| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lighweight Ti product free form rust, high in hardness and having a mother-of-pearl-like texture excellent in taste by subjecting a molding of a Ti alloy ofα-βphases orβphases to specified primary age hardening treatment, Ti crystal precipitating treatment, crystal precipitation density strengthening and secondary age hardening treatment in succession. SOLUTION: A rolling material of a Ti alloy ofα-βphases orβphases contg. >=70% metallic Ti is molded by mechanical working. This molding is subjected to primary age hardening treatment which holding at 350 to 600 deg.C for contain time in the air, in a vacuum or in an inert gas atmophere to increase its hardness to >=30 deg. HRC. Next, the molding is subjected to finish working such as grinding, polishing or the like as necessary and is thereafter subjected to crystal precipitating treatment of executing heating at 1000 to 1400 deg.C in a vacuum furnace to precipitate Ti crystals on the surface. The molding after this treatment is held at 350 to 600 deg.C for a certain time in a process of executing air-cooling in the air, in a vacuum or in an inert gas atmosphere to strengthen the precipitation density of the Ti crystals and is furthermore subjected to secondary age hardening treatment to increase its hardness to >=35 deg. HRC.
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