Cooling rate effects on fatigue life prediction using hardness measurements for in-service steel patch-welds with and without TIG dressing treatment

Abstract

In-service patch welding is commonly used to repair corroded or damaged steel infrastructures. However, the in-service conditions may unfavorably affect the long-term mechanical and structural integrity. The present research studies the fatigue behavior of fillet welded patch repairs with and without TIG-dressing (TD). Six types of panels were constructed under various in-service cooling conditions. Specimens cut from the main panels were subjected to high-cycle fatigue, hardness, and metallography tests. The fatigue life of the specimens was also predicted using a novel numerical approach. The model incorporated micro-hardness test data from the weldment section. Macrographic and microhardness data were used for the zoning of the weldment section. The harness data were then employed to define the post-weld mechanical properties of the materials in different weldment zones. The fatigue life was estimated using the microhardness data, stress and strain data obtained from the finite element analysis of the specimen, a UVARM subroutine, and several multiaxial fatigue life prediction models. The numerical fatigue life estimations showed reasonable agreement with the experimental data. Both experimental and numerical modeling results proved significant improvements in the fatigue life of the TD specimens. Regardless of the welding conditions/treatments, the best fatigue life estimates were provided by the BMM, SWT, Glinka, and KBM criteria, respectively.