レーザ照射によるチタン合金の表面改質

抄録

This study was conducted to clarify the effect of CO₂ laser irradiation on the wear resistance, corrosion resistance and fatigue strength of Ti-6Al-4V alloy. The results are as follows. (1) Laser irradiation results in formation of a hardened case on the titanium alloy because precoated carbon, oxygen and nitrogen existing in the air rapidly diffuse to the inside during the irradiation. The formation of such a hardened case greatly improves the wear and corrosion resistance of the titanium alloy. (2) Laser irradiation results in a marked decrease in the fatigue strength of the titanium alloy. This is caused by (i) cracking on the surface during the irradiation, and (ii) change of the fine equiaxed microstructure to the widmanstatten microstructure.