Effect of alloying and microstructure on formability of advanced high-strength steels processed via quenching and partitioning

The article focuses on the effect of alloying and microstructure formability advanced high strength steels (AHSSs) processed via quenching partitioning (Q&P). Three different Q&P with combination elements volume fraction retained austenite are subjected to uniaxial tensile Nakajima testing. Tensile mechanical properties determined, forming limit diagrams (FLDs) plotted. Microstructure tested samples is analyzed, dramatic reduction detected. It demonstrated that all able accumulate much higher amount plastic strain when using method. observed phenomenon related multiaxial stress state gradients through sheet thickness resulting in a fast transformation austenite, as well ability tempered martensitic matrix strain. Surprisingly, steel highest ductility shows lowest among studied grades. latter observation sum fractions initial fresh martensite stress/strain induced promoting formation microcracks. Their role deformation during discussed.