Laser boronizing of carbon steels with direct diode laser

Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050 °C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of carbon steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of FeB and Fe2B with thickness ranging 200-300µm thick. The laser boronizing process did not change the properties of the base material.