The Performance Study about the Boronitriding Layer in the Low Temperature

The experimental results showed that the layer is composed of boride zones and transition zones. Boride zones are dense and there are not porosities and micro-crack. The boride zones of carbon steel appear tine-comb by low-temperature boronitriding and consist FeB+Fe2B. The boride zones of alloyed steel appear flat, and their phase constitution are compLicated. The phase constitution of the surface of Cr12 steel by low-temperature boronitriding are Fe2B, FeB and Fe4N. The phase constitution of sub-surface are FeB, Fe2B, Fe3(C, B), (Fe, Cr)2B, Fe4N and Fe3C. There are Fe3(C, B), Fe4N, etal in transition zone, and this get strengthening and tightly adhere to boride. It indicates that the morphology and brittleness of boride are improved and the depth of boronizing layer is deeper by adding RE. The results of micro-hardness test showed that surface hardness has a highest value in the boride, it is 1780HV. The micro-hardness profile low-temperature boronitriding layer of carbon steel from surface to core is more smoothing. The micro-hardness profile low-temperature boronitriding layer of alloyed steel is steep. There is not softened zone in transition zone compared with high-temperature boronitriding, which benefit to binding of the layer and matrix.