HIGH STRENGTH STEEL HAVING HIGH UNIFORM ELONGATION

A steel product having a combination of high strength and formability (as measured by percent tensile uniform elongation) is produced by austenitizing a steel consisting essentially of from 0.04 to 0.17% carbon, 0.8 to 2.0% manganese, up to 1.0% silicon, up to 0.12% vanadium, up to 0.1% columbium, up to an effective amount of titanium to form titanium carbonitrides, 0.001 to 0.025% nitrogen, balance essentially iron and then cooling at a rate of no more than about 70 DEG F/sec. to about 850 DEG F and at a rate of more than about 10 DEG F/sec. to transform the freshly formed austenite to a microstructure of from 10 to 35% by volume of martensite and/or lower bainite (MLB), balance essentially proeutectoid ferrite. Slower cooling rates may be employed to obtain the desired microstructure if a restricted chemical composition is used. The heat-treated steel product is characterized by an ultimate tensile strength of 80,000 p.s.i. minimum and a uniform elongation of 16% minimum.