| 摘要 |
<p>A titanium alloy bar which is excellent in the dimensional and configurational precision in manufacturing an engine valve and in the wearproofing treatment comprising the oxidation or nitridation of the surface, thus being suitable for mass producing engine valves. The bar is one made from an α+β-type titanium alloy and having a microtexture selected from among an acicular α-crystal texture wherein the α-crystal has the width of 1 νm or above, another acicular α-crystal texture wherein the α-crystal has the width of 1 νm or above and isometric α-crystals are dispersed, and an isometric α-crystal texture wherein the α-crystal grain has the diameter of 6 νm or above. This bar can be produced most efficiently by limiting the diameter of the β-crystal grain in the acicular α-crystal texture in the microtexture of the bar to 300 νm or less and the width of the acicular α-crystal to be in the range of 1 νm to 4 νm.</p> |
