Properties
General
Mechanical
| Property | Temperature | Value | Comment |
|---|---|---|---|
Elastic modulus | 20.0 °C | 197 GPa Show Supplier Material materials with Elastic modulus of 197 GPa | |
100.0 °C | 189 GPa Show Supplier Material materials with Elastic modulus of 189 GPa | ||
200.0 °C | 178 GPa Show Supplier Material materials with Elastic modulus of 178 GPa | ||
300.0 °C | 168 GPa Show Supplier Material materials with Elastic modulus of 168 GPa | ||
Elongation | 23.0 °C | 25 % Show Supplier Material materials with Elongation of 25 % | min. |
Elongation A2 | 23.0 °C | 25 % Show Supplier Material materials with Elongation A2 of 25 % | min. |
Hardness, Rockwell C | 23.0 °C | 34 [-] Show Supplier Material materials with Hardness, Rockwell C of 34 [-] | max. |
Tensile strength | 20.0 °C | 920 - 1100 MPa Show Supplier Material materials with Tensile strength of 920 - 1100 MPa | |
50.0 °C | 900 MPa Show Supplier Material materials with Tensile strength of 900 MPa | ||
100.0 °C | 850 MPa Show Supplier Material materials with Tensile strength of 850 MPa | ||
150.0 °C | 840 MPa Show Supplier Material materials with Tensile strength of 840 MPa | ||
200.0 °C | 830 MPa Show Supplier Material materials with Tensile strength of 830 MPa | ||
250.0 °C | 810 MPa Show Supplier Material materials with Tensile strength of 810 MPa | ||
300.0 °C | 790 MPa Show Supplier Material materials with Tensile strength of 790 MPa | ||
Yield strength Rp0.1 | 20.0 °C | 800 MPa Show Supplier Material materials with Yield strength Rp0.1 of 800 MPa | min. |
50.0 °C | 760 MPa Show Supplier Material materials with Yield strength Rp0.1 of 760 MPa | min. | |
100.0 °C | 670 MPa Show Supplier Material materials with Yield strength Rp0.1 of 670 MPa | min. | |
150.0 °C | 640 MPa Show Supplier Material materials with Yield strength Rp0.1 of 640 MPa | min. | |
200.0 °C | 590 MPa Show Supplier Material materials with Yield strength Rp0.1 of 590 MPa | min. | |
250.0 °C | 570 MPa Show Supplier Material materials with Yield strength Rp0.1 of 570 MPa | min. | |
300.0 °C | 560 MPa Show Supplier Material materials with Yield strength Rp0.1 of 560 MPa | min. | |
Yield strength Rp0.2 | 20.0 °C | 700 MPa Show Supplier Material materials with Yield strength Rp0.2 of 700 MPa | min. |
50.0 °C | 645 MPa Show Supplier Material materials with Yield strength Rp0.2 of 645 MPa | min. | |
100.0 °C | 600 MPa Show Supplier Material materials with Yield strength Rp0.2 of 600 MPa | min. | |
150.0 °C | 560 MPa Show Supplier Material materials with Yield strength Rp0.2 of 560 MPa | min. | |
200.0 °C | 540 MPa Show Supplier Material materials with Yield strength Rp0.2 of 540 MPa | min. | |
250.0 °C | 510 MPa Show Supplier Material materials with Yield strength Rp0.2 of 510 MPa | min. | |
300.0 °C | 500 MPa Show Supplier Material materials with Yield strength Rp0.2 of 500 MPa | min. | |
Thermal
| Property | Temperature | Value | Comment |
|---|---|---|---|
Coefficient of thermal expansion | 100.0 °C | 1.25E-5 1/K Show Supplier Material materials with Coefficient of thermal expansion of 1.25E-5 1/K | for 30°C to the mentioned temperature |
200.0 °C | 1.3E-5 1/K Show Supplier Material materials with Coefficient of thermal expansion of 1.3E-5 1/K | for 30°C to the mentioned temperature | |
300.0 °C | 1.4E-5 1/K Show Supplier Material materials with Coefficient of thermal expansion of 1.4E-5 1/K | for 30°C to the mentioned temperature | |
Specific heat capacity | 20.0 °C | 470 J/(kg·K) Show Supplier Material materials with Specific heat capacity of 470 J/(kg·K) | |
100.0 °C | 495 J/(kg·K) Show Supplier Material materials with Specific heat capacity of 495 J/(kg·K) | ||
200.0 °C | 530 J/(kg·K) Show Supplier Material materials with Specific heat capacity of 530 J/(kg·K) | ||
300.0 °C | 560 J/(kg·K) Show Supplier Material materials with Specific heat capacity of 560 J/(kg·K) | ||
400.0 °C | 590 J/(kg·K) Show Supplier Material materials with Specific heat capacity of 590 J/(kg·K) | ||
Thermal conductivity | 20.0 °C | 12 W/(m·K) Show Supplier Material materials with Thermal conductivity of 12 W/(m·K) | |
100.0 °C | 14 W/(m·K) Show Supplier Material materials with Thermal conductivity of 14 W/(m·K) | ||
