Tempering characteristics of two low-alloy steels used for naval applications

Tempering characteristics of two high-strength low-alloy steels (HY-80 and HX-80) with carbon contents of 0.14 and 0.07%, respectively, have been investigated by transmission electron microscopic analysis. Mechanical properties such as hardness, and tensile and impact properties of these two steels were correlated with microstructural features. It was observed that the major factors contributing to the equivalent strength, better toughness, and weldability of microalloyed HX-80 steel compared to HY-80 steel include judicious selection of tempering temperature, lower carbon content, and finer grain size.