Microstructure Control for Attaining Over 2Gpa of Tensile Strength in Beta Titanium Alloys

1991 Fiscal Year Final Research Report Summary

• Project/Area Number: 02650512
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 金属材料(含表面処理・腐食防食)
• Research Institution: The University of Tokyo
• Principal Investigator: NIWA Naotake The University of Tokyo, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30011208)
• Co-Investigator(Kenkyū-buntansha): ONO Katsuo The University of Tokyo, Faculty of Engineering, Research Associate, 工学部, 助手 (20160905) ; TUNAKAWA Hideo The University of Tokyo, Faculty of Engineering, Research Associate, 工学部, 助手 (90107558) ; KISHI Teruo The University of Tokyo, Rcast, Professor, 先端科学技術研究センター, 教授 (40011085)
• Project Period (FY): 1990 – 1991
• Keywords: titanium alloy / beta titanium alloy / Ti-15V-3CR-3Sn-3Al / Cold-working / aging / mechanical property / duplex-aging / 冷間加工

Research Abstract

The features of the beta titanium alloy Include Its superior cold-formability in the solution-treated state and Its Increased strength after undergoing subsequent aging-treatment. Consequently, the method of aging after cold-forming Is a heat-treatment method which utilizes the features of the beta titanium alloy. The heat-treatment method of aging after cold-working is known to remarkably promote the aging response and fine precipitation of alpha phase in commercial beta titanium alloy. It was reported that, compared with the method of aging without cold-working after solution-treatment, this heat-treatment method Improved the balance between strength and ductility of commercial beta titanium alloy Ti-, 13-llCr-3Al, however, It was considered, - that this heat treatment method reduced ductility while aiming to achieve high strength and that the strength-ductility balance could not be Improved for commercial beta titanium alloy Ti-15V-3Cr-3Sn-3Al. Mechanical properties were studied by tensile test of Ti-15V-3Cr-3Sn-3AI alloy obtained by duplex-aging after cold-swaging, i. e. aging at high temperatures followed by re-aging at a lower temperature. Combinations of short-time aging at 823K, 873K and 923K and re-aging at 673K have greatly Improved the strength-ductility balance of this alloy, realizing high strength with adequate tensile elongation. This duplex-aging process further diminishes the Influence of reduction of cold-swaging on the mechanical properties after aging.