HSLA-100 STEELS - INFLUENCE OF AGING HEAT-TREATMENT ON MICROSTRUCTUREAND PROPERTIES

The structural steels used in critical construction applications have traditionally been heat-treated low-alloy steels, These normalized and /or quenched and tempered steels derive strength from their carbon con tents, Carbon is a very efficient and cost-effective element for incre asing strength in ferrite-pearlite or tempered martensitic structures, but it is associated with poor notch toughness, Furthermore, it is we ll known that both the overall weldability and weldment toughness are inversely related to the carbon equivalent values, especially at high carbon contents, The stringent control needed for the welding of these traditional steels is one of the major causes of high fabrication cos ts. In order to reduce fabrication cost while simultaneously improving the quality of structural steels, a new family of high-strength low-a lloy steels with copper additions (HSLA-100) has been developed, The a lloy design philosophy of the new steels includes a reduction in the c arbon content, which improves toughness and weldability.