Machining-induced surface integrity in titanium alloy Ti-6Al-4V: An investigation of cutting edge radius and cooling/lubricating strategies

Guang Chen, James Caudill, Shi Chen, I. S. Jawahir

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Enhanced surface integrity can increase the service life and functional performance in machined components, including the strength and fatigue life of machined parts. To study the influence of cutting edge radii and cooling/lubricating conditions on surface integrity, in this work variable cutting edge radii (less than 5 μm, 28 μm and 50 μm) and a range of cooling/lubrication conditions (Dry, MQL, LN2, Hybrid with LN2 and MQL) were applied in orthogonal cutting of Ti-6Al-4V alloy. Experimental analysis revealed that ploughing effects, which increase with increasing cutting-edge radii, and result in material being compressed into the machined surface, lead to an increase in thrust force, drive the evolution of subsurface microstructure at the cross-section which is normal to the direction of cutting speed. No obvious grain refinement layer was observed while utilizing the sharp cutting edge (<5 μm). At larger edge radii (28 and 50 μm), the thickness of grain refinement layer caused by severe plastic deformation (SPD) increased significantly. The residual stresses analysis was carried out based on investigations of selected experimental conditions. In machining with larger cutting edge radii and hybrid cooling, significant increases in the magnitude and depth of machining-induced compressive residual stress fields were also observed. Additionally, surface hardness also increased slightly with increasing cutting edge radius. Machining with cryogenic cooling (LN2) generated thinner deformation layers and larger deformation gradients, due to higher deformation stress and lower fracture strain at lower temperature conditions. Moreover, the rapid transfer heat from the cutting zone mitigated the tensile stress generating mechanisms, typically associated machining, allowing for mechanical ploughing effects to become dominant in the near-surface region of the machined workpieces.

Original languageEnglish
Pages (from-to)353-364
Number of pages12
JournalJournal of Manufacturing Processes
StatePublished - Feb 2022

Bibliographical note

Publisher Copyright:
© 2021 The Society of Manufacturing Engineers


  • Cryogenic cooling
  • Cutting edge radius
  • Ploughing effect
  • Residual stresses
  • Surface integrity
  • Ti-6Al-4V alloy

ASJC Scopus subject areas

  • Strategy and Management
  • Management Science and Operations Research
  • Industrial and Manufacturing Engineering


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