Diffusion bonding at solid state of graphite spheroidal cast iron 38-15

Author.Diffusion bonding at solid state under pressure allows one to join materials which are difficult to bong together with classical techniques. This difficulty is due essentially to the thermally affected areas during or after using fusion bonding. The experiments which have been carried out during solid state diffusion bonding of graphite spheroidal cast iron have shown that it is in fact possible to obtain acceptable junction. This consists of using a laboratory conceived apparatus which allow us to exert a given controlled pressure on samples to be welded inside a heated container. This work was especially focused on the optimization of the various operating conditions, namely: the applied stress, temperature and the reaction time. A good quality was obtained with the following parameters: times 15 mn, temperature 900 degree celsius, surfaces with a low roughness and applied stress, equal to 12.5 Mpa. Metallographical observations on bonded samples exhibit a continuity of the ferritic-perlitic structure on the level of the interface. The traction test carried out on welded specimen exhibit a resistance to fracture of around 80 % of the base metal value. Fracture surface observed by means of scanning electronic microscopy, revealed that the fracture zones are generally located in the middle of the samples which means continuity in the material, and a good adhesion