Plastic working of metallic glass bolts by cold thread rolling

Shigeru Yamanaka, Kenji Amiya, Yasunori Saotome, Akihisa Inoue

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Bolts are commonly employed machine elements used for joining and fastening, and their performance and reliability influence the overall performance of machines. In this study, we have plastically worked and formed bolts using metallic glass (MG) that exhibits unique mechanical properties such as high tensile strength, low Young's modulus, and large elastic limit. The large elastic limit increases the permissible elongation range of the bolt and helps avoid bolt loosening, while the low Young's modulus effectively resists screwed-in bolt loosening by increasing the frictional forces on both bolt-nut contact area and bearing surface. We employed a zirconium-based MG Zr 55Al10Cu30Ni5 for our experimental investigations. A pre-form of a hexagon socket head cap screw (bolt) was fabricated by squeeze casting. Cold and warm thread rolling were performed to form a metric screw thread M3×0.5 (class 6g (ISO)) below the glass transition temperature (7'g) using a flat rolling machine. Despite the extremely poor ductility of MG at room temperature, thread rolling was successfully performed. Straining behavior analysis by a three-dimensional finite element method demonstrated that these remarkable results are due to the compressive stress distribution induced during the thread rolling process. In addition, thread rolling is fundamentally an incremental process, and it enhances the deformability of MG by gradually improving ductility in the deformed region. The tensile strength of the thread-rolled bolt was approximately 1600MPa, which is considerably higher than that of conventional heat-treated high strength steel bolts. MG was thus successfully employed to manufacture improved bolts.

Original languageEnglish
Pages (from-to)243-249
Number of pages7
JournalMaterials Transactions
Volume52
Issue number2
DOIs
Publication statusPublished - 2011 Feb

Keywords

  • Metallic glass
  • Metallic glass bolt
  • Plastic working
  • Screw
  • Thread rolling

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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