Impact of Quenching Temperatures on Microstructure and Properties of Low alloy DIN ۱.۵۰۲۵ Steel During Two-step Q&P Heat treatment

This study investigates the microstructural evolution and mechanical properties of DIN ۱.۵۰۲۵ steel subjected to two-step quenching and partitioning (Q&P) heat treatments. Critical Q&P parameters, including initial quenching temperatures (۱۴۰ °C and ۱۸۰ °C) and partitioning at ۲۴۵ °C for ۱۰۰۰ seconds, were systematically explored. The results reveal that quenching at lower temperatures leads to a higher fraction of martensite and reduced retained austenite, while higher quenching temperatures promote earlier bainite transformation during partitioning due to increased retained austenite stability. Microstructural analysis using laser microscopy and EBSD demonstrated the interplay between martensite, bainite, and retained austenite phases, highlighting the influence of thermal history on phase stability and morphology. Mechanical testing indicated that samples quenched at ۱۴۰ °C achieved higher hardness (۶۱۹.۲±۱۰ HV۳۰kg) compared to those quenched at ۱۸۰ °C (۵۸۶.۶±۷ HV۳۰kg), corroborating the microstructural findings. This research underscores the potential of optimizing Q&P parameters to tailor the microstructure and properties of advanced high-strength steels for industrial applications.

کلیدواژه ها:

Advanced high-strength steel (AHSS) ، Quenching and partitioning (Q&P) ، Retained austenite (RA) ، Carbon partitioning ، Bainite transformation