QUENCHING AND PARTITIONING HEAT TREATMENT OF DP590 STEEL
Abstract - Dual-phase automotive steels have an excellent balance of ductility, high tensile strengths, easy cold formability, and very good crash energy absorption. A low yield-to-tensile-strength ratio creates high global formability for deep-drawing and high-stretching capacities in dual-phasesteel. Basic research on advanced high-strength steels is challenged by an increasing and urgent demand for designing and synthesizing high-strength alloys that enable the manufacturing of highly fuel-efficient vehicles. Quenching and Partitioning (Q&P) steels yield an excellent balance of high tensile strength and good.
Thepresent research work aims to study dual-phase(DP590) steel and evaluate its microstructural and mechanical properties after quenching, and partitioning process. The samples were heated to austenization temperatures of 950℃ and 825℃ with varying partitioning temperature levels of 350, 400, and 450℃. Thereafter the samples were quenched to room temperature. Further, partitioning time (1 min, 15 min, and 30 min) was varied for a partitioning temperature of 350℃. The amount of retained austenite present varies with varying partitioning temperatures. The characterization techniques such as optical microscopy, scanning electron microscopy, Vickers microhardness test, X-ray diffraction, corrosion (immersion & electrochemical) test, and tensile test have been performed to evaluate properties. The properties obtained after heat treatment have also been compared with DP590 steel properties in its as-received form. The corrosion rate increases with exposure time to the corrosive environment, here 3.5 wt% NaCl solution. The temperature (both austenization and partitioning) and time are optimized to obtain the required strength and ductility. The yield strength and ultimate tensile strength increase with increasing partitioning temperature due to increased volume fraction of retained austenite with temperature.
Keywords - Dual-Phase Steel, Quenching &Partitioning, Corrosion, DP Steel