Role of powder bed thickness and deposition direction on the corrosion behavior of selective laser melted (SLM) Ti-6Al-4V alloy : Experiments and simulations

Abstract

Additive Manufacturing (AM) or rapid prototyping or 3D printing is an advanced manufacturing technique for producing near net shape components with minimal finishing operations unlike the substractive manufacturing routes. One of the unique advantage of this method, in contrast to the conventional manufacturing techniques is Its capability to fabricate parts directly from computer-aided design (CAD) data. Selective laser melting (SLM) is one of the several AM techniques which selectively melts the powder bed (layer by layer) to obtain the neat net shape components. Besides the ease of the manufacturing, SLM can generate lots of microstructural architectures and intricate shapes and hence one of the most popularly used AM method. Many of the metals and alloys such as steels, Al alloys, Ti alloys have been manufactured using SLM techniques whose mechanical properties have been investigated quite extensively. In the current work, our focus is to investigatethe corrosion response of Ti-6Al-4V alloys manufactured via SLM method. Titanium and its alloys have widespread applications in lightweight structural applications due to their high specific strength (almost comparable to superalloys), elevated temperature mechanical properties, good corrosion resistance (even for saline water), bio-compatibility and non-magnetic properties. These properties make them suitable candidates for aerospace applications, chemical processing plants, biomedical applications. the Ti-6Al-4V is an α+β titanium alloy comprising of 6% Al and 4% V is most widely used for industrial applications due to its excellent mechanical properties compared to the other Ti alloys. Corrosion is an ever-present problem in all different environments, particularly in marine, bio-implant, and aviation applications. In this work, corrosion behavior of Ti-6Al-4V alloy manufactured using SLM technique with layer thickness of 30 μm and 60 μm with scan rotation 67o, was investigated. The change in thickness has a marked effect on the microstructure on the microstructure and hence the corrosion properties.Electrochemical results show that 3067 samples have a higher corrosion rate than the B6067. Further corrosion simulations were conducted using COMSOL Multiphysics software and compared with the experimental results.