拉伸塑性对TC11 500℃低循环应变疲劳的影响

 测定了TC11合金经不同制度热处理后试样的500℃低循环应变疲劳的△ε_t～N_f曲线,在不同的△ε_t值条件下,拟合出N_f与φ、δ_5之间的经验关系式。结果指出:强度相近时,合金的塑性越低,其500℃时的N_f越低;虽然魏氏组织500℃的N_f一般低于等轴组织,但若魏氏组织中的片状α或束域比较细小时,其500℃N_f值可明显提高,并与等轴组织的差别缩小。

EFFECT OF TENSILE DUCTILITIES ON THE LIFE OF LOW CYCLE FATIGUE AT 500℃ FOR TC_(11) TITANIUM ALLOY

The low-cycle fatigue curves (Δεt) of titanium alloy TC11 (Ti-6.5 Al - 3.5Mo - 1.5Zr - 0.25Si alloy) at 500℃ are determined under different conditions of heat treatment. The linear empirical formulas between the fatigue life Nf and the tensile ductilities, i. e. and (?), are given under different values of total strain range Δε. The important experimental results show that under different conditions of heat treatment the Nf of titanium alloy TC11 at 500℃ decreases with the reduction of tensile ductilities of the alloy as these samples approach to same magnitude of tensile strength, it is especially pointed out that the Nf of Widmanstatten strueture at 500℃ is generally shorter than equiaxed grain α structure which has a higher tensile ductjlity, but the Af of Widman-statten structure at 500℃ between them decreases if the thickness of α needles is thiner and the size of colonies is finer in the widmanstatten structure.