Papers by Keyword: Layer Depth

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Authors: Bin Xu, Le Yang, Shi Bo Xing, Li Li
Abstract: In order to increase boronizing speed without decreasing the hardness of boride layer, the effect of plastic deformation at room temperature on powder RE-chrome-boronizing for a medium carbon steel (steel 45), in which boronizing plays a main role, was studied in this paper. The cold plastic deformation (CPD), whether compressing or shot-peening, can increase boronizing speed. Meanwhile, the boride layer can also retain its high microhardness (1 300―1 900HV0.1) with low brittleness. The layer depth achieved for a given heating time increases with increasing CPD degree on the steel. The analyses show that boronizing kinetics in the RE-chrome-boronizing (RE-Cr-B) samples with CPD can be enhanced.
Authors: Bin Xu, Ren Hong Guo, Zhong Quan Ma, Cai Gao, Xiao Hong Fan
Abstract: Effects of shot-peening on Cr-Rare earth-boronizing at 650°C for 4 – 8h for medium carbon steel are investigated in this paper. The value difference in boron diffusion activation energy between shot-peening and undeformation is calculated. The layer depth, microhardness and brittleness are also analyzed. The results show that the activation energy has a decrease of 5647.78 J/mol after shot-peening for 1.5h, and the layer depth increases with prolonged shot-peening time. The layer can also retain its high hardness with low brittleness. The analysis indicates that shot-peening can provide a large number of crystal lattice defects that facilitates boron diffusion in the steel, and the low temperature is apt to remain high dislocation density.
Authors: Fei Xie, Qiu Hua Zhu, Jin Jun Lu
Abstract: The influence of direct current field (DCF) on powder-pack boriding has been investigated by applying DCF between boriding agent and specimen during the soaking. Experimental results show that DCF has the function of heating the agent and the specimen and thus enhancing boriding. It is shown that the specimen’s side facing anode has the deepest boride case when the specimen is taken as cathode. It is proposed that DCF forces active boron-containing species to diffuse toward the specimen at the cathode. This makes boron concentration around the specimen as cathode higher than that at the anode or other position and that in the conventional powder-pack boriding (CPB), which relatively decreases boron’s absorption by inner wall surface of the pack box and the non-working surface of the specimen. DCF’s physical effect of enhancing chemical reaction in the agent increases the activity and concentration of active boron atoms and boron-containing species, which overcomes the shortcoming that CPB can not produce enough boron-containing species by conventional way of heating.
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