Effects of nitrogen and high temperature aging on σ phase precipitation of duplex stainless steel

Effects of nitrogen and high temperature aging on σ phase precipitation of duplex stainless steels have been investigated. The precipitation of σ phase increases with the increase of aging time. The precipitation rate at 900 °C aging is the fastest and that at 700 °C aging is the lowest. The higher the aging temperature, the larger the size of σ phase precipitates. At the same condition, the more the nitrogen content, the lower the content of σ phase in duplex stainless steel.