200.0 °C | 16 W/(m·K) Show Supplier Material materials with Thermal conductivity of 16 W/(m·K) | ||
300.0 °C | 18 W/(m·K) Show Supplier Material materials with Thermal conductivity of 18 W/(m·K) | ||
400.0 °C | 19 W/(m·K) Show Supplier Material materials with Thermal conductivity of 19 W/(m·K) | ||
Electrical
| Property | Temperature | Value |
|---|---|---|
Electrical resistivity | 23.0 °C | 7.5E-7 Ω·m Show Supplier Material materials with Electrical resistivity of 7.5E-7 Ω·m |
Chemical properties
| Property | Value | Comment | |
|---|---|---|---|
Carbon | 0.03 % Show Supplier Material materials with Carbon of 0.03 % | max. | |
Chromium | 27 % Show Supplier Material materials with Chromium of 27 % | ||
Cobalt | 1 % Show Supplier Material materials with Cobalt of 1 % | ||
Iron | Balance | ||
Manganese | 1.5 % Show Supplier Material materials with Manganese of 1.5 % | max. | |
Molybdenum | 4.8 % Show Supplier Material materials with Molybdenum of 4.8 % | ||
Nickel | 6.5 % Show Supplier Material materials with Nickel of 6.5 % | ||
Nitrogen | 0.4 % Show Supplier Material materials with Nitrogen of 0.4 % | ||
Phosphorus | 0.04 % Show Supplier Material materials with Phosphorus of 0.04 % | max. | |
Silicon | 0.5 % Show Supplier Material materials with Silicon of 0.5 % | max. | |
Sulfur | 0.01 % Show Supplier Material materials with Sulfur of 0.01 % | max. | |
Technological properties
| Property | ||
|---|---|---|
| Application areas | Typical applications for Sandvik SAF 2707 HD™ are tubular heat exchangers operating in process industries, such as oil refineries, petrochemical and chemical plants. | |
| Certifications | Approvals: | |
| Cold Forming | The force needed for bending Sandvik SAF 2707 HD™ is higher than that for standard austenitic stainless steels, which is a natural consequence of higher proof strength. However, cold bending can be carried out with normal bending methods, and owing to its good ductility, Sandvik SAF 2707 HD™ can be bent to very close bending radii. Normally, there is no need for subsequent heat treatment. Heat treatment, if any, should be carried out by solution or resistance annealing. For pressure vessel applications using cold bent tubes, special conditions may apply regarding the minimum bending radii allowed without subsequent heat treatment. | |
| Corrosion properties | General corrosion: Sandvik SAF 2707 HD™ is highly resistant to organic acid corrosion, e.g. formic acid and acetic acid, see Figures 2 to 5. It also remains resistant in contaminated acid. The alloy is, therefore, a competitive alternative to high alloyed austenitic stainless steels and Ni-base alloys in applications where standard austenitic stainless steels corrode at a high rate. Resistance to inorganic acids is comparable to, or even better than that of high alloy austenitic stainless steels in certain concentration ranges. Figure 6 shows an isocorrosion diagram for sulphuric acid, where the resistance of Sandvik SAF 2707 HD™ in up to 50% H₂SO₄ exceeds the resistance of Sandvik SAF 2507® and 316L. Pitting and crevice corrosion: The pitting and crevice corrosion resistance of stainless steel is primarily determined by the content of chromium, molybdenum and nitrogen. An index for comparing the resistance to pitting and crevice corrosion in chloride environments is the PRE number (Pitting Resistance Equivalent). The PRE is defined as, in weight % : PRE=%Cr + 3.3x%Mo + 16x%N. The minimum PRE value for SAF 2707 HD™ is 48. One of the most severe pitting corrosion tests, applied to stainless steels, is ASTM G48 i.e. exposure to 6% FeCl₃. In a modified version of the ASTM G48A test, the sample is exposed for periods of 24 hours. When pits are detected, together with a substantial weight loss (> 5 mg), the test is interrupted. Otherwise, the temperature is increased by 5°C (9°F) and the test continued with the same sample. The corrosion resistance of Sandvik SAF 2707 HD™ in oxidizing chloride solutions is illustrated by critical pitting temperature (CPT), determined in a "Green-Death" solution (1% FeCl₃ + 1%CuCl₂ + 11% H₂SO₄ + 1.2%HCl). The crevice corrosion test was performed in 6% FeCl₃ with a crevice specified in the