| Abstract Scope |
Metallurgical evaluation plays a critical role in the systematic failure analysis of assemblies that have failed in service. In this study, the root causes of failure at a dissimilar metal weld joint in the Torque Arm Assembly was investigated. The failed assembly primarily consisted of 12-inch blade made of ASTM A36 steel, welded to a hub fabricated from AISI 4140 steel. Welding was performed using the pulse Gas Metal Arc Welding (GMAW) technique with ER70S-6 filler metal.
The scope of the evaluation included visual inspection, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), chemical composition analysis, hardness testing, and metallographic examination.
The investigation concluded that an inadequate welding process led to the formation of a hard and brittle microstructure in the heat-affected zone (HAZ) of the weld joint, ultimately resulting in catastrophic failure. |