两相区热处理对TC4-DT钛合金断裂韧性的影响

Effect of Heat Treatment in α+β Zone on Fracture Toughness of TC4-DT Titanium Alloy

主要讨论了TC4-DT钛合金中初生α相的形态和数量对合金断裂韧性的影响。试验通过相变点以下不同温度的热处理获得不同的微观组织,分析组织中α相的形态和数量对合金断裂韧性的影响规律。结果表明:两相区不同温度热处理,随着固溶温度升高,初生α相含量降低,晶粒尺寸变化不大,次生α相含量增加,长宽比增加,断裂韧性增加。相变点以下炉冷处理,显微组织比同条件处理的空冷组织的初生α相晶粒尺寸增大,片层α相厚度增加,合金的断裂韧性明显提高,并通过裂纹扩展断口进行了断裂机理分析。

Effect of morphology and quantity of the primary α phase in TC4-DT titanium alloy on fracture toughness was discussed. Different α phase contents were obtained by heat treatment below phase transition point. The results show that contents of primary α phase drop with solution temperature increasing, and the size of grains changes little. The content of secondary α phase increases, and length-width radio increases with solution temperature increasing, which increases the fracture toughness. Compared with the alloy under air cooling, the alloy under furnace cooling exhibits larger primary α phase, thicker lamellar α, and much higher fracture toughness. Then the growth mechanism was analyzed through fracture.