2023/01/03 by TWK Kwok, Kwok, TWK, F. F. Worsnop +5
Engineering · Materials Science · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Metallurgy and Material Forming #Microstructure and Mechanical Properties of Steels #Microstructure and mechanical properties
paper · pdf · doi:10.48550/arxiv.2301.01190
openalex publication_date 2023/01/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Carbon is a well known austenite stabiliser and can be used to alter the stacking fault energy and stability against martensitic transformation in medium Mn steels, producing a range of deformation mechanisms such as the Transformation Induced Plasticity (TRIP) or combined Twinning and Transformation Induced Plasticity (TWIP + TRIP) effects. However, the effect of C beyond quasi-static tensile behaviour is less well known. Therefore, two medium Mn steels with 0.2 wt% and 0.5 wt% C were designed to produce similar austenite fractions and stability and therefore tensile behaviour. These were processed to form lamellar and mixed equiaxed + lamellar microstructures. The low C steel had a corrected Charpy impact energy (KV\textsubscript10) of 320 J cm\textsuperscript-2 compared to 66 J cm\textsuperscript-2 in the high C steel despite both having a ductility of over 35%. Interface segregation, e.g. of tramp elements, was investigated as a potential cause and none was found. Only a small amount of Mn rejection from partitioning was observed at the interface. The fracture surfaces were investigated and the TRIP effect was found to occur more readily in the Low C Charpy specimen. Therefore it is concluded that the use of C to promote TWIP+TRIP behaviour should be avoided in alloy design but the Charpy impact performance can be understood purely in terms of C in solution.