材料期刊网

The effects of phase transformation on mechanical properties and pitting corrosion of 2205 duplex stainless steel have been investigated. The amount of σ phase in the test specimen was varied up to a maximum of 6% by thermal treatment at 850°C for period of time of up to 60 min. The results showed that σ phase both markedly increased the hardness and decreased the impact toughness of the test steel. But the increasing tendencies of the ultimate tensile strength and the yield strength were not obviously, while the total elongation abruptly decreased with the aging time from 5 min →15 min →60 min. SEM impact microfracturegraphs analysis revealed that the types of impact fracture changed from ductile mode to transcrystalline mode when the specimens aged from 5 min to 60 min. Furthermore, the extent of pitting potential reducing was found to be strongly temperature dependent, being more pronounced at the higher temperature. During the incubation period of σ phase nucleation, the pitting corrosion test temperature and the aging time had collaborative effects on evidently displacing the pitting potential towards less noble values. After 15 min, the higher temperature contributed more on decreasing the pitting potential than the aging time did.