Development of cast high strength microalloyed steels

Abstract

Cast microalloyed steels containing 1.25–1.3%Si and > 2.0%Mn plus small quantities of nickel, chromium and microalloying elements (Nb, V, Ti) may be adequately strengthened by air cooling from 950°C. After a tempering treatment at 500–550°C, these low carbon (0.15–0.20%C) cast steels can exhibit YS 520– 725 MPa, UTS 690–820 MPa, 20–40% El and impact toughness up to 30 J at -40°C. The air cooled microstructures in these steels consist of precipitation strengthened ferrite + bainite. The tempering treatment induces transformation of retained austenite to pearlite and improves mechanical properties.

Keywords:

• HIGH STRENGTH STEELS
• MICROALLOYED STEELS
• HEAT TREATMENT
• TEMPERING