Ref.: MmeCo43-001
Apresentador: Pedro Victorio Caetano Abrantes Quadros
Autores (Instituição): Quadros, P.C.(Universidade Tecnológica Federal do Paraná); Berton, E.M.(Centro Universitário de Tecnologia de Curitiba); Borges, P.C.(Universidade Tecnológica Federal do Paraná);
Resumo:
The Solution Heat Treatment after Plasma Nitriding (SHTPN), followed by requenching and tempering has been studied to increase the hardness of the ferritic stainless steel AISI 409 without compromising its corrosion resistance. This treatment consists of material plasma nitriding, followed by the solution and oil quenching, resulting in the dissolution of nitrides and the formation of a nitrogen martensitic layer. Requenching aims the microstructure refinement, and tempering has the objective of residual stress relief. This work aims to compare the nitrogen martensitic layer of AISI 409 steel treated by SHTPN, requenching (1050°C), and tempering (250, 350, 450, and 650°C) with the carbon martensite of AISI 420 martensitic stainless steel quenched and tempered in the same temperatures. Optical microscopy was utilized to evaluate the microstructures, Vickers microhardness was applied to characterize the superficial hardness and DL-EPR was used to analyze the intergranular corrosion and determine the degree of sensitization. Results have shown the formation of a nitrogen martensitic layer with a thickness above 750µm on AISI 409 steel. A proportional decrease in hardness was verified with the increase of tempering temperature for both materials, whereas AISI 420 steel showed a higher superficial hardness. Carbon martensite had a higher degree of sensitization on the 250°C tempered sample, compared with the same temperature investigated for AISI 409 steel. In contrast, the nitrogen martensitic layer showed a higher intergranular corrosion susceptibility on tempered conditions at 350, 450, and 650°C. So, the more favorable result was observed for the condition of tempering at 250°C for the AISI 409 steel.