Austenitic, Cr-Ni-Mo Alloyed Stainless Steel Grades

Standard Cr-Ni-MoStainless SteelsCharacteristic properties• All-purpose grades• Enhanced corrosion resistance compared to standard Cr-Ni grades• Excellent formability• Excellent weldability• Excellent impact strengthSteel gradesOutokumpu EN ASTM4401 1.4401 3164404 1.4404 316L4436 1.4436 3164432 1.4432 316L4406 1.4406 316LN4429 1.4429 S316534571 1.4571 316Ti4435 1.4435 316LOutokumpu International Typical composition, % National steel designations, steel name steel no. superseded by EN EN ASTM C N Cr Ni Mo Others BS DIN NF SS 4401 1.4401 316 0.04 – 17.2 10.2 2.1 – 316S31 1.4401 Z7 CND 17-11-022 2347 4404 1.4404 316L 0.02 – 17.2 10.1 2.1 – 316S11 1.4404 Z3 CND 17-11-02 2348 4436 1.4436 316 0.04 – 16.9 10.7 2.6 – 316S33 1.4436 Z7 CND 18-12-03 2343 4432 1.4432 316L 0.02 – 16.9 10.7 2.6 – 316S13 – Z3 CND 17-12-03 2353 4406 1.4406 316LN 0.02 0.14 17.2 10.3 2.1 – 316S61 1.4406 Z3 CND 17-11 Az – 4429 1.4429 S31653 0.02 0.14 17.3 12.5 2.6 – 316S63 1.4429 Z3 CND 17-12 Az 2375 4571 1.4571 316Ti 0.04 – 16.8 10.9 2.1 Ti 320S31 1.4571 Z6 CNDT 17-12 2350 4435 1.4435 316L 0.02 – 17.3 12.6 2.6 – 316S13 1.4435 Z3 CND 18-14-03 2353 4301 1.4301 304 0.04 – 18.1 8.3 – – 304S31 1.4301 Z7 CN 18-09 2333 904L 1.4539 904L 0.01 – 20 25 4.3 1.5 Cu 904S13 1.4539 Z2 NCDU 25-20 2562 254 SMO® 1.4547 S31254 0.01 0.20 20 18 6.1 Cu – 1.4547 – 2378 LDX 2101® 1.4162 S32101 0.03 0.22 21.5 1.5 0.3 5 Mn – – – – 2304 1.4362 S32304 0.02 0.10 23 4.8 0.3 – – 1.4362 Z3 CN 23-04 Az 2327 2205 1.4462 S32205* 0.02 0.17 22 5.7 3.1 – 318S13 1.4462 Z3 CND 22-05 Az 2377Chemical composition Table 1General characteristicsThese grades are molybdenum-containing austenitic stain-less steels intended to provide improved corrosion resistance relative to the standard Cr-Ni steel grades used in corrosive process environments.The addition of molybdenum provides improved resistance to pitting and crevice corrosion in environments containing chlorides or other halides.These grades are used in applications for handling the wide range of chemicals used by process industries, e.g. pulp and paper, textile, food and beverages, pharmaceutical, medical, and in the manufacture of other chemical processing equip-ment. These grades are supplied with a wide range of func-tional and aesthetic surfaces.Modern stainless steels are today eisaly produced with low carbon contents and the risk of chromium carbide precipita-tion has thereby decreased significantly. Intergranular corro-sion caused by chromium carbides is therfore rarely an issue nowdays, but stabilised grades, often type 1.4571, are still specified. Non-titanium-stabilised grades generally have a better surface finish than titanium-stabilised grades.Given their fully austenitic structure, all these grades are non-magnetic in the annealed condition but may become slightly magnetic as a result of phase transformation due to cold working or welding. The high nitrogen grades, i.e. 1.4406 and 1.4429 have except from an increased mechani-cal strength also a more stable austenitic structure leading to a lower permeability in comparison to the other standard Cr-Ni-Mo stainless steel grades.* Also available as S31803Chemical compositionThe chemical composition of specific steel grades may vary slightly between different national standards.The required standard will be fully met as specified on the order.Outokumpu Stainless2 Standard Cr-Ni-Mo Stainless SteelsMechanical properties. Hot rolled plate/cold rolled strip and sheet, minimum values at 20°C Table 2Mechanical propertiesOutokumpu Stainless uses the European Standard EN10088 where applicable. The permitted design values may vary between product forms, see the specification in question for the correct value. Steel grade Proof strength Tensile strength Elongation Impact value Rp0.2 Rp1.0 Rm A5 KV MPa MPa MPa % J4401 220/240 260/270 520/530 45/40 604404 220/240 260/270 520/530 45/40 604436 220/240 260/270 530/550 40/40 604432 220/240 260/270 520/550 45/40 604406 280/300 320/330 580/580 40/40 604429 280/300 320/330 