Ultrafine microstructures developed during torsional testing of Hadfield manganese steels

Abstract

AbstractThree Hadfield manganese steels were investigated containing 1·15, 1·40, and 1·70 wt-%C, all with about 13 wt-%Mn. The as processed steels consisted of austenite grains, 10–12 μm in size, with a dispersion of carbides. The steels were deformed at temperatures in the range 500–950°C in three different phase regions, namely, three phase (austenite + carbide + ferrite), two phase (austenite + carbide), and single phase (austenite). Ultrafine microstructures were developed during large strain torsional deformation. The large torsional deformation in the two phase region resulted in grain refinement through dynamic recrystallisation with the austenite grains pinned by carbide particles, minimising grain growth. Strain assisted transformation followed by spheroidisation of carbides was obtained on testing in the three phase region. The concurrent deformation and transformation resulted in ultrafine microstructures of submicrometre size constituents. Torsional properties were evaluated and related to the...