Effects of pre-strain and heat treatment temperature on phase transformation temperature and shape recovery stress of Ti-Ni-Nb shape memory alloys for pipe joint applications

Kazunari Uchida, Naoto Shigenaka, Toshio Sakuma, Yuji Sutou, Kiyoshi Yamauchi

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Effects of pre-strain and heat treatment on shape recovery stress and phase transformation temperature in Ti-Ni-Nb shape memory alloys with various Nb content (6. 9. and 12mol%) were investigated by tensile testing. The recovery stress of Ti-Ni-Nb alloys increased with increasing the pre-strain and then decreased after reaching the maximum recovery stress of around 450-500MPa at about 9% pre-strain. Martensitic transformation temperatures (Ms, As, Af) also increased with increasing the applied pre-strain. while the relation between As and pre-strain did not depend on the Nb contents and Ni/Ti ratio. Moreover, the recovery stress in the Ti-Ni-Nb alloy heat treated at 673 and 773 K after solution treatment was slightly higher than that in the solution-treated alloy. These behaviors were examined relative to the increased defect density due to pre-straining and the elimination of defects by heat treatment.

Original languageEnglish
Pages (from-to)1650-1655
Number of pages6
JournalMaterials Transactions
Volume49
Issue number7
DOIs
Publication statusPublished - 2008 Jul

Keywords

  • Pipe joint
  • Pre-deformation
  • Recovery stress
  • Shape memory alloy
  • Shape memory alloy (SMA) joint ring
  • Titanium-nickel-niobium alloy
  • Wide hysteresis transformation

ASJC Scopus subject areas

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

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