Experimental and theoretical analysis of multiphase microstructure in a newly designed MnSiCrC quenched and partitioned steel to promote bainitic transformation: The significant impact on mechanical properties

Fundamentals and application of solid-state phase transformations for advanced high strength steels containing metastable retained austenite

“…Besides the migration of martensite/ austenite interface, bainite formation was also found to occur during the partitioning process [163,257,258]. The purpose of the Q&P process is to stabilize austenite down to ambient temperatures via carbon partitioning from the martensite into the austenite.…”

“…However, it is unavoidable that austenite containing an insufficient percentage of carbon content would decompose into bainite during partitioning. The formation of bainitic ferrite can divide the unstable blocky austenite into film-like austenite [258][259][260][261], and also contribute to carbon enrichment in its surrounding austenite. Bainite formation in Q&P steels was also found to benefit the ductility and toughness [112,113,192,258].…”

Effect of Step Quenching Heat Treatments on the Kinetics of Ferrite Formation and Quenching & Partitioning Modeling for a Commercial C-Mn-Si Steel

“…Chen et al 44 , studying a 0.2C-2.82Mn-1.58Si steel, showed that the occurrence of bainitic transformation in the Q&P process leads to a greater retained austenite fraction due to the optimization of carbon redistribution (which increase the austenite stability) in addition to carbon partition during the transformation 45 . This lead to a significant improvement in uniform and total elongation combined with a high strength, with which other authors also agree [46][47][48][49] . Li et al 25 , as already mentioned, proposed the CCET model precisely based on the bainitic transformation occurrence in C-Mn-Si steels submitted to Q&P processes, with partitioning temperatures between 350°C and 450°C.…”

The Significance of Mn Prepartitioning on Bainitic Transformation and Mechanical Properties of a Low‐Carbon Bainitic Steel

“…[ 5,39 ] The proceeding of bainitic transformation is accompanied with C partitioning from BF instead enriches the surrounding untransformed austenite, and thereby stabilizing it down to ambient temperature. [ 3 ] The Mn‐depleted and Mn‐enriched regions as a result of Mn‐PrPT are still remained after austenitizing due to the slow diffusion coefficient of Mn in austenite. Hence, bainitic transformation first occurs in Mn‐depleted austenite region, and the surrounding untransformed Mn‐enriched austenite tends to stabilize due to the enrichment of C, which in turn reduces the total amount of bainite.…”

“…Bainitic steels are used as high‐performance structural material for automotive, bearing, gear, aerospace, construction industries, and railway systems (including rails and crossings) because of their high strength, good ductility and toughness. [ 1–4 ] Among them, high‐carbon silicon‐rich bainitic steels known as advanced high strength steels have been developed, which on austempering at low temperature (between martensite start [ M S ] and bainite start [ B S ] temperatures) result in low‐temperature bainitic microstructure. [ 5,6 ] However, in recent years, some researchers have attempted to transfer the low‐temperature bainite concept to low‐carbon steels.…”