Residual stresses formation after re-contouring of welded Ti-6Al-4V parts by means of 5-axis ball nose end milling

The major step of the process chain for regeneration of damaged components is the removal of excess weld material, called re-contouring. This material removal process influences the surface integrity and therefore the functional performance of components. But today the surface integrity, e.g. residual stresses, cannot be predicted to a satisfying degree due to the complex physical effects during the cutting process. This paper investigates the fundamental influence of cutting conditions, tool geometry and weld characteristics on the residual stress formation after 5-axis ball nose end milling of Ti-6Al-4V. It is shown experimentally, that the cutting edge radius is the most influencing factor on residual stresses. Furthermore it is shown, that the thermal effects during cutting have a minor influence on the residual stresses due to the properties of titanium and the ball nose end milling process. Finally a basic physical approach is given to explain the effects by considering only the uncut chip volume, which is generating the final surface. (C) 2014 CIRP.Titanium