Hot deformation behavior of Ti-6Al-4V-0.1Ru alloy during isothermal compression

The hot deformation behavior of Ti-6 Al-4 V-0.1 Ru titanium alloy was investigated by isothermal compression tests on a Gleeble-3500 thermal simulator over deformation temperature range of 1023-1423 K and strain rate of 0.01-10 s-1.Arrhenius-type constitutive models were developed for temperature ranges of bothα+βdual phase andβsingle phase at strain of 0.1.Afterwards,a series of material constants(including activation energy Q,material constants n,αand ln A)as polynomial functions of strain were introduced into Arrhenius-type models.Finally,the improved Arrhenius-type models in temperature field ofα+βandβphase were constructed.The results show that the improved Arrhenius-type models contribute to the calculation of Zener-Hollomon(Z)parameter,and the microstructural evolution mechanism is uncovered by combining microstructure observations with Z-parameter.Furthermore,the improved Arrhenius-type models are also helpful to improve the accuracy of finite element method(FEM)simulation in the deformation process of Ti-6 Al-4 V-0.1 Ru titanium alloy.

Effect of heat treatment processing on microstructure and tensile properties of Ti-6Al-4V-10Nb alloy

Effects of heat treatment processing on the microstructure and mechanical properties of Ti-6Al-4V-10Nb alloy were investigated. The microstructures were investigated by SEM, TEM and XRD, and the mechanical properties were evaluated by tensile tests at room and elevated temperatures. The results indicate that the lath-like and globular primary α phase, secondary α phase and β phase are obtained after forging and heat treatment processing. The size of secondary α phase is much smaller than that of primary α phase. After heat treatment, the volume fraction of primary α phase is decreased, and that of secondary α phase is increased. With the increase of solution temperature, the volume fraction of primary α phase is gradually decreased, and that of secondary α phase is obviously increased. The yield strength and tensile strength of Ti-6Al-4V-10Nb alloy are significantly enhanced with the solution temperature increasing.

添加Y元素对Ti-6Al-4V-2Cr-1.5Mo合金组织和力学性能的影响

通过OM、SEM、XRD和TEM对热处理态Ti-6Al-4V-2Cr-1.5Mo-xY(x=0.1,0.5,1.0,1.5,质量分数)合金的组织和力学性能进行分析,发现添加稀土Y元素后,合金的组织得到了明显的细化,产生的稀土氧化物Y_(2)O_(3)弥散分布在基体中;且当Y元素的添加量为0.5%时,合金的强度、硬度和伸长率最好,性能最优。对热处理态的Ti-6Al-4V-2Cr-1.5Mo-0.5Y进行分析,发现析出相Y_(2)O_(3)与基体α-Ti之间的错配度为0.141 3,属于半共格界面。

Y元素对铸造Ti-6Al-4V合金微观组织与力学性能的影响

研究了Y元素合金化对铸造Ti-6Al-4V合金微观组织与力学性能的影响。铸态合金微观组织与力学性能分别利用金相显微镜、扫描电镜、透射电镜和拉伸试验进行表征。结果显示,Ti-6Al-4V合金呈现典型的魏氏组织特征。添加Y元素后,合金中形成Y2O3颗粒并分布在初生β晶粒的晶界处,同时在晶界两侧形成平行的α/β层片结构,而晶粒内部形成相互交叉的α/β层片结构,即Y2O3明显改变了Ti基体片层组织形貌。相比于Ti-6Al-4V合金,添加Y元素之后,合金的屈服强度和抗拉强度稍有提高,但是平行的α/β层片结构和Y2O3颗粒引起合金由解理断裂向沿晶断裂转变,进而导致延伸率显著减小。所以,Ti基体微观组织变化对合金力学性能同样具有重要作用。

汽车用新型钛合金的搅拌摩擦焊研究

进行了6 mm厚汽车新型钛合金Ti-6Al-4V-0.2Y板材的单面对接搅拌摩擦焊试验,并对接头的宏观形貌、X光无损探伤、显微组织、表面硬度和力学性能进行测试与分析。结果表明,钛合金Ti-6Al-4V-0.2Y板材的焊接接头成形好、表面光亮、无明显缺陷、力学性能较佳;接头的室温抗拉强度达到900 MPa、接头系数高达96%;接头硬度最大值位于焊核区、最小值位于前进侧热影响区。