Determination of mechanical properties in SM490 steel weld zone using nanoindentation and FE analysis

Nanoindentation, tensile test, finite element (FE) analysis, and optical microscopy examination were carried out to investigate the mechanical properties in an SM490 steel weld zone. Three indentation series were performed across the weld zone including the base metal (BM), heat-affected zone (HAZ), and weld metal (WM). The mechanical properties (E, H, σy, and n) were then estimated from the load-penetration depth data of nanoindentation and FE analysis results. The tensile tests of SM490 and welded specimens were conducted and the equivalent modulus of the weld zone was interpreted from the composite action of BM, HAZ, and WM. The results from nanoindentation showed that WM has the highest values of mechanical properties (E, H, σy, and n), BM has the lowest mechanical properties values, while the mechanical properties within HAZ gradually decrease from the WM to BM region. The effect of microstructural changes due to the weld on the mechanical properties in the weld zone was also discussed.