Preliminary Studies of the Rapid Microwave Sintering of Green Parts Made of 420L Stainless Steel

Electromagnetic field distribution during microwave sintering ofmetal compacts, obtained by MIM or SLS was performed, evidencing afavourable necking stage promoted by local electric field concentrationamong the spherical particles. Microwave heating tests on 420L stainlesssteel cylindrical (20 mm diameter; 20 mm height) green parts obtained bySLS showed the possibility of achieving rapid sintering in single modeand multimode applicators operating at 2.45 GHz, in less than 20 minutes.The sintered parts, however, depending on the microwave heatingconditions, can present sensitisation due to the formation of chromiumcarbides, favoured by the C abundance provided by the decomposing organicbinder. This phenomenon constitutes a lower limit to the overall sinteringtime of the examined SLS green parts, which can be overcome only alteringthe sintering atmosphere or performing a preliminar de-binding ste