Mechanical Properties and Electrical Conductivity of α plus β Titanium Alloy Sheet Regulated by Heat Treatment

Eddy current loss, which produces Joule heat and reduces transmission efficiency, is inevitable when the magnetic coupling is running. Magnetic couplings with high electrical resistivity alloys, such as titanium alloy, have been proven to be effective in suppressing the eddy currents. The Ti-6Al-3Mo-2V-1Cr-2Sn-2Zr alloy sheet was a alpha + beta titanium alloy for marine engineering with high specific strength and electrical resistivity, which was used in magnetic couplings to suppress the eddy currents. In this study, the effect of annealing temperature on the microstructure, mechanical properties, and electrical conductivity of the Ti-6Al-3Mo-2V-1Cr-2Sn-2Zr alloy sheet was investigated. The results revealed that the band structure was arranged along the rolling direction (RD), and the as-rolled titanium alloy sheet showed a typical T-type texture with the c-axis of the alpha phase approximately parallel to the transverse direction (TD). A considerable increase in tensile strength and decrease in elongation after alpha + beta region (850-920 degrees C) annealing was thought to result from the strengthening of secondary alpha/beta interfaces in the bimodal structure. Simultaneously, the alpha phase showed both T-type and R-type textures, which also resulted in higher yield strength along the TD of the sheet. Additionally, when the sheet suffered a beta phase region annealing (950-1000 degrees C), the elongation immediately decreased due to the coarseness and precipitation of the secondary alpha and grain boundary alpha phases, respectively. Meanwhile, the annealed sheet showed an R-type and a new B-type texture components with basal poles rotated 20 degrees-30 degrees away from the normal direction (ND) toward the RD under the influence of variant selection of secondary alpha phase. However, the yield strength along the TD was still higher than that in the RD, indicating that the effect of texture on yield strength anisotropy was reduced. Finally, the electrical resistivity analysis of the titanium alloy sheet indicated that the electrical resistivity along the RD of the sheet was higher when the band structure was formed and the c-axis of the alpha phase was concentrated in the TD. However, the disappearance of the band structure and the increase in the volume fraction of the R-type texture will reduce the anisotropy of electrical resistivity.