The investigation of microstructure and mechanical properties of cementation steel boronized by pack boronizing method

The boronizing method, which is considered as one of the surface modification processes, improves the properties of the materials they serve in the service area and enables them to serve for a longer period of time. While boronizing increases the hardness, abrasion resistance and corrosion resistance on the surface of metals and alloys, it is also used to protect these properties at high temperatures and develops the property of the erosion resistance. Boron is generally used for the purpose of alloying or surface hardening in iron based materials. Mechanism of borinizing process; boron atoms diffuses to the metal surface under the influence of heat energy and form borides with the metal atoms. During boronizing method, the physical condition of the boron source can be solid, liquid or gas. The boronizing is usually carried out at 800-1100 ˚C for 1-12 hours. The filler material and de-oxidants keep out the oxygen during the boronizing process by creating a reducing environment. The method used during the boring process, the composition of material, the type of the material, the processing time and the process temperature are the factors affecting the obtained coating layer. The boride layers containing Fe2B and / or FeB phases are obtained with boronizing on the surface of the steel material at high temperatures. The hardness and abrasion resistance of the layers obtained by boron diffusion in steel can be increased significantly. In this study, the cementation steel was carried out at 850, 950 and 1050 ºC for 6, 8 and 10 hours. The microstructure change on the surface of the samples after the boronizing process was investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-Ray diffraction analysis (XRD), elementel mapping analysis and electron backscatter diffraction (EBSD). Sawtooth morphology of all the samples were observed in the coatings and surface roughness, microhardness and layer thicknesses were measured separately for each sample.