Surface topography and subsurface integrity of titanium grade 2 machined by nanosecond laser: the effects of scanning speed, laser power, and frequency

Abstract

Surface quality is a major requirement in industrial level for every mechanical part, as it can define not only their ability to be appropriately used in assemblies but also their service life. Nowadays, the increased capabilities of modern measurement equipment have allowed the study of more advanced parameters such as the uniformity of texture or functional parameters of the roughness profile, which can lead to reliable conclusions about tribological and lubrication properties of machined surfaces as well. In the present case, a thorough investigation of surface topography and texture was carried out for the case of laser engraving of square pockets on a titanium alloy workpiece under diverse process conditions. Analysis of the results revealed that apart from the high correlation of laser power and laser scanning speed with amplitude parameters of surface roughness, laser engraving can have a profound effect on directionality of the produced texture, with higher speeds and moderate VED values leading to less isotropic surfaces. Moreover, although based on the analysis of Ssk and Sku values, which were found to be mostly positive and below 4 respectively, most surfaces exhibit high peaks and reduced fluid retention capability, the latter can be increased by appropriately selecting the combination of process conditions during laser engraving process.