Diffusion Carbide Layers Produced on Tool Steel in Chromium Chloride Atmosphere at Low Pressure

Abstract

Diffusion chromizing of tool steel has been investigated, using a powder method modified by the use of low pressure during the process for the avoidance of the oxidation of the batch. Innovative chromizing novel processes have been carried out in a hot-wall vacuum oven. The processes have been performed in a chromium chloride atmosphere at a low pressure range from 1 to 800 hPa, with treatment temperatures of 850 to 950°C. Studies of layer thickness, its phase composition, and Cr, Fe, and C depth profiles in the diffusion zone of chromized layer have been conducted. The effect of the process parameters, such as time and temperature, on the growth kinetics of diffusion layers has also been investigated. A comparison was made between the layer thickness produced on the tool steel surface using the novel chromizing method, under low pressure, and a traditional chromizing process, by the pack powder method. Chromizing conducted at low pressure was found to be more effective for maximizing the growth rate of diffusion layers than that for chromizing by the traditional pack cementation method.