Materials & Design (Dec 2022)
Processability improvement of laser-assisted micro-machining 95W-3.5Ni-1.5Fe alloy based on surface and subsurface characteristics
Abstract
Laser-assisted micro-machining proves advantageous in improving the machinability of hard-brittle materials, but its effectiveness is easily weakened due to the uncertainty and complexity of microstructural transformation characteristics. In this research, a comprehensive investigation of the sustainable production mechanisms of tungsten heavy alloys was presented through recognizing the surface morphologies, subsurface microstructures, as well as micro-tool wear features, supported by the critical outcomes from single laser scanning (SLS) and laser-assisted micro-milling (LAMM) experimental tests. A laser thermal affected zone, which is composed mainly of surface oxide layer, near-surface softening layer, and subsurface metamorphic layer, was produced in laser heating. The relationship model between surface energy density and the thickness of laser thermal affected zone was determined. On this basis, a microstructure-based selection approach of the LAMM conditions, such as laser power and the depth of cut, was adopted to achieve a high-performance surface. Results indicated that a nanometer-level roughness surface, Sa = 57.03 nm, with no apparent residual thermal affected layer and newly generated subsurface damage layer were identified while suppressing flank wear. It is confirmed that the adaptability between the thickness of laser thermal affected layer and the depth of cut impacts LAMM sustainable production and justifies its application prospect.
