Studies on Friction Welding of Carbon and Alloy Steels : 3rd Report : Adequate Welding Conditions for High Alloy Steels and Distributions of Alloy Elements near Weld Interface

Abstract

In order to obtain adequate friction-welding conditions for high alloy steels, an austenitic stainless steel (SUS304), a martensitic stainless steel (SUS440C), a high-speed steel (SKH9) and a 0.45% carbon steel (S45C) were used as test materials. The adequate welding conditions under which friction welded joints with sufficient strength in both static and cyclic loading could be obtained were established and shown in terms of the friction coefficient μ^^(SUB) at the rubbing surfaces just before upsetting. The limit of the adequate welding conditions was μ^^(SUB)≤0.08 for material combinations of (SUS304-S45C), (SUS440C-S45C), (SKH9-S45C) and (SUS304-SUS304) in the case of round bars with diameters in the range of 13 to 20mm. Two kinds of welded joints with and without sufficient strength were examined using an X-ray micro-analyzer with a scanning electron microscope, and the distributions of the alloy elements at and near the weld interface were compared. It was clearly shown that the distributions closely related to the welding conditions, and that the adequate welding conditions shown in terms of the friction coefficient are very effective in practice.