Abstract

The corrosion properties of duplex stainless steel type SAF 2205 after long-term ageing at 300°C and 400°C were investigated. However, these steels show a degradation of their properties as submitted by long time, in low temperatures about 280 to 520°C. This work describes this behavior by analysis of the resistance to general corrosion of the SAF 2205 steel ageing in the temperatures 300°C and 400°C, during 2000, 3000 and 5000 h, for sample aged at 400°C for 5000 h. The experimental techniques used were the potential dynamic curves (EPR-Double Loop), scanning and transmission electronic microscopy for microstructure analysis and weight loss test. It is verified that the ageing treatments modify the corrosion resistance due to microstructural changes of precipitation in the matrix and not by precipitation in grain boundaries (sensitization). However the sample aged at 400°C for 5000 h, due to the precipitation of phases G and α’, showed an appreciable increase in the loss of mass.

Key words: ageing, precipitation, corrosion, weight loss, EPR.