Mechanical properties and work hardening behaviour of spring steel after the quenching-partitioning process

Recently, to create high-strength steels with suitable ductility, quenching and partitioning (Q&P) heat treatment was employed to form a micro-composite microstructure. In the current study, the influence of different factors, such as quenching temperature (temperature range 170–230 ° C) and partitioning time (3–30 min) on the microstructure and mechanical properties, was evaluated by applying quenching and partitioning process to a spring steel of 1.7102. The findings demonstrated that excessively extending the partitioning time caused retained austenite to transform and the production of carbide precipitation in the microstructure. However, the sample that was quenched at 230°C and partitioned at 300°C for 3 min produced the optimum combination of mechanical properties, including an impact energy of 17 J, tensile strength of 1943MPa, total elongation of 12.5%, reduction area of 30%, and hardness of 56 HRC. In addition, a desirable combination of tensile properties, including the tensile strength of 1997MPa, yield strength of 1730MPa, elongation of 10.3%, and reduction area of 48%, was obtained by quenching at 170°C and partitioning at 300°C for 8 min. The evaluation of work-hardening behaviour revealed that the sample quenched at 200 °C and partitioned at 300 °C for 8 min had the best work-hardening ability.