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

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

JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE, cilt.26, ss.3597-3606, 2017 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 26
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1007/s11665-017-2791-7
  • Dergi Adı: JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.3597-3606
  • Anahtar Kelimeler: cryogenic machining, DSC analysis, NiTi shape memory alloy, surface integrity, XRD analysis, INDUCED MARTENSITE STABILIZATION, TRANSFORMATION BEHAVIOR, ROOM-TEMPERATURE, TOOL-WEAR, DEFORMATION, DRY, MICROSTRUCTURE, INTEGRITY, PHASE, REORIENTATION
  • Marmara Üniversitesi Adresli: Evet

Özet

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.