Tailoring the Properties of 17-4 PH Steel via Cryogenic Treatment
摘要
This work systematically investigates the effects of cryogenic treatment at varying temperatures (− 20, − 60, and − 196 °C) on the microstructure and mechanical properties of 17-4 PH steels. The quantitative results reveal that a decrease in treatment temperature induces significant microstructural evolution. The average martensitic lath size in the untreated sample is 227.19 nm, which is effectively refined to 100.88 nm after cryogenic treatment at − 196 °C. Meanwhile, the cryogenic treatment promotes the precipitation of fine carbides. These microstructural evolutions contributed to a substantial enhancement in the mechanical properties. Compared with the untreated sample, the − 196 °C cryogenically treated specimen exhibits a 3.6% increase in hardness (from 356 to 369 HBW), a remarkable 48.8% improvement in impact toughness (from 38.7 to 57.6 J), and a 30.4% reduction in wear rate (from 5.59 × 10−8 to 3.89 × 10−8 mm3/N mm). The synergistic strengthening effect of refined martensite and dense fine carbides achieves an optimized balance of strength, toughness, and wear resistance. These findings highlight the significant potential of − 196 °C cryogenic treatment in enhancing the overall performance of 17-4 PH steel, providing a crucial theoretical basis and practical guidance for high-performance applications such as aerospace fasteners.