Effects of Interstitial Elements on the Fracture of Beta

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05650667
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Structural/Functional materials
• Research Institution: Kogakuin University
• Principal Investigator: NIWA Naotake Kogakuin Univ., Mechanical Eng., Professor, 工学部, 教授 (30011208)
• Co-Investigator(Kenkyū-buntansha): 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): 1993 – 1994
• Keywords: beta titanium alloys / fracture / hydrogen embrittlement / hydride / interstitial elements / beta phase / solubility / alpha phase

Research Abstract

This study aims to make clear the role of interstitial elements i.e.oxygen, nitrogen, carbon and hydrogen on beta titanium alloys. Content of oxygen, introgen and carbon of the alloys are determined by raw materials and atmosphere during melting, however, hydrogen is exceptional i.e.absorbed into the alloys during cold-working. This would be because beta phase has large hydrogen solubility. Hydrogen greatly suppresses the decomposition of metastable beta phase to alpha and beta phases. In general bata titanium alloys are not so sensitive to hydrogen embrittlement, for example, in the one of typical commercial beta titanium alloys Ti-15V-3Cr-3Sn-3Al, hydrogen embrittlement does not occur in the range of from 100ppm to 1000ppm hydrogen content. At the break point larger amount of hydrogen is measured in the alloy than in other alloys. It is probably because beta phase has large solubility of hydrogen.