时效热处理对TC18钛合金组织及力学性能的影响

Effect of aging on microstructure and mechanical properties of TC18 titanium alloy

以TC18钛合金作为研究对象,采用固溶-时效工艺来调整其组织结构,结合X射线衍射(XRD)、金相(OM)、扫描电镜(SEM)、透射电镜(TEM)等分析方法研究时效热处理和晶粒组织对TC18合金力学性能的影响。研究结果表明:铸态合金时效后屈服强度与固溶态的屈服强度相比有所提升,但塑性降低;在空冷固溶条件下,在温度为450℃、时效时间为4 h时,样品的屈服强度增至1 492 MPa,但其延伸率降低;当时效温度为600℃时,样品晶界附近和晶内处出现细纹状次生α相;次生α相的分布和宽度影响合金变形中位错的运动,降低合金强度,提升合金塑性。

Taking TC18 titanium alloy as the research object,the solid solution-ageing process was used to adjust its organisational structure,and the effects of aging heat treatment and grain organisation on the mechanical properties of TC18 alloy were investigated by combining organisational analysis methods such as X-ray diffraction(XRD),metallography(OM),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that the alloy's strength in the as-cast state is enhanced after aging compared to that of the solid solution state,but the plasticity is reduced.Under air-cooled solution conditions,the yield strength of the samples increases to 1492 MPa at the temperature of 450℃and an aging time of 4 h,but their elongation decreases.When the time-effecting temperature is 600℃,there appears fine grain-like secondaryα-phase in the samples near the grain boundary and the intragranular,and the distribution and width of the secondaryα-phase affect the movement of dislocations in the deformation of the alloy,which reduces the alloy strength and improves the plasticity of the alloy.