Due to the wide-range use of low cost and high performance laser sources, laser surface hardening (LSH) process has arisen as an powerful method for improving the mechanical properties of a large variety of metallic materials. LSH has been studied in the past regarding its influence on stress and wear behavior. In particular, the procedure is used to fabricate wear-resistant molds for forming applications in the automotive industry. In addition, other functionalities can be added to the mold surface after providing a geometrically defined surface microstructures in order to further reduce friction and/or wear which leads to an improvement of tool lifecycle. These structured surfaces can be produced using laser-based manufacturing methods. 

In this study, the influence of laser hardening on the quality and homogeneity of the fabricated structures using direct laser interference patterning (DLIP) method is investigated. For the fabrication of the DLIP structures a 7 ns laser source with a wavelength of 1064 nm is used to fabricate line-like structures with a spatial periods of 6.0 µm and 15.0 µm on Steel (40CrMnMo7) and cast iron (EN-GJS-HB265) samples. Hardening was performed with an infrared continuous wave diode laser at a temperature of 1200 °C. In the treated area, a coarse martensite with residual austenite structure was observed, resulting in a wear resistant effective layer of 1.4 mm with a surface hardness of 740 HV for steel and 0.9 mm for cast iron with a surface hardness of 935 HV. Besides reducing the contact area between the forming tool and the metal sheet and improving the lubrication of the system using the microstructures, the laser hardening of the DLIP structures could increase the service life of the forming tools.