Experimental investigation on the influence of welding residual stresses on fatigue for two different weld geometries

Abstract

Fatigue tests on welded small-scale specimens often do not show a distinct residual stress influence. An exception is longitudinal stiffeners, which are therefore frequently used to study the influence of welding residual stresses on fatigue. The results are not directly transferable to other weld geometries because the residual stress distribution depends on the weld geometries. In the presented investigation, fatigue tests on multilayer K-butt weld and longitudinal stiffener specimens were performed. The tests were carried out in the as-welded and stress-relieved conditions at different load ratios. Initiation of macroscopic cracks was detected using digital image correlation. This allowed determining the influence of welding residual stresses on the initiation of macroscopic cracks, crack propagation and total fatigue life for both investigated weld geometries.

Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress

“…Interesting to observe, however, the slope of the as‐built PBF‐LB/M is steeper for R = −1 than for R = 0, while the opposite is true for the wrought material. This effect can be related to residual stresses in the PBF‐LB/M specimens and is known from tests of welded specimens at different stress ratios; see Friedrich 50 . Furthermore, the shallow slope of the wrought material S–N curve led to a large number of run‐outs for R = −1.…”

“…This effect can be related to residual stresses in the PBF-LB/M specimens and is known from tests of welded specimens at different stress ratios; see Friedrich. 50 Furthermore, the shallow slope of the wrought material S-N curve led to a large number of run-outs for R = À1. A common way of presenting fatigue test results for different stress ratios is the Haigh diagram.…”

A Numerical Simulation of the Seismic Performance and Residual Stress of Welded Joints in Building Steel Structures Based on the Finite Element Method

“…Meanwhile, the effects of different bending angles and welding paths on RS distribution were compared and analyzed, and the results showed that this method provided valuable reference for engineers and scientists working in the field of RS. Friedrich N et al [18] proposed to reveal the effect of welding RS on the initiation and propagation of fatigue cracks by comparing samples with different weld geometries, and conducting fatigue tests on multi-layer K-shaped butt welds and longitudinal stiffener samples. The results showed that, when there were the same number of cycles, samples in the welded state were more prone to the initiation of macroscopic cracks than those in the stress-relieved state.…”

A frequency‐domain approach for damage detection in welded structures

“…However, as is well‐known, the fatigue strength of a welded component in presence of multiaxial cyclic loading is significantly lower than that of an unwelded one (even if the components are made of the same material) 2 . In particular, the factors causing the above strength reduction 3–5 are residual stresses, 6–9 thermal distortions, 10 defects caused by partial penetration, 11 and material microstructural imperfections 12 …”

“…1 However, as is wellknown, the fatigue strength of a welded component in presence of multiaxial cyclic loading is significantly lower than that of an unwelded one (even if the components are made of the same material). 2 In particular, the factors causing the above strength reduction [3][4][5] are residual stresses, [6][7][8][9] thermal distortions, 10 defects caused by partial penetration, 11 and material microstructural imperfections. 12 Moreover, complex time variable load histories applied to welded components result in severe stress/ strain gradients at the weld toes/roots leading to fatigue damage near such critical regions.…”