Influence of XHV-adequate atmosphere on surface integrity

Abstract

In aerospace engineering, high temperature alloys such as titanium are the preferred choice. However, machining of such materials remains a major challenge due to high process forces and process temperatures. Currently, machining is performed almost entirely in the presence of oxygen. This results in a process-inherent oxidation of the metal surface, which leads to higher tool wear during machining. By means of an oxygen-free machining undesirable oxidation reactions will be avoided and thus results in an extension of tool life. In addition, oxygen-free machining in an extreme high vacuum (XHV) adequate environment can influence the resulting workpiece surface and subsurface properties due to change in process forces and chip formation. In the present work, the influence of machining under air and XHV-adequate atmosphere is examined with regard to chip formation, workpiece surface topography and residual stresses. Significant differences can be seen in resulting surface integrity depending on the machining atmosphere.

Oxygen‐Free Production—From Vision to Application

“…The core roughness of machined specimens determined from Abbott curves is reduced by around 25% and residual stress fluctuations in circumferential direction of a longitudinally turned specimen seem to be reduced in oxygen-free atmosphere compared to air. [73] In general, cutting in oxygen-free atmosphere has a strong influence on process, component behavior, and component surface properties of Ti-6Al-4V.…”

“…Prasanthan et al analyzed chip formation and surface properties of Ti–6Al–4V components machined by longitudinal turning at a cutting speed of 60 m min −1 . [ 73 ] They found lengthened strip chips in air and curled chips in oxygen‐free environment. The approximately 15% smaller chip thickness in air hints toward a change in chip formation mechanism.…”

“…The core roughness of machined specimens determined from Abbott curves is reduced by around 25% and residual stress fluctuations in circumferential direction of a longitudinally turned specimen seem to be reduced in oxygen‐free atmosphere compared to air. [ 73 ]…”