1995 Volume 13 Issue 3 Pages 456-462
Though friction welded butt joints have come into wider use machine elements and structural members, valid evaluation method of the joint performance, especially under service load conditions, has not been established yet. The reliability of this type of joint has been supported only by empirical knowledge accumulated up to the present. In order to clarify the fatigue behaviors of the joint, we have carried out a series of fatigue tests on several sorts of friction-welded butt joints in ordinaly atmospheric environment, and have revealed that the fatigue strength of the joint is higher than that of the base metal, but the lives show the large scatter. Evaluation of corrosion fatigue behavior of frictionwelded joints is also an urgent issue, because some of the joints are practically used in corrosive environments.
The main aim of this study is to reveal the relationship between the fiber flow conditions near the weld interface of the joint and their corrosion fatigue resistance. For this purpose, a series of experiments was carried out on four friction-welded butt joint specimens composed of a similar structural carbon steel fabricated by different friction welding conditions. This study covers following four phases : (1) Dependence of fiber flow conditions on friction welding procedure, (2) corrosion responce of the four joints fabricated by different friction welding procedures, (3) fatigue strength behavior of joints with corrosion pits in ordinaly atmospheric environment, and (4) corrosion fatigue resistance of respective joint.
The results of this study revealed that the corrosion fatigue resistance of the joint was well correlated with the fiber flow conditions of the joint; many and deep corrosion pits were generated on the surface area intersecting the fiber flow and the notch effect of the corrosion pits resulted in the reduction of fatigue strength. In other words, joint specimen wishout the surface area intersecting the fiber flow shows excellent corrosion fatigue performance.
