏体化温度、奥氏体化时间及冷却速率）对AISI 4340钢显微组织、硬度与变形量的影响。本研究采用析因设计以明确各工艺因素对响应变量的影响机制。淬火试样通过光学显微镜、扫描电子显微镜、硬度试验及尺寸分析完成表征。针对淬火过程中因冷却不均产生残余应力所引发的变形，本研究采用海军C形环试样（Navy C-rings samples）开展变形量测定。研究结果表明，冷却速率对淬火后的钢材具有显著影响，但所有工艺参数的合理适配对于获得预期性能均不可或缺。