PRODUCTION OF INDUSTRIAL PURE TITANIUM FORGING STOCK EXCELLENT IN MECHANICAL STRENGTH

PURPOSE:To obtain a Ti structural material for a high-strength structural material which is capable of competing against a Ti alloy and has the order of 80kgf/m strength by performing the forging which is accompanied with upsetting by heating of beta phase region for an industrial pure Ti ingot contg. oxygen of a prescribed proportion and performing the finish forging of the low temp. warm region in alpha phase. CONSTITUTION:An industrial pure Ti ingot contg. 0.40-0.60wt% O2 content is firstly heated in the beta transformation point and above and the forging accompanied with the upsetting is repeatedly performed up to 600 deg.C temp. from the betaphase region together with grain refining due to the transformation and the macrostructure is sufficiently broken to attain grain refining. Then the Ti ingot after the above-mentioned forging treatment is reheated at about 800 deg.C of the low temp. region in the alpha phase and working in the nonrecrystallizing region is sufficiently performed up to 400 deg.C from this temp. to accumulate the transformation stress. Then this forging stock is subjected to the heat-treatment at 500-700 deg.C for