Micropatterning of high-speed steel surface with femtosecond lasers: a comprehensive study on laser parameter effects

• Femtosecond laser can be used effectively for surface patterning on HSS steel. • Effects of laser parameters (power, frequency, energy, repetitions) were studied. • Typical geometry of the surface structure can be varied 0.9–100 µm. • Desired geometry can be obtained with an optimal parameter combination. Laser surface processing provides several benefits in engineering applications, such as non-contact operation, absence of tool wear, and rapid processing speed. Ultra-short pulse lasers enable the modification of surface patterns across a broad spectrum, from nanometres to micrometres, without inducing surface burn-in or heat-affected zones. This benefits various applications, including adhesion issues, wetting, and alterations in lubrication conditions, in ways unattainable through traditional machining techniques. Altering the laser parameters significantly modifies the laser-material interaction, leading to variations in the geometric attributes of the surface pattern. This benefit simultaneously constitutes a drawback of the method, as there are no pre-existing formulas for generating specific surface patterns. We employed a femtosecond laser to fabricate line geometries measuring several tens of micrometres on the surface of high-speed steel. The effect of laser power, frequency, energy, and scanning repetition and the influence of the geometric relationships of the resultant patterns are investigated. A collection of parameters appropriate for generating intricate surface patterns is also provided, contributing to surface machining without cracking, remelting, or extensive heat-affected zones.