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Does PWHT increase the fatigue strength of steel welded joints?

   

Frequently asked questions

There is no increase in fatigue strength for welded joints subjected to entirely tensile applied loading cycles. If the applied loading is partly or wholly compressive, PWHT will be beneficial, provided residual stresses are fully relieved. The relevant UK standard BS7608:1993 'Code of practice for fatigue design and assessment of steel structures' allows 40% of the compressive part of the cyclic stress range to be ignored in estimating the fatigue design life. However, there is a requirement to demonstrate that stress relief is effective, for example by measuring the residual stress adjacent to the joint of interest after PWHT.