On working and recrystallization of commercially pure titanium

• Published in: Journal of Japan Institute of Light Metals Vol. 7; no. 2; pp. 63 - 70
• Main Authors: MORINAGA, Takuichi, TAKAHASHI, Tsuneo, TAKAI, Tetsuya
• Format: Journal Article
• Language: Japanese; English
• Published: The Japan Institute of Light Metals 1957
• ISSN: 0451-5994; 1880-8018
• DOI: 10.2464/jilm.7.2_63

An investigation on the working and recrystallization of commercially pure titanium has been made chiefly by means of microscopic and X-ray method. The change of specific resistivity of titanium wires due to working and annealing was studied observing the coarse grain titanium specimens, in the course of heating with high ternperature microscope stage. Metallic titanium is readily deformed by twinning, but not all the grains of which the specimens consist. According to Dube and Alexander three types of twinning occur by cold rolling of titanium sheets, and in our investigation, at a certain reduction by rolling at least two of them occur in the same specimen. At 23% reduction by rolling of coarse grain specimen, second order twinnings are observed and above 40% reduction by rolling twins become strikingly fine. There seems no difference of hardness between twinned and not-twinned grains, however, sometimes the not-twinned grains show slightly higher hardness than the twinned. Changes are observed when heated the cold rolled coarse grain titanium sheet with high temperature microscope stage. Many newly recrystallized grains nucleated from the deformed coarse grains of titanium are recognized moreover, when heated up the specimen through trans-formation range the newly recrystallized grains become finer again, that is, the grains are refined by transformation in the course of heating. Contrary to our expectation, the recrystallization grains do not grow much even annealed at higher temperature. Electric specific resistivity is recovered almost under 400°C, and there are its minimum values between 500°-550°C. But, when annealed above 650°C the resistivity increases again remarkably. And, when annealed the titanium wires in air the resistivity increased rapidly between 30min-60min and then it tends to be saturated.