Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions

Y. Kaynak, B. Huang, H. E. Karaca, I. S. Jawahir

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish (Af) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

Original languageEnglish
Pages (from-to)3597-3606
Number of pages10
JournalJournal of Materials Engineering and Performance
Volume26
Issue number7
DOIs
StatePublished - Jul 1 2017

Bibliographical note

Publisher Copyright:
© 2017, ASM International.

Keywords

  • DSC analysis
  • NiTi shape memory alloy
  • XRD analysis
  • cryogenic machining
  • surface integrity

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering

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