The effect of alloy composition and heat treatment on the structure and properties of a set of high strength low alloy (HSLA) steels has been investigated. By addition of a relatively high dose of niobium (0·17–0·23%)along with nickel (0·2%), chromium (0·4–0·6%), and manganese (1·5–1·8%) to 0·2%steels, it is possible to develop high strength forging grade steels having baintic or autotempered martensitic matrixes. The microstructure and mechanical properties of these steels are sensitive to cooling rate and heat treatment.
