Effect of Size and Location of a Weld Defect on Fatigue Life for Argon-Arc Welded Titanium Alloy Joint

Abstract

Analytical studies were made on effect of size and location of a weld defect on fatigue life for argon-arc welded titanium alloy joint. In the analyses, a weld defect was assumed as an initial crack, and the crack growth life was taken as total fatigue life. By using the Isida and Noguchi’s stress intensity factor solution for a plate containing an embedded elliptical subsurface crack under tension, the life prediction code FASTRAN3.9 was revised. A small crack methodology based on the plasticity-induced crack-closure concept and the effective stress intensity factor range, Keff , was used to predict the total fatigue life of welded joint, and to study the effect of the size and location of weld defect on fatigue life by means of the revised FASTRAN3.9 code. Limited amounts of experimental data were used to make comparison with the predictions. The predicted fatigue lives are in reasonable agreement with experiments, and the effect of both the size and location of the weld defect on fatigue life was found to be significant.

The Effect of Manufacturing Defects on the Fatigue Behaviour of Ti-6Al-4V Specimens Fabricated Using Selective Laser Melting

“…4(b)), the fatigue life was increased from 155,354 cycles to 213,009 cycles. This result was similar to that by Liu et al [5]. The experimental results demonstrate that the location of the LOF defect had an influence on the fatigue life of the specimens.…”

Fatigue Strength Dependence on Microstructure and Defects in Ti‐6Al‐4V Welds

“…As shown in Fig. 6a) and by Fan et al [6] and Liu et al [7], small internal pores are less detrimental than surface pores. Three transverse TIG samples had crack initiation at the surface with no visible defects.…”

“…In case the distance from the surface is in the order of the pore's largest dimension, the effect of a surface on plastic strain levels out. Liu et al [7] showed that the fatigue life of titanium alloy welds decreases as the pore size increases and the distance to the surface decreases. In their simulation for pore sizes of 50-100 µm, the effect of distance increased sharply when the distance to a surface decreased below 400 µm.…”