Studies on the development of high-strength dual-phase steel sheets with high rm values

Experimental studies of cold-rolled sheets from a series of silicon-phosphorus (0.07 pct P, variable Si) steels showed that, depending on the silicon content, a dual-phase sheet can be produced with 70 ksi (483 MPa) yield strength, 100 ksi (690 MPa) tensile strength, 15 pct elongation (in one inch), and anr _mvalue of about 1.8. The relatively low elongation value is believed to be due to quench aging. Further development to increase hardenability and reduce the required cooling rates is expected to improve the ductility without reducingr _mvalues.