Abstract: Bars of titanium alloys suited for the manufacture of at least the stems (2), (3) of engine valves are mass-producible while maintaining good configurational and dimensional accuracies throughout the valve fabricating process and the wear-resistance imparting processes to at least the stems (2), (3), by surface oxidizing and nitriding. The alloys are of the .alpha.+.beta. type whose microstructure consists of any of an acicular .alpha.-phase consisting of acicular .alpha. crystals having a width of not smaller than 1 .mu.m, an acicular .alpha.-phase consisting of acicular .alpha. crystals having a width of not smaller than 1 .mu.m and dispersed with equiaxed .alpha. crystals, and an equiaxed .alpha.-phase consisting of .alpha. crystals whose diameter is not smaller than 6 .mu.m. Their microstructure may also include one in which the diameter of the pre-.beta. crystals in the acicular .alpha.-phase is not larger than 300 .mu.m and the width of the acicular .alpha. crystals is not smaller than 1 .mu.