Laser Surface Coating-Texturing of Cold Roll with Hard Dimples

The surface texture of sheet steel plays an important role for automotive applications. To achieve appropriate surface topographies and press-forming behaviour, a new laser coating texturing (LCT) technique aimed at texturing steel work-rolls was proposed. The laser texturing process was realized by applying laser pulses at very high repetition rates to produce innumerable micro-craters with the required shape profile on the surface of the rolls. Moreover, the surface alloying of the dimples was carried out on the substrates of bearing steel GCr15. The submicron WC-Co alloy metal powder was melted into the micro-craters by high laser energy. The effects of processing parameters on the properties of the laser textured samples were investigated. The dimpled surfaces were examined by a 3-dimensional surface profilometer. Microstructures of the coating layers were assessed by optical and scanning electron microscopy. The experimental investigations show that the laser-dimpled hard-coated surfaces exhibit compatible metallurgical interfaces with the substrates. The laser coating textured roll is demonstrated to have excellent abrasion resistance and a much longer service life. The abrasive wear resistance was 5 times higher than that of the substrates. The average surface microhardness values were as high as 700HV.