Effect of Cold Rolling and Heat Treatment on Microstructures and Mechanical Properties in Ti-13Cr-1Fe-3Al Alloys

Thermomechanical processing is effective for improving the strength and toughness in metallic materials due to grain refinement. The strength ductility balance in beta-type titanium alloys can be enhanced by refinement of the beta matrix grain size and alpha precipitation by aging. For improving the strength-ductility balance in Ti-13Cr-1Fe-3Al alloys, the effects of beta grain size on isothermal aging behavior and mechanical properties in Ti-13Cr-1Fe-3Al alloys were investigated. The beta grain size was decreased by the following treatments: 50% CR -> 1073K-1. 8ks, 70% CR -> 1048K-3. 6ks and 70%CR -> 1048K-0. 6ks. Resistivity (rho(RT) and rho(LN)) and resistivity ratio (rho(LN)/rho(RT)) in the 84,71 and 40 mu m specimens started decreasing later than in the 309 mu m specimen with isothermal aging at 673K. Tensile properties were not sensitive to the beta matrix grain size in the STQ and recrystallized states. In the STQ and recrystallized specimens, the tensile strength and elongation were roughly 800MPa and 30%, respectively. Specimens after aging showed higher tensile strength and lower elongation compared to the STQ ones. The specimen with the beta grain size of 40 mu m after aging at 673K for 600ks showed good strength-ductility balance in all specimens.