The Effect Of Aging Treatment On The Microstructure And Properties Of Copper Precipitation Strengthened Hsla High Strength Low Alloy Steel

The high strength low alloy (HSLA) steels which are being developed as replacements for the HY family of steels are low carbon steels which derive their strength in part due to the precipitation of fine coherent copper particles formed during a quench and aging heat treatment. HSLA-100 is being developed to meet the strength and toughness requirements of HY-100 but can easily welded without preheat, thereby reducing fabrication costs. This investigation uses light and electron microscopy for microstructural characterization while tensile, Charpy, and hardness tests are relied upon for the mechanical properties. The microstructure and mechanical characteristics of HSLA-100 after aging at several different temperatures was correlated. A high ductility and the minimum 100 ksi yield strength was found after aging at 675 C, although this temperature was found to be close to the low eutectoid temperature displayed by HSLA-100. Splitting was observed in the tensile fracture surfaces but the mechanical properties were not adversely affected. (jes).