EB炉熔炼TC4钛合金轧制过程中的组织演变与力学性能

Microstructure Evolution and Mechanical Properties of TC4 Alloy Prepared by Electron Beam Cold Hearth Furnace During Rolling Process

本实验以电子束冷床熔炼炉(EB炉)熔炼TC4钛合金为研究对象,结合实际生产流程,研究不同变形量和不同温度对TC4钛合金板材显微组织与力学性能的演变规律。结果表明:在相同温度下,随着变形量增加,显微组织中α相的体积分数和尺寸减小而β相体积分数增大,合金的抗拉强度和延伸率均增大;当变形量为30%时,显微组织均表现为片层结构,随着变形温度升高,片层α相长宽比逐渐减小,抗拉强度逐渐升高而延伸率变化不大;当变形量增加到90%时,随着变形温度升高,显微组织由较强的B织构(0002)<1120>转化为T织构(1010)<1120>和锥面织构(1011)<1120>,塑性变形由基面滑移转为柱面滑移,显微组织中α相尺寸减小而β相含量增大,合金的抗拉强度和延伸率均增大。当温度升高到1000℃时,α相完全转变为β相,在随后的冷却过程中细针状次生α相从β晶粒析出,合金的抗拉强度和延伸率均增大。

In this investigation,the effects of the different deformation degree and temperatures on the microstructure evolution and mechanical properties of TC4 titanium alloy fabricated by electron beam cold hearth melting(EBCHM)were investigated.The experimental results showed that as the deformation degree increased at the same temperature,the volume fractions and sizes ofαphase were decreased while the volume fractions ofβphase were increased,and the ultimate tensile strength(UTS)and ductility of this alloy were both increased.When the deformation degree was 30%,all the microstructures with different temperature were presented lamellar structures.As the deformation temperatures increased,the sizes of lamellarαphases were decreased and the UTS of this alloy were gradually increased while the ductility was changed a little.When the defor-mation degree was 90%,as the deformation temperatures increased the microstructures were changed from strong B textures(0002)〈1120〉into T texture(1010)〈1120〉and a small amount of pyramid texture(1011)〈1120〉,the plastic deformation was dominated by the cylindrical slip system and the base slip system.The sizes ofαphase were decreased while the volume fractions ofβphase were increased in these microstructures,and the UTS and ductility of this alloy were both increased.When the temperature increased to 1000℃,αphases were fully transformed intoβphases,the fine-secondary acicularαphases were precipitated fromβphase matrix and the UTS and ductility of this alloy were both increased.