A. K. Rit, P. Shanmugam, R. Natarajan, Tube Investments Of India Limited, Chennai, India
Vacuum heat treatment process has got a world wide acceptance as an alternative to atmosphere heat treatment process. There is a tremendous increase in use of vacuum heat treating in last decade because of reduced distortion and clean product obtained from this process. In this paper, vacuum carbo-nitriding with high pressure gas quenching for heat treating smaller parts like “stepped bush” is explored. The bush is made out of SAE5120. A comparison between Batch integral quench furnace and vacuum furnace for heat treating smaller parts are discussed. Metallurgical and physical aspects of the heat treated products are analyzed and found that vacuum furnace has shown better results. Inter granular oxidation is absent in vacuum heat-treated products in this investigation. Distortion analysis is carried out on these heat treated products for the two furnaces. The merits and drawbacks between these two heat treatment furnaces for heat-treating smaller parts are discussed in this paper.
Summary: Vacuum heat treatment process is widely accepted because of reduced distortion and clean product obtained from it.In this paper vacuum carbonitriding with high pressure gas quenching is used for heat treating steeped bush-A component used for chain making.Same experiment was conducted with batch integral quench furnace and comparison was made between these two furnaces.Distortion analysis was done using standard Navy 'C'ring for both furnaces.Results show vacuum furnace is better in terms of metallurgical aspects.Inter granular oxidation is absent in vacuum heat treating.Also the product obtained is clean and easy to handle.
