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 percent) along with nickel (0.2 percent) chromium (0.4-0.6 percent), and manganese (1.5-1.8 percent) to 0.2 percent 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.
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