Abstract
The current study investigates the load controlled fatigue properties of the microplasma arc welded thin titanium Grade 5 (6Al-4V) sheets. In order to explore the effect of weld geometry on the fatigue, two different welded joints were used in the experimental studies. Load controlled fatigue test results were evaluated to present an outlook on the behaviour of microplasma welded titanium alloy Grade 5 sheets under cyclic loading. Even though the previously published monotonic tests showed successful use of microplasma arc welding to join thin titanium Grade 5 sheets with mechanical properties comparable to the base metal, fatigue life of the welded joints was lower than the lives of samples without welds. In particular, the fatigue performance of overlap joints was very poor. This was presumed to be due to the changed material properties of the heat affected zone which was formed by the excess heat of the welding process as fractures often occurred at such locations. Based on experimental findings and fractographic observations, a clear adverse effect of welding process in material behaviour was discovered. Despite the concentrated heat of microplasma arc welding, post-weld heat treatment of the weld area is recommended to improve the mechanical behaviour of the welded joints.
Highlights
Titanium alloys are often preferred in industry for their relatively high specific strength and corrosion resistance, especially in industries where the weight of the components is very important such as aerospace and marine engineering constructions [1,2,3]
Due to the biocompatibility of titanium, it is often used in the making of medical implants [4]
The aim of the study was to achieve a basic level of understanding regarding fatigue of titanium welded joints
Summary
Titanium alloys are often preferred in industry for their relatively high specific strength and corrosion resistance, especially in industries where the weight of the components is very important such as aerospace and marine engineering constructions [1,2,3]. In continuation to the authors’ previous study [5], which investigated the monotonic material properties of welded thin titanium alloy Grade 5 (6Al-4V) samples, the same material was selected once again because of its availability and wide range of applications. In order to manufacture the welded test samples from the chosen material, microplasma arc welding was used. This welding method is a low current variation of widely used plasma arc welding with a specialized, highly precise plasma torch. The advantage of microplasma arc welding method is a very concentrated plasma arc and welding heat. Thin sheets which are relatively more susceptible to heat-related welding distortions and adverse effects of the heat-affected zone (HAZ) can be welded with microplasma arc welding
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