Abstract
The strain distribution and the strain concentration factor in friction welded specimens were examined by copper-electroplating technique. The influence of strain concentration on the fatigue damage by cyclic stressing was investigated. The tests were carried out by rotary bending, using specimens of mild steel with a smooth welded joint.
The results obtained are summarized as follows:
(1) The strain distribution in the friction welded specimen is affected by the micro-structure of the material. The strain becomes minimum at the weld interface, and increases with an increase in distance from the interface.
(2) The strain concentration factor is maximum in the parent material and minimum at the weld interface. The difference, however, is not so remarkable.
(3) The slip-lines in the specimen appear more densely in order of magnitude of the concentrated strain. The fatigue fracture of the specimen occurs at the location where the strain concentration factor is maximum and the fatigue crack propagates more rapidly.
