Study on the Behavior of Plastic Strain at the Bonded Part of Dissimilar Welded Joint during the Fatigue Test

Fractured Positions for High and Low Cycle Fatigue Tests

Abstract

This report presents results of the fatigue test on the dissimilar welded joint (Mild Steel & AISI304 Steel) with smoothed plane test specimens.
Generally, it is well known that the accumulation of the microscopic plastic strain occurs during the fatigue test.
Then we observed the degree of the plastic deformation caused by difference of microstructures at the bonded part of the dissimilar welded joint by micro-interference method and also discussed the fractured position for each high and low cycle fatigue tests.
The results obtained from this experiment are-summarized as follows;
(1) We can sufficiently obtain the qualified behavior of plastic strain occurred at the bonded part by micro-interference method.
(2) Generally speaking, we are apt to consider that the bonded part will be, weakest. But according to our experiments fracture occurred near the center of mild steel part in case of low cycle fatigue; on the while fracture occurred at the bonded part in the case of high cycle fatigue (Photo 8).