The basic properties of the duplex stainless steel
- Duplex stainless steel is a kind of steel grade that contains both austenitic and ferritic organizational structure. Furthermore, the two phase organizations should exist independently, with a large content. It is generally considered that the minimum phase content should be more than 15%. In the actual application, routinely called as α十γ Duplex stainless steel or just Duplex stainless steel, the Austenitic & Ferrite Duplex stainless steel takes Austenitic as the main ingredients which is usually not less than 30%. The most common situation is two phase each accounts for about 50%.
Having the duplex structure of α十γ, Duplex stainless steel have the feature of both Austenitic stainless steel and Ferritic stainless steel. Compared wtih Ferritic stainless steel, the Duplex stainless steel has higher toughness and lower brittle transition temperature. Besides, the intergranular corrosion resistance and welding performance of Duplex stainless steel were significantly improved. Furthermore, it remains some feature of Ferritic stainless steel, such as such as 475 ℃ brittleness, high coefficient of thermal conductivity, small linear expansion coefficient, having super plastic, magnetic, etc. When compared with Austenitic, Duplex stainless steel has higher intensity. Specially the yield strength is increased significantly and the resistance of intergranular corrosion and stress corrosion as well as corrosion fatigue resistance performance will be improved at the same time.
The content of alloy elements directly affects the phase ratio and other related performance of Duplex stainless steel. Ni is used to adjust the duplex stainless steel to have a reasonable proportion. N is an element of austenite forming. At a high temperature, the ability of N to stabilize austenite is greater than that of Ni. Also, N can improve the performance of resistance to pitting corrosion and crevice corrosion. In the steel, Cr is a forming element of ferritic, insure a reasonable phase proportion. With the content of Cr increasing, the stain resistance of Duplex stainless steel wil be improved gradually. As another element of ferritic forming, Mo, as well as W, can improve the performance of resistance to pitting corrosion and crevice corrosion. However, it will increase the brittleness of steel when the content of Mo is great. Besides, Cu has an ability to improve the corrosion resistance of steel in the reducing medium. - 【Hits:】 【Add:2013-03-12】 【Close】
