High-strength and high-ductility mechanism of pure Ti sintered material using hydrogen and oxygen

2015 Fiscal Year Final Research Report

• Project/Area Number: 25249102
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Material processing/Microstructural control engineering
• Research Institution: Osaka University
• Principal Investigator: Kondoh Katsuyoshi 大阪大学, 接合科学研究所, 教授 (50345138)
• Co-Investigator(Kenkyū-buntansha): UMEDA JUNKO 大阪大学, 接合科学研究所, 助教 (50345162) ; SUNADA SATOSHI 富山大学, 工学部, 教授 (00206575) ; SASASE MASATO 若狭湾エネルギー研究センター, 研究員 (60359239)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 粉末冶金 / 純チタン / 相変態 / 残留水素 / 加工熱処理 / 集合組識 / 変形双晶 / ヤング率

Outline of Final Research Achievements

To clarify high-strength and ductility mechanism of pure Ti material with small additive hydrogen, TiH2 raw powder was consolidated by sintering and hot extrusion. The residual hydrogen content depended on the sintering temperature, and affected on α/β phase transformation during extrusion. In case of 0.33 mass% hydrogen content, α→β phase transformation completely occurred at 1073 K, and resulted in <0001>α texture formation of extruded Ti material. This texture was never observed in the conventional extruded Ti materials (<10-10>α texture) with few hydrogen elements. The former indicated high tensile strength (σ) of 959 MPa and elongation (δ) of 27.6% compared to PM pure Ti materials with σ=634 MPa and δ=29.9%. In-situ SEM observation on the hydride dispersoids in PM Ti material indicated that they could be obviously deformed in tensile and had a ductile property at room temperature.

Free Research Field

粉末冶金