Optimizing the Corrosion Resistance and Hardness of Ta31 Alloy by Selective Laser Melting

Abstract

The use of novel near-α TA31 titanium alloys has gained widespread attention as marine equipment is exposed to increasingly harsh operating conditions. In particular, TA31 alloys manufactured by selective laser melting (SLM) technology show significant potential for future applications in such environments, offering promising solutions for marine equipment. Corrosion resistance plays a vital role in mitigating the effects of marine corrosion, while hardness is critical for withstanding mechanical stresses in marine applications. However, no reports have specifically examined the corrosion behaviour and hardness of TA31 alloys produced by SLM in seawater environments. In this work, SLM TA31 alloys were fabricated by varying the laser scanning speed while maintaining a constant laser power. Two well-formed SLM TA31 alloys were selected for detailed investigation of their corrosion resistance and hardness, with rolled TA31 alloys used as a benchmark for comparison. The results showed that the SLM TA31 alloy fabricated at a scanning speed of 900 mm/s exhibited the best corrosion resistance and improved hardness, while that fabricated at 1000 mm/s showed the poorest corrosion resistance but still had enhanced hardness compared to the rolled alloy. The observed differences in corrosion resistance among the SLM TA31 alloys were attributed to the combined effects of the metastable martensite a' phase content and the variation in grain boundary number within the microstructure. The improved hardness was primarily due to grain refinement and the formation of harder acicular martensite α' phase.

Keywords: Keywords: TA31 alloy, SLM technology, Corrosion resistance, hardness