Evolution of residual stress and damage in coated hard metal milling inserts over the complete tool life

Evolution of residual stress in Ti–Al–Ta–N coatings on hard metal milling inserts

“…Positon resolved residual stress measurements in the WC phase using laboratory X-ray sources and a special cover method did yield results similar to the ones from synchrotron measurements in this region of interest [10]. Details regarding the two compared test setups are described elsewhere [10]. At early stages of application, the residual stresses in the milling inserts are similar for both test setups: At the virgin state the residual stress state is compressive but within 1000 toolworkpiece contacts (also "cuts") it changed to a tensile state.…”

“…The influence of the chemical composition of the coating on the elastic constants such as Young's modulus E, Poisson ratio ν and X-ray elastic constant 1/2 s 2 in dependence of the crystallographic plane is discussed. These results shall illustrate the interaction of residual stresses with the observed damage states in [10] and [11] of the investigated milling inserts.…”

“…1) via position resolved synchrotron X-ray diffraction with high lateral resolution [9]. Positon resolved residual stress measurements in the WC phase using laboratory X-ray sources and a special cover method did yield results similar to the ones from synchrotron measurements in this region of interest [10]. Details regarding the two compared test setups are described elsewhere [10].…”

“…Details on machining parameters are described in [10] for both test setups. The same milling insert geometry and steel workpiece material were used in both test setups.…”

“…Upon the appearance of the first combcrack the detected tensile residual stresses decreased significantly in the WC phase in inserts, in which thermal Int. Journal of Refractory Metals and Hard Materials 52 (2015) 171-175 fatigue was dominant, whereas tensile residual stresses remained constant until the end of lifetime in the wear dominated test setup [10].…”