| 摘要 |
PROBLEM TO BE SOLVED: To stably and surely obtain the material in which any irregular surface polishing marks are inhibited from being generated by specifying thickness of the material and the hardness distribution of its surface that is polished and finished to have a specified roughness. SOLUTION: The thickness of the material is adjusted to 4 to 30mm and in the surface of the material, that is polished and finished so as to have a <=0.3μm average roughness (Ra), the maximum and minimum of Vickers hardness measured values with a <=1kg load at positions of points of >=10, which are selected at intervals of 0.3 to 1mm in an arbitrary direction on the surface are adjusted to <=10. The titanium material having this hardness distribution is obtained by cooling it at an about >=1,000 deg.C/hr cooling rate so as to pass the temp. through theβ-transformation point in the process from the casting of a molten titanium material into an ingot to the forming of the ingot into a platelike or ringlike shape and thereafter, performing working treatment, etc., of the resulting formed material in a temp. region lower than theβ-transformation point. Thus, the objective titanium material in which even very slight visual irregular polishing marks such as simple bright and dark marks are inhibited from being generated can be obtained.
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