Abstract
The evolution of surface topography of 304L stainless steel, induced by long pulse laser with a wavelength of 1070 nm and a pulse width of 10 μs and a pulse number of 400 in air, was investigated in the fluence range between around 3 J/cm2 and 210 J/cm2. Three-dimensional (3D) morphologies and two-dimensional (2D) cross-sectional profiles of microstructures at different laser fluences were compared. Furthermore, surface profiles of the microstructures were quantified by using the inner diameter, the outer diameter, the elevation of central area and the rim height thereof. The trends of the above four geometrical parameters and surface profiles suggest five laser fluence ranges, where the corresponding topographies change from bump to crater. Energy dispersive spectrometer (EDS) was used to analyze surface elements of different microstructures, and the results showed that the content of oxygen had a great influence on surface tension and surface topography. In this study, a complex picture was drawn where melting, vaporization, solidification, melt displacement, melt expulsion and plasma shielding take place at different laser fluences.
Highlights
Surface texturing, which is a well-known method to produce microscale geometries and specific patterns on various types of materials, has been widely applied to improve material properties such as tribological, optical, biological and wetting characteristics for specific purposes.[1]
According to the surface topography and formation mechanisms, with the rise of laser energy the evolution of surface morphology of irradiated zone on 304L stainless steel surface can be divided into five phases which correspond to five laser fluence ranges
With the increase of laser fluence, the evolution of surface topography of irradiated zone on 304L stainless steel surface can be divided into five phases which correspond to five laser fluence ranges
Summary
Surface texturing, which is a well-known method to produce microscale geometries and specific patterns on various types of materials, has been widely applied to improve material properties such as tribological, optical, biological and wetting characteristics for specific purposes.[1]. As the most selected texture pattern of LST, various micro-dimples have been applied to improve friction behavior and wear performance as well as increase material service life,[4,5,6,7,12] reduce reflections and increase absorption for enhanced device performance,[8] enhance cellular adhesion to biomaterial surfaces[9,10] and change material wettability.[11,12] there are fewer researches on laser fabrication of micro-bumps, which as an important bionic texture are difficult to process. Du et al.[14] used a Nd:YAG pulsed laser with microsecond pulse duration to produce sombrero-shaped bumps with diameters of 230-250 μm and heights of 2-4 μm on steel GCr15 surface. Long pulsed laser was used to create spherical-cap-shaped domes with diameters of 30-70 μm and heights of 0.9-5.5 μm on 304L stainless steel.[15] Remarkably, there are few studies reported the laser fabrication of both bumps and
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
