EFFECTS OF CARBON CONTENT ON MECHANICAL-PROPERTIES OF 5-PERCENT-MN STEELS EXHIBITING TRANSFORMATION-INDUCED PLASTICITY

A series of highly ductile, high strength steels exhibiting transforma tion induced plasticity due to retained austenite was developed by var ying the carbon content in the range 0.001-0.4 wt-% in 5 wt-%Mn based steel. For up to 0.1%C the mechanical properties are insensitive to co oling rate after intercritical heating, but a further increase in carb on content causes a large sensitivity to the cooling rate, owing to ca rbide precipitation occurring during slow cooling. By suppressing this carbide precipitation with water quenching after the intercritical ho lding, an excellent combination of tensile strength (1580 MN m(-2)) an d uniform elongation (21%) was attained at 0.3%C in this series.