Picosecond laser pulse polishing of ASP23 steel

•Roughness of ASP23 with 0.22 μm can be polished to 0.158 μm.•Spatial frequency of polished surface in a direction perpendicular to grinding marks is reduced.•Microstructures of melt and heat affected zones are martensite, tempered martensite, carbides; and dendrite. Picosecond laser pulses, in laser polishing, induce a light-material interaction in an extremely short period of time to melt steel. The generated heat affected zones (HAZ) are almost negligible. The induced thermal distortion of the polished workpieces can be reduced notably. This paper shows a kind of powder-metallurgical steel, ASP23, polished by a picosecond laser. The purpose of this research is to reduce thermal distortion of the workpieces after laser polishing. The surface morphologies and roughness of the polished surfaces are shown as well. Fourier analysis is used to analyze the surfaces of polished materials. In addition, the microstructure of polished ASP23 surfaces is examined.