Fe-Alブレーズ溶接の疲労破壊に及ぼす界面状態の影響

抄録

Non-ferrous metals are used in automobile parts for making automobiles lighter and improving fuel efficiency. Braze welding is one of the techniques which can be used to join steel and other different metal. For dissimilar metal joint, the heating during welding process generates intermetallic compounds (IMC) which may cause stress concentration in the interface. For this reason, a dissimilar metal joint could result in weak strength of joint, especially under fatigue loading. As fatigue life is an important parameter for selecting materials in machine or structure, therefore a method for evaluating the fatigue life of dissimilar metal joint is needed. In the previous study done by Fukazawa et al. (2015), fatigue life evaluation of a newly developed FCW (Flux-Cored Wire) braze-welding of Fe-Al joint had been evaluated and several patterns of fatigue failure were reported. However, the mechanism that decides the failure patterns was not investigated. With respect to this, the present work aims to reveal the failure mechanism of the Fe-Al braze-welded specimen due to fatigue loading. The effect of IMC is discussed in detailed by conducting Scanning Electron Microscopy (SEM) analyses. As the results, the existence of IMC containing some voids was revealed. Moreover, crack generated in the interface is observed by SEM image in order to clarify the propagation mechanism.