MTI-2 procedure, where an artificial crevice is mounted on the sample with a torque of 0.28 Nm. The values obtained and a comparison with Sandvik SAF 2507 are given in Figure 7. All test results show significantly higher values for Sandvik SAF 2707 HD™ than for Sandvik SAF 2507®. Potentiostatic tests in solutions with different chloride contents are reported in Figure 8. The CPT value for Sandvik SAF 2707 HD™ is significantly better than for Sandvik SAF 2507® in highly concentrated chloride solutions. Figure 9 shows the effect of increased acidity. Sandvik SAF 2707 HD™ shows higher CPT values than austenitic stainless steels of the 6Mo+N type, especially at low pH values. In both cases the applied potential is 600mV vs SCE, a very high value compared with that which could be expected in natural, unchlorinated seawater, resulting in lower critical temperatures compared with most practical service conditions. Full scale extended heat exchanger tests in chlorinated natural seawater heated to two different temperatures. The very good pitting corrosion results in laboratory tests have also been verified in full scale extended heat exchanger tests in chlorinated natural seawater. The residual chlorine content was 0.5 ppm. Model heat exchangers and heat exchanger tubing in Sandvik SAF 2707 HD™ and Sandvik SAF 2507®, welded into UNS S32750 tube sheets and SAF 2205 welded into a UNS S32205 tube sheet were tested for 6 months at each temperature. The inlet temperature of the seawater was 35°C with a seawater flow rate inside the tubes of 1 m/s. Heat was applied from the shell side with external heating elements and thus a heat flux through the tubes was achieved. As the results in the table show, no pitting was observed on Sandvik SAF 2707 HD™ when the tube skin temperature on the seawater side was 70°C, after tubes were heated from the outside at a temperature of 105°C. At this temperature Sandvik SAF 2507® experienced pitting, but passed at 50°C. Sandvik SAF 2205™ was attacked by pitting at both temperatures. Stress corrosion cracking: The stress corrosion cracking resistance of Sandvik SAF 2707 HD™ in chloride environments is excellent. SCC resistance of Sandvik SAF 2707 HD™ in chloride solutions at high temperatures is illustrated in Figure 10. In these tests, there were no signs of SCC up to 1000 ppm Cl-/300°C (572°F) and 10000 ppm Cl-/250°C (482°F). | |
| Expanding | Compared to austenitic stainless steels, Sandvik SAF 2707 HD™ has higher proof and tensile strengths. This must be kept in mind when expanding tubes into tubesheets. Normal expanding methods can be used, but the expansion requires higher initial force and should be undertaken in a one-step operation. If the service conditions include a high chloride concentration, tube to tubesheet joints should generally be welded, in order to reduce the risk of crevice corrosion. | |
| Heat Treatment | Tubes are normally delivered in the heat treated condition. If additional heat treatment is needed due to further processing, solution annealing is recommended. Please contact Sandvik for further information. | |
| Machining | Being a dual phase material (austenitic-ferritic), Sandvik SAF 2707 HD™ will present a different tool wear profile from that of austenitic stainless steels. The cutting data (speed and feed) must, therefore, be lower than that recommended for austenitic grades. Further information is available on request. | |
| Other | Forms of supply: Seamless tubes in Sandvik SAF 2707 HD™ can be supplied in typical heat exchanger tube dimensions. Tubes are generally delivered solution annealed, with a pickled or light ground surface condition. | |
| Welding | The weldability of Sandvik SAF 2707 HD™ is good. Welding must be carried out without preheating and subsequent heat treatment is normally not necessary. Suitable method of fusion welding is gas tungsten arc welding GTAW/TIG with shielding gas of Ar+2% N₂. For tube to tubesheet welding, it is recommended to use Ar+3% N₂ as shielding gas to have proper weld metal structure. For Sandvik SAF 2707 HD™, heat input of 0.2-1.5 kJ/mm and interpass temperature of <100°C (210°F) are recommended. Recommended filler metals: | |