Method and apparatus for treating a steel article

摘要

A method for forming and treating a steel article of a high strength and high ductility alloy particularly suited for use as armor plate. The method includes the steps of providing a starting material for the steel article, heating the starting material to a peak temperature range in less than ten seconds, holding the heated steel composition at the peak temperature range for between two and six seconds, quenching the heated steel composition from the peak temperature range to below 100° C. (212° F.) at a temperature rate reduction of 400 and 3000° C./sec (752 and 5432° F./sec), removing residual quench media from the surface of the quenched steel composition, tempering the quenched steel composition at a temperature of 100 to 260° C. (212 to 500° F.); and air cooling the tempered steel composition to less than 100° C. (212° F.) to form a steel having desired mechanical properties.

主权项

1. A method for treating a steel article to form a high yield strength and ductile alloy comprising the steps of:
(a) providing a steel composition having a material thickness less than 0.5 inches (12.7 mm), having an initial microstructure of ferrite and pearlite, and having a composition of, by weight, carbon between 0.25 and 0.55% silicon between 0.15 and 0.35%, manganese between 0.40 and 1.0%, chromium between 0.80 and 1.10%, molybdenum between 0.15 and 0.25%, sulfur less than 0.040%, phosphorus less than 0.035%, balance with iron and incidental ingredients; (b) heating the provided steel composition to a peak temperature of between 850° C. (1562° F.) and 1150° C. (2102° F.) in less than ten seconds; (c) holding the heated steel composition at the peak temperature range for between two and ten seconds; (d) quenching the heated steel composition from the peak temperature range to below 100° C. (212° F.) at a temperature rate reduction of between 400 and 3000° C./sec (752-5432° F./sec); (e) removing residual quench media from the surface of the quenched steel composition; (f) tempering the quenched steel composition at a temperature from 100° C. to 260° C. (212-500° F.) for less than ninety minutes; (g) air cooling the tempered steel composition to less than 100° C. (212° F.) to form a steel article having at least 80% martensite and up to 5% bainite by volume, a yield strength of at least 1800 MPa, a total elongation between 5% and 12%, and having a V50 protection ballistic limit at 30° obliquity angle between 2300 and 2510 feet per second (701-765 m/s) with a .30 caliber armor piercing round for a thickness of 0.25 inches (6.35 mm).