SYMPOSIA PAPER Published: 01 January 1982
STP30099S

Influence of Tensile Residual Stresses on the Fatigue Behavior of Welded Joints in Steel

Source

Fatigue tests were carried out on fillet welded joints in four steels, with yield strengths ranging from 332 to 727 N/mm2, under various applied load ratios. Some specimens were stress-relieved but most were spot-heated to ensure that high tensile residual stresses, as would be present in as-welded joints in real structures, were present in the specimens. The aim was to investigate the effect of tensile residual stresses on the fatigue behavior of fillet welded joints under different load ratios and the relevance of the tensile strength of the steel, particularly in relation to the magnitude of residual stresses developed.

In the present specimens, the residual stresses were no higher in the high-strength steels than the mild steels, with the result that the tensile strength of the steel had no effect on the fatigue strength of the joints in both the as-welded and the stress-relieved conditions. Furthermore, it was found that for the range of R-values used (R = −∞ (zero compression to R = 0.67) applied load ratio had little effect on the fatigue strength of the as-welded joints provided that “failure” under compressive loading was taken to be a crack length less than or equal to that at which the rate of crack growth began to decrease. Stress relief was only partially effective, with the result that applied compressive stresses were still damaging. Thus under partly compressive loading the fatigue strength of the joint increased but not greatly. However, stress relief had no effect on the fatigue strength of the joint when it was subjected to tension loading.

Author Information

Maddox, SJ
The Welding Institute, Cambridge, England
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Developed by Committee: E08
Pages: 63–96
DOI: 10.1520/STP30099S
ISBN-EB: 978-0-8031-4841-3
ISBN-13: 978-0-8031-0711-3