The effects of solution treatment (ST) and cold rolling (CR) on structure and tensile properties of a heavily hot-rolled (HR) Ti–7.5Mo alloy were investigated. Experimental results indicated that, after HR… Click to show full abstract
The effects of solution treatment (ST) and cold rolling (CR) on structure and tensile properties of a heavily hot-rolled (HR) Ti–7.5Mo alloy were investigated. Experimental results indicated that, after HR with a one-pass 65% reduction in thickness, the pores in as-received samples substantially disappeared, the misorientation angle distribution became broader, and grain texture shifted toward $$\left\langle {10\bar{1}0} \right\rangle$$101¯0. Post-HR ST produced an orthorhombic α″-phase with fine needle-type morphology and caused misorientation to narrow down to 55°–65° with substantially random texture; post-ST CR caused misorientation shift toward high-angle side and texture toward $$\left\langle {10\bar{1}0} \right\rangle$$101¯0 and $$\left\langle {2\bar{1} \bar{1}0} \right\rangle$$21¯1¯0. With an increase in reduction in thickness, α′(102) intensity increased at the expense of two adjacent (112)/(022) α′′-peaks. All X-ray diffraction, metallography and electron backscattered diffraction on scanning electron microscope results indicated that pre-ST HR did not affect the formation of the desired low-modulus α′′-phase when the alloy was subsequently solution-treated. From a practical point of view, the most optimal tensile properties may be found in the sample solution-treated at 900 °C for 30 min and cold-rolled by a 20% reduction in thickness, which demonstrated a yield strength of 924 MPa, an ultimate tensile strength of 933 MPa, a tensile modulus of 73 GPa, and an elongation of 26%.
               
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