Conventional austempering of steel strips with 0.4% C and
1.4% Mn resulted in a predominantly bainitic microstructure Modified austempering of similar strips led to three different types of microstructures depending on the austenitising
temperature.
1: Alternate thick bands of ferrite and pearlite. Such
type of microstructure was formed when strip austenitising temperature varied between 750 and 800 ◦C.
Non-uniform blocky ferrite and pearlite were
formed when the austenitising temperature was between
830 and 850 ◦C. The volume fraction of ferrite varied
between 18 and 30%.
2.Non-uniform blocky ferrite and pearlite were
formed when the austenitising temperature was between
830 and 850 ◦C. The volume fraction of ferrite varied
between 18 and 30%.
3. Evaluation of tensile properties showed that type III
microstructure resulted in the best combination of tensile
properties, i.e. tensile strength of 95 kg/mm2 and elongation of 9%. It was also found that microstructure comprising
uniformly distributed ferrite and pearlite gave higher ten sile strength than those achieved in the microstructure with
banded ferrite and pearlite.