Corrosion Behaviour of Selective Laser Melted TC4 Alloy

Abstract

TC4 alloy samples were built by selective laser melting (SLM). The microstructure was observed, and electrochemical measurements were performed to investigate the corrosion resistance of SLMed TC4 alloy in different forming surface and roughness. The traditional rolled sample was introduced as a reference. Results show that processing method, forming surface and roughness act a significant role in influencing the corrosion resistance. The microstructure of SLMed TC4 on vertical section consists of the primitive columnar β grains filled with a large number of acicular α' martensites oriented at approximately ±45° with building direction. Unlike the typical α+β phase of traditional rolled sample, a chessboard pattern is observed on cross-section of SLMed TC4. The electrochemical results suggest that the corrosion resistance of traditional rolled sample is superior to that of SLMed sample. SLMed TC4 sample exhibits a better corrosion resistance on the vertical section, compared with the cross-section. Besides, the SLMed sample with rougher surface exhibits poorer corrosion resistance. Obvious etch pit is found on the surface of SLMed sample and the corrosion morphology is pitting.

Keywords

• additive manufacturing
• titanium alloy
• corrosion resistance
• polarization curve