Corrosion behavior of low-temperature plasma carburized AISI 420 steel - part II - effect of treatment time
Cristiano José Scheuer1; Felipe Possoli2; Rodrigo Perito Cardoso3; Paulo César Borges2; Silvio Francisco Brunatto3
1 Universidade Federal de Santa Maria; 2 Universidade Tecnológica Federal do Paraná; 3 Universidade Federal do Paraná
doi:10.20906/CPS/CON-2016-0171
Resumo
The effect of plasma treatment parameters on the corrosion behavior of low-temperature carburized AISI 420 stainless steel was investigated by means of electrochemical measurements. The second part of this study (out of two), was conducted in order to evaluate the effect of the treatment time on carburized samples corrosion resistance. Plasma carburizing treatments were performed at 400°C (for times from 12 to 48 h) and 450°C (for times from 4 to 16 h). The corrosion behavior was evaluated through open circuit potential and cyclic polarization test, using a solution of 3.0% NaCl as electrolyte. To support the discussions on corrosion behavior, XRD, microstructural analysis, and hardness measurements were also carried out. The results showed that corrosion potential decreased with treatment times increased on the range of 12 to 48 h for treatments performed at 400 °C. For treatments realized at 450 °C corrosion potential increases from 4 to 8 h and decreasing subsequently for 12 and 16 h to. Furthermore, It was also found that long-term treatment (16 h for 450 °C and 48 h for 400 °C) showed smaller corrosion potential that the untreated sample. Finally, an analysis of the corroded surface showed the predominance of pitting corrosion mechanism on carburized samples, and widespread corrosion to the untreated sample.
Palavras-chave: low-temperature plasma carburizing; treatment parameters; martensitic stainless steel; expanded martensite; corrosion resistance; electrochemical tests