Test alloy steels 27Mn-3Si-3Al and  15Mn-2Si-3Al were melted by vacuum induction furnace

cast tot  to  16.5 kg  ingot

heated  to  1200  ℃  and  forged  to  φ25  mm  bar. The  27Mn-3Si-3Al  alloy  steel  maintained  single-phase  austenite structure  before  and  after  strain of which  the  stress-strain  curve  was  smooth  without  apparent  yielding  phenomenon  and work hardening peak

the tensile  strength of the  steel  solid-solution treated at  1000 C for 2 h was 692 MPa with elongation 59%.As  the  Mn  content  in  the  steel  decreased  to   15%

there  was  considerable  martensite  in  structure

and  strain  led  to large  amount  austenite  in  steel  15Mn-2Si-3Al  transferring  to  α'-M  phase

stress-strain  curve  producing  obvious  work  hardening peak  and  elongation  of steel  decreasing to  35%.