580/580 40/35 604571 220/240 260/270 520/540 40/40 604435 220/240 260/270 520/550 45/40 60The values in Table 2 and 3 refer to hot rolled plate/cold rolled strip and sheet. For hot rolled strip, the proof strength corresponds to that of hot rolled plate, and the tensile strength and elongation to that of cold rolled strip.Tensile properties at elevated temperatures.Proof strength Rp0.2, MPa, minimum values Table 4aSteel grade Temperature, °C 100 200 300 400 5004401 166 137 118 108 1004404 177 147 127 115 1104436 166 137 118 108 1004432 177 147 127 115 1104406 211 167 145 135 1284429 211 167 145 135 1294571 185 167 145 135 1294435 165 137 119 108 100Tensile properties at elevated temperatures.Proof strength Rp1.0, MPa, minimum values Table 4bSteel grade Temperature, °C 100 200 300 400 5004401 199 167 145 135 1284404 211 117 156 144 1394436 199 167 145 135 1284432 211 177 156 144 1394406 246 198 175 164 1584429 246 198 175 164 1584571 218 196 175 164 1584435 200 165 145 135 128Mechanical properties at low temperatures.Proof strength Rm, MPa, minimum values Table 5Steel grade Temp Rp0.2 Rp1.0 Rm A5 °C MPa MPa MPa %4404* -80 275 355 840 404404* -196 350 450 1200 354406** -80 380 450 800 354406** -196 600 700 1150 30Values from EN 10028-7* 4401, 4571, 4432, 4436 and 4435 have approximately the same values as 4404.** 4429 has approximately the same values as 4406.Tensile properties at elevated temperatures.Proof strength Rm, MPa, minimum values Table 4cSteel grade Temperature, °C 100 200 300 400 5004401 430 390 380 380 3604404 430 390 380 - -4436 430 390 380 380 3604432 460 420 410 410 3904406 520 460 440 - -4429 520 460 440 435 4304571 440 390 375 375 3604435 420 380 370 - -Mechanical properties. Hot rolled plate/cold rolled strip and sheet, typical values at 20°C Table 3Steel grade Proof strength Tensile strength Elongation Hardness Rp0.2 Rp1.0 Rm A5 HB MPa MPa MPa % 4401 280/290 320/320 570/590 55/55 1604404 280/290 320/320 570/590 55/55 1654436 300/300 340/340 590/600 50/55 1654432 280/300 320/330 570/600 50/55 1654406 320/ 360/ 620/ 50/ 4429 350/350 390/390 670/670 45/45 1804571 270/270 310/310 570/590 50/55 1654435 270/300 310/340 570/600 55/55 1503120Temperature, °C01008060402010 20 30 40 50 60 70 80 90 100H2SO4%43014436904L44364301Standard Cr-Ni-Mo Stainless SteelsPhysical propertiesThe physical properties are the same for all steel grades in this group.Data according to EN 10088. Physical properties, typical values at 20°C Table 6Density kg/dm3 8.0Modulus of elasticity GPa 200Poissons ratio 0.3Thermal conductivity W/m°C 15Heat capacity J/kg°C 500Electrical resistivity µOm 0.75Physical properties at elevated temperatures.Linear expansion (RT?T) x 10-6/°C Table 7aSteel grade Temperature, °C 100 200 300 400 5004571 16.5 17.5 18.0 18.5 19.0Non-Ti-stabilisedgrades 16.0 16.5 17.0 17.5 18.0Physical properties at elevated temperatures.Modulus of elasticity, GPa Table 7bSteel grade Temperature, °C 100 200 300 400 500All grades 194 186 179 172 165Corrosion ResistanceThe Cr-Ni-Mo standard stainless steels have a versatile cor-rosion resistance and are suitable for a wide range of app-lications. The grades with molybdenum content of 2.6 per cent (4432, 4436, 4435, 4429) have somewhat enhanced corrosion resistance compared to the grades with molyb-denum content of 2.1 per cent (4404, 4401,4406, 4571). A brief description of their resistance to different types of corrosion follows below. For a more detailed description of their corrosion resistance properties in different environ-ments, please refer to our Corrosion Handbook. Uniform corrosionUniform corrosion is characterised by a uniform attack on the steel surface that has come into contact with a corrosive medium. The corrosion resistance is generally considered good if the corrosion rate is less than 0.1 mm/year.This group of Cr-Ni-Mo grades have a good resistance in many organic and inorganic chemicals. An example of an isocorrosion diagram is shown in figure 1.Fig. 1. Isocorrosion diagram for 4301, 4436 and 904L in stagnant sulphuric acid. The