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Three kinds of titanium-molybdenum alloy, Ti-8Mo, Ti-14Mo and Ti-20Mo (mass%), quenched from 1223 K were investigated to clarify the tensile behavior and the cold workability using tensile test and conical cup test. In the quenched state Ti-14Mo showed the superior workability. Ti-20Mo has poor ductility in tensile test, but has relatively good formability in conical cup test. Both Ti-8Mo and Ti-14Mo became brittle through a cold rolling of 50% reduction in thickness; however Ti-20Mo did not change in workability by the cold rolling at all. Hardness remarkably increased with rolling reduction in Ti-8Mo and Ti-14Mo, but was almost constant in Ti-20Mo, especially with Ti-20Mo containing high oxygen. Microstructure of Ti-8Mo and Ti-14Mo rolled until seventy-odd percentage exhibited very fine structure and changed to 0 þ and structure, respectively. On the other hand Ti-20Mo hardly changed in microstructure by a cold rolling besides the formation of some band-like products. The product was composed of single variant of commensurate !-phase, whereas the matrix contained four variants of incommensurate !-phase. It was suggested that the peculiar deformation mechanism of Ti-20Mo was concerned with stress induced transformation of the !-phase.

The workpiece surface topography is an important factor controlling the mechanisms of lubrication in metal forming processes. In the present work, the microscopic lubrication mechanisms induced by lubricant trapped in pockets of the surface in strip drawing are studied. The experiments are performed with macroscopic model pockets in the surface studying the influence of the shape of the pockets on the lubrication mechanisms. A large radius of curvature on the rear edge and a small angle to the edge of the lubricant pocket induce a large area of backward escape of lubrication caused by microplasto hydrodynamic lubrication (MPHDL). On the other hand, when the radius on the edge is small MPHDL is impeded and microplasto hydrostatic lubrication appears instead implying forward escape of the lubricant. The occurrence of these mechanisms are quantitatively explained by a mathematical model combining a slab method of analysis of the strip drawing process and an analysis of lubricant escape by Reynolds equation.

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