from the conferences organized by TANGER Ltd.
In recent years, the intensive research work has been carried out on the development of heat treatment which allowed obtaining carbide-free microstructures with retained austenite. These include the quenching with isothermal annealing (austempering) leading to obtain a nanocrystalline bainite [1,2] and Quenching&Partitioning (Q&P) [3] leading to obtain a microstructure composed of carbon-depleted martensitic matrix and carbon-enriched retained austenite. These processes are suitable for steels containing alloying additions of Silicon and Aluminum that suppress formation of iron carbides [3]. In the case of Q&P process the quenching is performed at temperature (TQ) below MS in order to obtain an incomplete martensitic transformation. The stability of retained austenite is obtained by carbon partitioning from martensite to thin interlath films of untransformed austenite. Carbon partitioning process occurs during isothermal holding at partitioning temperature (TP) directly after cooling to the quenching temperature (TQ). The increased volume fraction of retained austenite may improve toughness of steel [4,5]. Moreover such steels may exhibit the TRIP effect which promotes the ductility [6,7]. Our preliminary studies showed that metastable retained austenite in microstructure may also improve wear resistance [8]. In this study an attempt to obtain microstructure composed of martensite and retained austenite in 35SrSiMn5-5-4 steel by means of Q&P process was undertaken. The parameters of Quenching and Partitioning were designed to receive about 22 % of stable austenite in 35SrSiMn5-5-4 steel at room temperature. It was shown [8] that such amount of retained austenite should improve wear resistance in comparison to the same steel subjected to conventional heat treatment consisting on quenching followed by tempering.
Keywords: Steel, quenching & partitioning, martensite/austenite mixture, wear resistance© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.