curves repre-sent a corrosion rate of 0.1 mm/y. The dashed line represents the boiling point.Pitting and crevice corrosionThe resistance to pitting and crevice corrosion can be enhan-ced by increasing the content of chromium, molybdenum and nitrogen. These grades have a significantly better resis-tance to these types of localised corrosion than the standard Cr-Ni grades.For better resistance, higher alloyed grades such as 2205 and 254 SMO are recommended (see Figure 2).Figure 3 shows up to which approximate temperatures stain-less steel can be used in oxygen-saturated solutions of varying chloride content. There is an additional risk for stress corro-sion cracking at temperatures above 50°C.CPT, °C1008060402004301 4401 4436 SAF 2304 2205 254 SMOFig. 2. Critical pitting temperatures (CPT) in 1M NaCl according to ASTM G 150 using the Avesta Cell. Typical values.MPa80070060050040030020010000 5 10 15 20 25Cold working. %Rp0.2A5% HB807060504030 30020 20010 1000RmA5HB4 Standard Cr-Ni-Mo Stainless SteelsStress corrosion crackingThese austenitic grades – like the standard Cr-Ni steels – are susceptible to stress corrosion cracking (SCC).Critical service conditions, i.e. applications subjected to combinations of tensile stresses, temperatures above about 50°C and certain solutions, especially those containing chlo-rides, should be avoided.For applications demanding high resistance to SCC, the duplex grades 2205, 2304, and LDX 2101 are more suitable.Stress corrosion cracking may also occur in hot alkaline solu-tions (above 110°C).Intergranular corrosionIntergranular corrosion is not a common problem for modern stainless steels since the carbon content is generally kept at a low level. Operations that increase the risk for intergranular corrosion are welding of heavy gauges, heat treatment operations wit-hin the critical temperature interval (550 – 850°C) and slow cooling after heat treatment or hot forming. Ti-stabilised steels and steels with low carbon content (0.02%) have bet-ter resistance towards intergranular corrosion after such ope-ration conditions.FabricationHot formingHot working can be carried out in the 850 – 1150°C range. For maximum corrosion resistance, forgings should be anne-aled at 1070°C and rapidly cooled in air or water after hot working operations.Cold formingThese grades can be readily formed and fabricated by a full range of cold working operations. They can be used in heading, drawing and bending. Any cold working operations Fig. 3. Risk of pitting and crevice corrosion on con-ventional stainless steel in water of different chloride content or temperature.will increase the strength and hardness of the material (see Figure 4) and may leave it slightly magnetic. For more infor-mation on deep drawing, contact Avesta Research Centre.Heat treatmentAnnealingQuench annealing should be performed at 1030 – 1110°C and followed by rapid cooling in water or air.For Ti-stabilised grades, annealing temperatures above 1070°C may impair the resistance to intergranular corrosion.Ti-stabilised grades may also be given a stabilising treatment at lower temperatures. However, temperatures below 980°C should only be used after due consideration of the intended service environment.In applications where high residual stresses cannot be accep-ted, stress relief treatment may be necessary.This can be performed by annealing as outlined above, but may also be performed at lower temperatures.Please contact Outokumpu Stainless for further information.HardeningThese grades cannot be hardened by heat treatment.However, they can be hardened by cold working.MachiningThese austenitic grades are more difficult to machine than ordinary carbon steels but are still comparatively easy to machine compared to more highly alloyed stainless grades. Unless modified for improved machinability, they require higher cutting forces than carbon steels, show resistance to chip breaking and a high tendency to built-up edge forma-tion. The best machining results are obtained by using high-power equipment, sharp tooling and a rigid set-up.The machinability of these grades in relation to other stain-less steels is indicated by the machinability index in Figure 5. Fig. 4. 