Print Email Facebook Twitter Thermal and mechanical stability of retained austenite surrounded by martensite with different degrees of tempering Title Thermal and mechanical stability of retained austenite surrounded by martensite with different degrees of tempering Author Hidalgo Garcia, J. (TU Delft (OLD) MSE-3) Findley, K.O. (Colorado School of Mines) Santofimia, Maria Jesus (TU Delft (OLD) MSE-3) Date 2017 Abstract The mechanical and thermal stability of austenite in multiphase advanced high strength steels are influenced by the surrounding microstructure. The mechanisms underlying and the relations between thermal and mechanical stability are still dubious due to the difficulty of isolating other factors influencing austenite stability. In this work, martensite/austenite microstructures were created with the only significant difference being the degree of tempering of the martensite matrix. Hence, the effect of tempering in martensite is isolated from other factors influencing the stability of austenite. The thermal stability during heating of retained austenite was evaluated by monitoring phase fractions as a function of controlled temperature employing both dilatometry and magnetometry measurements. The mechanical stability was studied by performing interrupted tensile tests and determining the remaining austenite fraction at different levels of strain. The thermal stability of this remaining austenite after interrupted tests was studied by subsequent reheating of strained specimens. The results are evidence for the first time that thermal recovery of martensite during reheating assists austenite decomposition through shrinkage and softening of martensite caused by a reduction of dislocation density and carbon content in solid solution. This softening of martensite also leads to a subsequent reduction of austenite mechanical stability. Additionally, remaining austenite after pre-straining at room temperature was thermally less stable than before pre-straining, demonstrating that plastic deformation has opposing effects on thermal and mechanical stability. Subject Martensite temperingQuenching and partitioning steelsRetained austeniteThermomechanical stability To reference this document use: http://resolver.tudelft.nl/uuid:2828efdb-cccb-4eba-98f6-43c9ec739c57 DOI https://doi.org/10.1016/j.msea.2017.03.017 ISSN 0921-5093 Source Materials Science and Engineering A: Structural Materials: Properties, Microstructures and Processing, 690, 337-347 Part of collection Institutional Repository Document type journal article Rights © 2017 J. Hidalgo Garcia, K.O. Findley, Maria Jesus Santofimia Files PDF 1_s2.0_S0921509317303064_main.pdf 1.86 MB Close viewer /islandora/object/uuid:2828efdb-cccb-4eba-98f6-43c9ec739c57/datastream/OBJ/view