Effect of Q&P Treatment on Microstructure and Mechanical Properties of High Strength Hot Stamped Steel

Q&P treatment is adopted to address the problems of high strength and low plasticity of high-strength steel after quenching treatment, reducing some strength and significantly increasing elongation, thereby improving the strength plasticity product. The results show that the raw material structure consists of ferrite and pearlite, and after partitioning, the structure transforms into martensite and residual austenite. When the partitioning temperature is constant, the strength of high-strength steel increases with the increase of partitioning time, but the elongation will decrease with the increase of partitioning time. When the partitioning time is constant, the strength of high-strength steel decreases with the increase of partitioning temperature, but the elongation increases with the increase of partitioning temperature. At a partitioning temperature of 260 ℃ and a partitioning time of 12 s, the strength plastic product of the material is 17.20 GPa·%, reaching its maximum strength plastic product. The microstructure of the quenched sample is basically full martensite, and after the microstructure transformation, the material strength is greatly improved but the elongation is too low; Q&P sample makes carbon desorb and dissolve from supersaturated lath martensite to austenite, increasing the stability of residual austenite in the matrix to room temperature, thus increasing the content of residual austenite in the material, which can reduce part of the strength, greatly increase the elongation, and thus improve the strength plastic product.