In this investigation, the fatigue and fatigue crack growth tests were performed for the SMAW, GMAW and FCAW butt joints of HSLA steel. The test was conducted for five different stress levels varying from 50 - 90 % of yield strength at a stress ratio of R = 0.1.

The fatigue S-N and dA/dN curves were constructed from the experimental data. The mechanical properties such as tensile strength, impact strength, and microhardness were evaluated as per the ASTM standard and correlated with the fatigue properties of welded joints.

The maximum obtained fatigue strength of SMAW, GMAW and FCAW joints is about 310 MPa 322 MPa and 329 MPa for the unnotched specimens. From the experimental results, the FCAW recorded higher fatigue strength, which is 6% and 9 % higher fatigue strength than GMAW and SMAW joints. Similarly, the higher critical SIF observed in fatigue crack growth of the FCAW joint was 18 MPavm at 10-3 mm/cycle. It is 9.5 % and 14% higher than GMAW and SMAW joints.

This is due to better fatigue properties and lower crack acceleration rate than other welding processes.

This article is shared by P. Hariprasath, P. Sivaraj, V. Balasubramanian, Srinivas Pilli and K. Sridhar