Evaluation Of Surface Treatment Of Ti-6Al-4V Alloy Specimens

Abstract

As is generally well known, though titanium and its alloys have high specific tensile strength, excellent corrosion resistance, etc., they have not been widely used until now mainly due to their extremely high processing cost. Therefore, it is considered that the above barrier will become smaller if it is possible to improve the mechanical properties of Ti-alloys by applying surface treatments on them. The purpose of this paper is to improve and to evaluate the mechanical properties, especially fatigue strength of about 6 lunds of surface-treated Ti-6A14V alloys. That is, surface treatments by 2 kinds of plasma, 3 kinds of DLC (diamond-like carbon) coating and the electroless plating method, have been studied for Ti-6A1-4V alloy. This study presents an analysis of fatigue behavior from the viewpoint of micro-hardness and adhesion work through a new technique in Ti-6A1-4V alloy. In addition, the specimen's surface has been successively observed by the replica method during tests and it seems clear that the fatigue strength is improved by the DLC treatment in comparison with that of the conventional Ti-6A1-4V alloy by about 20% (fatigue limit improvement by 70 MPa). Though all the hardness value of these specimens increased, the fatigue limit improved only in the cases of two kinds of specimens by DLC coating.