Research on Properties of Fe-Based Powder Metallurgy Material Strengthened by Boriding

The pack boriding process of Fe-based powder compact was carried out at 850 to 1050°C for 3 to 10 h. The microstructure and the thickness of the boride layer were observed by VHX-6000 ultra-depth microscopic three-dimensional microscope. The surface hardness of the boride layer was measured by a Rockwell hardness tester, the phase composition of the boride layer was analyzed by X-ray diffractometer and the friction and wear properties of the sample were tested on the MMW-2 friction and wear tester. The worn surfaces of boride layer was observed by scanning electron microscope. The results show that the boride layer was mainly composed of Fe2B single phase, and its thickness was uniform and firmly bonded to the substrate. The thickness and hardness of the layer gradually increased with time and temperature. The binding force between the layer and the substrate would be decreased while the thickness of the layer was too thin or too thick. Boriding at 850, 900, and 950°C resulted with formation of Fe2B phase while FeB and Fe2B phases occurred at 1050°C. The thickness of the layer in a suitable range could improve the wear properties of the material.