Alloy 740H
Precipitation-hardened nickel alloy developed for advanced ultra-supercritical boilers. Gamma-prime strengthening plus about 25% chromium holds creep rupture strength and coal-ash corrosion resistance at 750 C and above, which is beyond what 617 can carry in thick section steam headers.
- Gamma-prime strengthened for 750 C steam service
- ASME Code Case 2702 qualified for AUSC boilers
- Coal-ash and steam-side oxidation resistance at temperature
- Supplied solution treated and aged, with full heat traceability
Available forms & sizes
| Form | Size range |
|---|---|
| Seamless Pipes & Tubes | 1/2" - 16" NB, SCH 10S - SCH 160, seamless |
| Seamless Pipes & Tubes | 6 - 88.9 mm OD tube, BA / bright annealed finish |
| Plates | 3 - 50 mm thk, hot rolled and solution annealed |
| Round Bars | 10 - 300 mm dia |
Chemical composition (%)
| Element | Min | Max |
|---|---|---|
| Ni | Balance | - |
| Cr | 23.5 | 25.5 |
| Co | 15.0 | 22.0 |
| Nb | 0.50 | 2.50 |
| Ti + Al | 1.80 | 3.00 |
Mechanical properties
| Property | Value | Unit |
|---|---|---|
| Yield Strength (0.2%) | 620 min (aged) | MPa |
| Tensile Strength | 1000 min (aged) | MPa |
| Elongation | 20 min | % |
| Condition | Solution treated and aged | - |
Physical properties
| Property | Value | Unit |
|---|---|---|
| Density | 8.05 | g/cm3 |
| Max Service Temperature | 800 | C |
Typical applications
Frequently asked
[ 02 ] Other grades in Nickel Alloys
Inconel 625
Mill indentNickel-chromium-molybdenum alloy strengthened by niobium. Exceptional strength and corrosion resistance from cryogenic temperatures to 980 C without heat treatment.
Inconel 600
Mill indentSolid solution nickel-chromium-iron alloy with high resistance to oxidation, carburisation and chloride ion stress corrosion cracking at elevated temperature.
Monel 400
Mill indentNickel-copper alloy with outstanding resistance to flowing seawater, hydrofluoric acid and alkalis, and total immunity to chloride stress corrosion cracking.
Hastelloy C276
Mill indentNickel-molybdenum-chromium alloy with tungsten, regarded as the most universally corrosion resistant alloy available for both oxidising and reducing media.
Alloy 800 (Incoloy 800)
Mill indentIron-nickel-chromium alloy for high temperature strength with oxidation and carburisation resistance. The 32Ni-21Cr balance resists chloride stress corrosion cracking that austenitic stainless suffers, which is why it is standard for process heater and reformer tubing.
Alloy 800HT (Incoloy 800HT)
Mill indentThe creep-optimised version of Alloy 800. Controlled carbon plus a combined aluminium and titanium window of 0.85 - 1.20% gives far better creep rupture strength above 600 C, so 800HT is the grade for the hottest reformer and pigtail service rather than plain 800.