Abstract
KEYWORDS
hardening, build-up surfacing, testing, metallization, thermo spray, reconditioning, welding
ABSTRACT
The reconditioning procedure for auto vehicle parts has been an up-to-date field of research due to the numerous advantages that are generated by the use of reconditioned parts: significant savings concerning the raw materials, other materials, energy and labour; reduction of pollution during the reconditioning processes; utilization of a considerably large source of semi products resulted from the process of dismantling. One of the problem that has to be resolved is that the parts obtained by means of this reconditioning process should not only withstand heavy mechanical stress but also should be highly resistant to wear. The resistance to wear depends on the hardness of the metallic layers fixed during the reconditioning process on the surface of the part The hardness in its turn is directly determined by the properties of the added material. By the use of steels with a high content of carbon, an adequate value of hardness is obtained, but it is precisely this hardness that renders the processing of the metallic layers difficult and unproductive. At the same time, during the welding process, due to the heat transfer, structural changes occur and internal strains build up inside the part thus affecting the mechanical properties of the core of the processed part. The solution, experimented by the authors, consists in using low carbon steels during the welding process and enriching the carbon content of the superficial layers after the roughing operation has been completed. Finally, certain heat treatments and thermal and chemical treatments are applied in order to rebuild the core structure and to harden the surfaces of the reconditioned parts.