SAF™ 2707 HD is a high-alloy duplex (austenitic-ferritic) stainless steel for service in highly corrosive conditions. The grade is particularly suited for use in aggressive acidic and chloride containing environments. - Excellent resistance to pitting and crevice corrosion - Excellent resistance to stress corrosion cracking (SCC) in chloride containing environments - High resistance to general corrosion in acidic environments - Excellent resistance to erosion corrosion - Excellent corrosion fatigue properties - Extremely high mechanical strength - Physical properties that offer design advantages - Good weldability Product standards Seamless and welded tube and pipe: ASTM A789, A790 Approvals ASME BPV Code, Section VIII, Divsion 1. Particular Material Appraisal (PMA), austenitic-ferritic steel SAF™ 2707HD (seamless tube): PED (Pressure Equipment Directive) 2014/68/EU and AD2000. Chemical composition (nominal) Chemical composition (nominal) % Datasheet last updated 09.05.2025 6:38:17 (supersedes all previous editions)

Applications Typical applications for SAF™ 2707 HD are tubular heat exchangers operating in process industries, such as oil refineries, petrochemical and chemical plants. Corrosion resistance General corrosion Figure 2. Isocorrosion diagram in naturally aerated formic acid. The curve represents a corrosion rate of 0.1mm/year (4mpy) in a stagnant test solution. Datasheet last updated 09.05.2025 6:38:17 (supersedes all previous editions) 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....

Figure 3. General corrosion resistance of SAF™ 2707 HD and Hastelloy C276 in various concentrations of formic acid at 105°C. Figure 5. Isocorrosion diagram in naturally aerated acetic acid. The curve represents a corrosion rate of 0,1mm/year (4mpy) in a stagnant test solution. 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 SAF™ 2707 HD in up to 50% 3 Datasheet last updated 09.05.2025 6:38:17 (supersedes all previous...

Figure 6. Isocorrosion diagram in naturally aerated sulphuric acid. The curves represent a corrosion rate of 0.1 mm/year (4 mpy) in a stagnant test solution. 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...

Potentiostatic tests in solutions with different chloride contents are reported in Figure 8. The CPT value for SAF™ 2707 HD is significantly better than for SAF™ 2507 in highly concentrated chloride solutions. Figure 9 shows the effect of increased acidity. 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...

Figure 9. Critical pitting temperatures (CPT) in 3% NaCI with varying pH (potentiostatic determination at +600mV SCE with surface ground with 220 grit paper). 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 SAF™ 2707 HD and 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 stress corrosion cracking resistance of SAF™ 2707 HD in chloride environments is excellent. Figure 10. SCC resistance in oxygen-bearing (abt. 8 ppm) neutral chloride solutions. Testing time 1000 hours. Applied stress equal to proof strength at testing temperature. Fabrication Bending The force needed for bending 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, SAF™ 2707 HD can be bent to very close bending...

Being a dual phase material (austenitic-ferritic), 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. Forms of supply Seamless tube Seamless tubes in 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. Heat treatment Tubes are normally delivered in the heat treated condition. If additional...

Imperial units Proof strength, ksi Impact strength SAF™ 2707 HD possesses very good impact strength. Figure 1 shows impact energy (KCV). The ductile-brittle transition temperature is below -50°C (-58°F). Figure 1. Impact energy curve for SAF™ 2707 HD using standard Charpy V specimens 10 x 10mm (average of 3 at 9 Datasheet last updated 09.05.2025 6:38:17 (supersedes all previous editions)

each temperature). The samples are taken in the longitudinal and transversal direction from 200 x13 mm hot extruded and solution annealed (1100oC / 2012oF) tube. Physical properties Density: 7.8 g/cm3, 0.28lb/in3 Specific heat capacity Metric units, Imperial units Thermal conductivity Thermal expansion SAF™ 2707 HD has a coefficient of thermal expansion at the same level as carbon steel. The values given are average values in the temperature ranges. Datasheet last updated 09.05.2025 6:38:17 (supersedes all previous editions)