Mechanical properties of 304L stainless steel SMAW joints under dynamic impact loading

Abstract

The impact properties of 304L Stainless Steel Shielded Metal Arc Welded (SMAW) joints are studied at strain rates between 10^{− 3} and 7.5× 10³ s^{− 1} using a compressive split-Hopkinson bar. The effects of strain rate on the flow response and fracture characteristics are fully evaluated. The results show that the tested weldments exhibit a pronounced strain rate sensitivity, and that changes in the strain rate result in a difference in the flow stress, fracture strain, and work hardening rate. Furthermore, it is noted that the strain rate sensitivity and activation volume vary with the magnitude of the strain rate, and are related to different work hardening stress levels. At all values of strain rate, the tested weldments fail as a result of adiabatic shearing, in which cracks initiate within the shear band and then propagate along this shear band until failure occurs. Observation of the fractured specimens reveals that the fracture surfaces of the fusion zone and base metal regions are characterized by the presence of elongated dimples. The variation in the observed dimple features with strain rate is consistent with the results of the impact stress-strain curves.