Ablation oxidation and surface quality during laser polishing of TA15 aviation titanium alloy

Abstract

TA15 titanium alloy is sensitive to temperature, and it is one of the main materials used in aircraft bearing parts that operate for long periods of time at 500 °C. The thermomechanical processing of this alloy is difficult to control because of its high activity and oxidation. In the present research, nanosecond pulse lasers of various powers were used to polish the TA15 surface. The surface morphology, microstructure evolution, oxidation depth and mechanical properties were investigated. The results revealed that the initial sample has a rough surface, and both high-power and low-power lasers can significantly decrease the surface roughness. Three methods, SEM morphology analysis, EDS line scanning and EDS mapping, are used to detect the oxidation depth of the polished zone. The TEM images and XRD patterns show typical Al2O3, Ti2O3 and TiO2 constituents, which affect the tensile strength of the alloy. A low-power laser has a better polishing effect than a high-power laser; the oxidation depth with a high power is approximately 100 μm, while the oxidation depth with a low power is less than 10 μm. The polished surface roughness parameters Ra (arithmetical mean deviation of the profile) and Sa (arithmetical mean height of the scale limited surface) obtained with a low-power laser are reduced from approximately 6 μm–3.197 μm and 4.298 μm, respectively.

Keywords

• Laser polishing
• TA15 alloy
• Surface quality
• Oxidation
• Microstructure