Austenitic manganese steel, aka Hadfield’s steel, has a coefficient of thermal expansion about 1.5 times that of ferritic steels. The coefficient is about 18 &[ignore]mu[/ignore];/m/oC at room temperature and 20 &[ignore]mu[/ignore];/m/oC over the range 100-300oC. Measurement was made on a wrought sample of composition 1.22% C, 13.0% Mn alloy which had been heated to 1050oC [solutionizes carbon] and air cooled. The composition corresponds to ASTM A128 Grade B-3 [UNS J91139]. Grades A and B-4 are similar.
Hadfield’s Manganese Steel is still used extensively (with minor alloying changes as in the various ASTM A128 Grades) due to its high toughness, ductility, high work-hardening capacity and good resistance to wear. It is particularly useful for severe service that combines abrasion and heavy impact as in power shovel buckets and teeth, railway uses, rock crushing, etc.
Austenitic manganese steels are typically cast to shape (difficult to machine due to toughness and work hardening). Also, it is normally water quenched after solutionizing in order to yield finer austenite grains and precipitated carbides. It is not normally used above ~260oC longterm (or more than 1 hour at 425oC) due to carbide precipitation and austenite transformation [probably less relevant if originally air cooled]. It is considerably more ductile than ferritic steels at sub-zero temperatures, e.g., 12.3% elongation at -150oC for a 1.4%, 12% Mn steel.
– “Austenitic Manganese Steel,” pp. 568-588 in Metals Handbook, 9th Edn., vol. 3 (1980).