High‐Temperature Properties of High Mn Steel with Al, Si, and C

High‐manganese steels containing 10 to 30 wt.‐% (weight‐%) Mn exhibit high strength and ductility. This study aims to improve the understanding of mechanisms determining the high‐temperature properties of such steels. A shear test equipment is developed, enabling mechanical testing in an as‐cast state after solidification from melt. This study covers four steel grades of about 13, 15, 17, and 21 wt.‐% Mn, 0.07 up to 0.8 wt.‐% C, and about 2.5 wt.‐% Al and Si each. The results are for 1000 °C and both for as‐cast and annealed states. Annealing is done for 1 h at 1020 °C, corresponding to a testing temperature of 1000 °C. For a better understanding of the material properties, micro‐segregation is investigated. Two types of micro‐segregation are found, type 1 resulting from solidification and type 2 from phase transformation from ferrite to austenite. Type 1 segregation is large, especially for Si and intermediate C‐contents. Type 2 segregation found for lower C‐ and Mn‐contents and predominately in the as‐cast state is associated with an increased ferrite content resulting in embrittlement. Increasing embrittlement is also found at elevated C‐contents mainly due to primary carbide formation. Annealing reduces micro‐segregation and the amount of ferrite and carbide precipitation.