Abstract: The potent hardenability effect of manganese and its relatively low cost and availability make it an attractive candidate for the production of high strength steels, especially in the range of about 2.0 to 6.0 percent manganese. The main deterent to the use of such high manganese steels has been their poor toughness. This can be improved by producing steels with high purity or with controlled low carbon contents. However, the requirements of high purity and very low carbon tend to offset, to a large extent, the cost advantage of manganese. The instant invention utilizes an intercritical anneal at a temperature just slightly above austenite start temperature (A.sub.s) in order to form retained austenite at the grain boundaries. The steel is heated at temperatures from the A.sub.s to about A.sub.s + 75.degree. C for time periods varying from as little as one minute to 16 hours, the time being generally inversely proportional to the temperature.

Abstract: Hypoeutectoid steel is heated to an intercritical temperature to produce a microstructure of about 30-50% austenite. The steel is then cooled as rapidly as feasible to a temperature below A.sub.s and held at temperature to transform the austenitic portion. Such transformation may occur either in the minimum of the pearlite region (.about.1200.degree. F) or in the bainite region (.about.800.degree. F).

Abstract: Hot rolled steel rod, containing less than 0.4% C, is cooled by a prescribed, interrupted-cooling procedure for producing rod with enhanced ability to receive cold work. In cooling from the austenite range, the rod is held within a specified, narrow temperature range for a period of at least about 2 minutes. The particular holding range is shown to be a function of carbon content, whereby low carbon steels (<0.28% C) are held at a prescribed temperature above 1,450.degree.F, while medium carbon steels are held at a temperature of about 1,250.degree.F.