Influence of Cu and Ni on the Microstructure and Mechanical Properties of an HSLA Steel

In this research the role of alloying elements on the microstructure and mechanical properties of an as cast and hot rolled high strength low alloy (HSLA) steel was studied. Different compositions with different amount of copper in the presence of nickel, hot rolled and quenched in oil. Tensile test, hardness test, scanning electron microscope (SEM) and optical microscope (OM) were used to evaluate different properties of each sample. The results showed that, all the samples revealed a ferriteperlite structure in as cast structure, however finer structure with higher hardness was seen in the samples with higher amount of copper. Furthermore, in hot rolled samples, it was seen that addition of nickel and copper resulted in grain refinement. A remarkable drop was seen in elongation due to copper precipitation. Fractography also revealed that, increasing copper amount led to variation of fracture mechanism from ductile to shear ductile fracture.