Mechanical Properties of Duplex stainless steel Table 3. Typical mechanical properties of two duplex stainless steel alloys | Grade | 2205 | UR52N+ | | Tensile Strength (MPa) | 620 | 770 | | Proof Stress 0.2% (MPa) | 450 | 550 | | Elongation A5 (%) | 25 | 25 | | Hardness Rockwell C | 31 | - | Physical Properties of Duplex stainless steel Table 4. Typical mechanical properties of two duplex stainless steel alloys | Property | 2205 | UR52N+ | | Density (g.cm3) | 7.805 | 7.810 | | Modulus of Elasticity (GPa) | 200 | 205 | | Electrical Resistivity (Ω.m) | 0.085x10-6 | 0.085x10-6 | | Thermal Conductivity (W/m.K) | 19 at 100°C | 17 at 100°C | | Thermal Expansion (m/m.K) | 13.7x10-6 to 100°C | 13.5x10-6 to 200°C | Corrosion Resistance of Duplex stainless steel Duplex stainless steelare extremely corrosion resistant. They have high resistance to intergranular corrosion. Even in chloride and sulphide environments, Duplex stainless steel exhibit very high resistance to stress corrosion cracking. The super duplex grades are even more resistant to corrosion. Heat Resistance of Duplex stainless steel The high chromium content of Duplex stainless steel that p rotects against corrosion, causes embrittlement at temperatures over about 300°C. At low temperatures duplex stainless steels have better ductility than the ferritic and martensitic grades. Duplex grades can readily be used down to at least -50°C.
Fabrication of Duplex stainless steel Fabrication of all stainless steel should be done only with tools dedicated to stainless steel materials. Tooling and work surfaces must be thoroughly cleaned before use. These precautions are necessary to avoid cross contamination of stainless steel by easily corroded metals that may discolour the surface of the fabricated product. Heat Treatment of Duplex stainless steel Duplex stainless steel cannot be hardened by heat treatment. They can however be work hardened. Solution treatment or annealing can be done by rapid cooling after heating to around 1100°C. Machinability Although machinable, the high strengths of Duplex stainless steel makes machining difficult. As an example, machining of 2205 is around 20% slower than for 304. Machining can be enhanced by using the following rules: · Cutting edges must be kept sharp. Dull edges cause excess work hardening. · Cuts should be light but deep enough to prevent work hardening by riding on the surface of the material. · Chip breakers should be employed to assist in ensuring swarf remains clear of the work · Low thermal conductivity of austenitic alloys results in heat concentrating at the cutting edges. This means coolants and lubricants are necessary and must be used in large quantities. Welding of Duplex stainless steel Duplex stainless steel have good weldability. All standard welding processes can be used. They are not quite as easily welded as the austenitic grades but low thermal expansion in duplex grades reduces distortion and residual stresses after welding. The recommended filler material for 2205 stainless steel is 2209. Applications of Duplex stainless steel Duplex stainless steel are typically used in: · Chemical processing, transport and storage · Oil and gas exploration and offshore rigs · Oil and gas refining · Marine environments · Pollution control equipment · Pulp & paper manufacturing · Chemical process plant Supplied Forms Aalco typically supplies 2205 duplex stainless steel in the following forms: · Round bar · CCP plate · Quarto plate | 
Aalco - Ferrous and Non-Ferrous Metals Stockist
