Aalco_Datasheet_St_St_Duplex

abc® Aalco is a registered trademark of Aalco Metals Ltd © Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with product form and product dimensions. For more complete details please refer to the relevant specification – The BS EN Specifications for Stainless Steel are listed on a separate Datasheet. Duplex Stainless Steel Duplex stainless steels are extremely corrosion resistant, work hardenable alloys. Their microstructures consist of a mixture of austenite and ferrite phases. As a result, duplex stainless steels display properties characteristic of both austenitic and ferritic stainless steels. This combination of properties can mean some compromise when compared with pure austenitic and pure ferritic grades. Duplex stainless steels are in most cases, tougher than ferritic stainless steels. Strengths of duplex stainless steels can in some cases be double that for austenitic stainless steels. Whilst duplex stainless steels are considered resistant to stress corrosion cracking, they are not as resistant to this form of attack as ferritic stainless steels. However, the corrosion resistance of the least resistant duplex stainless steels is greater than that for the most commonly used grades of stainless steels, i.e. 304 and 316. Duplex steels are also magnetic, a property that can be used to easily differentiate them from common austenitic grades of stainless. Property data given in this document is typical for flat rolled products covered by ASTM A240/A240M. ASTM, EN or other standards may cover products sold by Aalco. It is reasonable to expect specifications in these standards to be similar but not necessarily identical to those given in this datasheet. Applications Duplex stainless steels 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 Alloy Designations Due to excellent corrosion resistance and high strength, one of the most widely used duplex stainless steel in recent years has been 1.4462, also known as 2205. The name 2205 comes from a typical composition of 22% Chromium and 5% Nickel. There are many other duplex stainless steels such as 1.4507, 1.4410 & 1.4362 as well as proprietary grades developed by individual manufacturers such as LDX2101 from Outokumpu. Recently there has been a resurgence of interest in these ‘lean’ duplex grades as the high price of Nickel/Molybdenum means they can be price-competitive with austenitic grades. Euronorm UNS BS Grade 1.4462 S31803 S32205 318S13 2205 1.4507 S32520 S32550 - - LDX2101 Typical Chemical Compositions % 1.4462 1.4507 1.4410 LDX 2101 C 0.03 max 0.03 max 0.03 max 0.03 max Mn 2.0 1.5 1.5 5.0 Si 1.0 0.8 P 0.03 0.035 S 0.02 0.02 Cr 21-23 24-26 24-26 21.5 Mo 2.5-3.5 3.0-5.0 3.0 0.3 Ni 4.5-6.5 5.5-8.0 6 1.5 N 0.08- 0.2 0.2- 0.35 0.2 0.22 Cu - 0.5-3.0 0.5-3.0 abc® Aalco is a registered trademark of Aalco Metals Ltd © Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with product form and product dimensions. For more complete details please refer to the relevant specification – The BS EN Specifications for Stainless Steel are listed on a separate Datasheet. Typical Mechanical Properties Grade 1.4462 1.4507 2101 Tensile Strength (MPa) 620 770 675 Proof Stress 0.2% (MPa) 450 550 500 Elongation A5 (%) 25 25 30 Hardness Rockwell C 31 - Typical Physical Properties Property 2205 1.4507 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 Duplex stainless steels are extremely corrosion resistant. They have high resistance to intergranular corrosion. Even in chloride and sulphide environments, duplex stainless steels exhibit very high resistance to stress corrosion cracking. The super duplex grades are even more resistant to corrosion. Heat Resistance The high chromium content of duplex stainless steels that protects 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 Fabrication of all stainless steels 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 Duplex stainless steels 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 steels 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. abc® Aalco is a registered trademark of Aalco Metals Ltd © Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with product form and product dimensions. For more complete details please refer to the relevant specification – The BS EN Specifications for Stainless Steel are listed on a separate Datasheet. Welding Duplex stainless steels 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. Supplied Forms Aalco typically supplies 2205 duplex stainless steel in the following forms: ‹ Round bar ‹ CCP plate ‹ Quarto plate This information is based on our present knowledge and is given in good faith. However, no liability will be accepted by the Company is respect of any action taken by any third party in reliance thereon As the products detailed may be used for a wide variety of purposes and as the Company has no control over their use; the Company specifically excludes all conditions or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose. Any advice given by the Company to any third party is given for that party’s assistance only and without liability on the part of the Company. Any contract between the Company and a customer will be subject to the Company’s Conditions of Sale. The extent of the Company’s liabilities to any customer is clearly set out in those Conditions; a copy of which is available on request.