4404 work-hardening at cold working.Temperature, C°80604020100 1000 10000 100000 Cl- ppm p=pitting, solid line c=crevice corrosion, dashed line4307 c2205 p4307 p4404 p4404 c2205 c5Standard Cr-Ni-Mo Stainless SteelsMachinability index1.41.210.80.60.40.20 4436 4301 4571 4436 2205 PRODEC®Machining withcemented carbide tools high speed steel toolsWeldingThese grades can be readily welded by a full range of con-ventional welding methods such as:• Shielded metal arc welding (SMAW)• Gas tungsten arc welding, TIG (GTAW)• Gas metal arc welding, MIG (GMAW)• Flux-cored arc welding (FCAW)• Plasma arc welding (PAW)• Submerged arc welding (SAW)This index, which rises with increased machinability, is based on a compounded evaluation of test data from several dif-ferent machining operations. It gives an indication of the machinability of different stainless steel grades in relation to that of grade 4436. It should be noted that it does not describe the relative difficulty of machining with cemented carbide and high speed steel tools. Nitrogen alloyed stainless steels are more difficult to machine.Better machinability performance is given by PRODEC ver-sions, which have been modified for improved machinability. PRODEC is available as hot rolled plate and bar in 4401, 4404, 4436 and 4432.For more information, contact Avesta Research Centre.The following welding filler metals from Avesta Welding are recommended:Other filler metals with a molybdenum content higher than that of the base metal may also be used. For further infor-mation, contact Avesta Welding or see www.avestawelding.com.Products•Hot rolled plate, sheets and strip•Cold rolled plate, sheet and coil•Cold rolled narrow strip•Welded tube and pipe•Bar•Rod•Billet•Welding consumablesFig. 5. Relative machinability for some stainless steel grades. Table 8Steelgrade Filler4401 316L/SKR4404 316L/SKR4436 316L/SKR4432 316L/SKR4406 316L/SKR4429 316L/SKR4571 318/SKNb, 316L/SKR4435 316L/SKR6 Standard Cr-Ni-Mo Stainless Steels1198EN-GB:2. Centrum Tryck AB, Avesta, Sweden. March 2006. www.outokumpu.com/stainlessOutokumpu Stainless AB, Avesta Research CentreBox 74, SE-774 22 Avesta, Sweden Tel. +46 (0)226 810 00, Fax +46 (0)226 810 77Outokumpu is a dynamic metals and technology group with a clear target to become the number one in stainless steel. Customer in a wide range of industries use our metal products, technologies and services worldwide. We are dedicated to helping our customers gain competitive advantage. We call this promise the Outokumpu factor.EN 10088-1 Stainless steels – List of stainless steels (Not for ordering)EN 10088-2 Stainless steels – Sheet/plate and strip for general purposesEN 10088-3 Stainless steels – Semi-finished products, bars, rods, sections for general purposesEN 10028-7 Flat products for pressure purposes – Stainless steelsEN 10272 Stainless steel bars for pressure purposesASTM A240/ASME SA-240 Heat-resisting Cr and Cr-Ni stainless steel plate, sheet and strip for pressure vesselsASTM A480 General requirements for flat-rolled stainless and heat resisting steelASTM A959 Harmonized standard grade compositions for wrought stainlessASTM A666/ASME SA-666 Austenitic stainless steel sheet, strip, plate, bar for structural and architectural applicationsMaterial Standards Table 9Information given in this brochure may be subject to alterations without notice. Care has been taken to ensure that the contents of this publication are accurate but Outokumpu Stainless and its a?liated companies to not accept responsibility for errors or for information which is found to be misleading. Suggestions for or descriptions of the end use or application of products or methods of working are for information only and Outokumpu Stainless and its a?liated companies accept no liability in respect thereof. Before using products supplied or manufactured by the company the costumer should satisfy himself of their suitability.