Nickel Alloy Inconel X-750-HTH
Precip hard
UNS N07750 · EN 2.4669, NiCr15Fe7TiAl
HTH = equalized 885 °C/24 h + aged 704 °C/20 h
Highest room- and mid-temperature strength condition for bolting, bar and forgings used below ~650 °C.
Values for the HTH condition
Other Inconel X-750 tempers and conditions
Inconel X-750 is listed in 7 conditions; see the grade overview at Inconel X-750.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest, most formable and weldable condition; used as supply state for forming, deep drawing and machining before ageing. | 350 | 830 | 45 | 180 HB | — |
Equalized | Intermediate stabilising treatment for bar/forgings that will be single-aged; gives best RT and mid-temperature strength after ageing. | 480 | 900 | 35 | 18 HRC | 1.4 % IACS |
STADefault Solution treated and aged | Standard turbine/aerospace condition (AMS 5667 bar): best balance of RT strength, creep-rupture and stress-relaxation resistance to ~700 °C. | 815 | 1,200 | 25 | 32 HRC | — |
HTHThis page Equalized 885 °C/24 h + aged 704 °C/20 h | Highest room- and mid-temperature strength condition for bolting, bar and forgings used below ~650 °C. | 860 | 1,275 | 23 | 35 HRC | — |
Hot rolled / hot finished + aged 732 °C/16 h | Economical bar/rod condition for bolts, studs and general high-temperature hardware below ~600 °C. | 900 | 1,300 | 22 | 36 HRC | 1.4 % IACS |
Spring hard | Cold-worked wire/strip supplied for coiling or forming; must be aged after forming to develop final spring properties. | 1,170 | 1,380 | 6 | 42 HRC | 1.4 % IACS |
Cold drawn + aged 732 °C/16 h | Final condition for high-temperature springs, clips and seals: highest strength and best stress-relaxation resistance to ~540–650 °C. | 1,280 | 1,550 | 8 | 45 HRC | 1.4 % IACS |
What is Inconel X-750-HTH?
Inconel X-750-HTH is Inconel X-750 in the HTH condition — highest room- and mid-temperature strength condition for bolting, bar and forgings used below ~650 °C. Inconel X-750-HTH has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 91% of nickel alloy grades. Elongation at break is 23% and the elastic modulus is 214 GPa (31 Msi). Inconel X-750-HTH has a density of 8.28 g/cm³ (0.299 lb/in³), lighter than 55% of nickel alloy grades. It melts at 1,393°C (2,539 °F). STA is the default condition FabDigit quotes; HTH is available on request or by drawing note.
Advantages
- High strength — 860 MPa (125 ksi), better than 91% of nickel alloy grades
Limitations
- Difficult to weld — 35/100, worse than 76% of nickel alloy grades
Inconel X-750-HTH properties
Typical room-temperature values for Inconel X-750-HTH; 11 are specific to this condition. Other listed values are Inconel X-750 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Inconel X-750-HTH has a density of 8.28 g/cm³ (0.299 lb/in³), lighter than 55% of nickel alloy grades. It melts at 1,393°C (2,539 °F).
Mechanical16
Inconel X-750-HTH has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 91% of nickel alloy grades. Elongation at break is 23% and the elastic modulus is 214 GPa (31 Msi).
Thermal6
Inconel X-750-HTH is rated for continuous service to 650°C (1,202 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), better than 65% of nickel alloy grades. Thermal expansion is 12.6 µm/m·K (7 µin/in·°F).
Electrical3
Inconel X-750-HTH conducts electricity at 1.4 % IACS, worse than 65% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 61% of nickel alloy grades.
Sustainability4
Producing a kilogram of Inconel X-750-HTH takes about 190 MJ of energy and emits 13 kg of CO₂ — more than 75% of nickel alloy grades. Typical recycled content is 35%.
Manufacturability8
Inconel X-750-HTH's machinability is not recommended (14/100, worse than 81% of nickel alloy grades); weldability fair (35/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Inconel X-750-HTH
Is Inconel X-750 easy to machine?
Machine preferably in the annealed state with rigid setups, positive-rake carbide or ceramic tooling, low speed / heavy feed and flood coolant; aged material work-hardens sharply and needs sharp edges and no dwelling.
Can Inconel X-750 be welded?
GTAW with matching X-750 or Inconel 718/A-type filler; weld in the annealed condition, keep heat input low and re-solution-treat before ageing to avoid strain-age (post-weld heat treatment) cracking.
Can Inconel X-750 be formed, bent or molded?
Cold form only in the annealed or equalized condition — springback is large and forces are ~2× those for stainless; hot work at 1150–950 °C and re-anneal after heavy deformation.
What surface finishes work on Inconel X-750?
Not anodizable; use pickling/passivation, electropolishing, glass-bead or vapour blast, and vacuum heat treatment for bright surfaces; oxide films from ageing must be removed before brazing or plating.
Inconel X-750 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cr | 14 – 17 | 15.5 |
| Fe | 5 – 9 | 7 |
| Tiγ′ former | 2.25 – 2.75 | 2.5 |
| Alγ′ former | 0.4 – 1 | 0.7 |
| NbNb + Ta | 0.7 – 1.2 | 0.95 |
| Co | ≤ 1 | 0.2 |
| Mn | ≤ 1 | 0.3 |
| Si | ≤ 0.5 | 0.2 |
| Cu | ≤ 0.5 | 0.05 |
| C | ≤ 0.08 | 0.04 |
| S | ≤ 0.01 | 0 |
| NiNi + Co, balance | ≥ 70 (balance) | — |
Inconel X-750-HTH — frequently asked
What is Inconel X-750-HTH used for?
Inconel X-750-HTH is typically used for gas turbine blades and bolts, springs at elevated temperature, jet engine seals and nuclear reactor springs. In short: hot spring-temper superalloy; γ′ strength to 704 °C; stronger than 600 series nickel.
What is the yield strength of Inconel X-750-HTH?
Inconel X-750-HTH has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 91% of nickel alloy grades. Strength varies by condition: see the 7 listed tempers.
Is Inconel X-750-HTH easy to machine?
Not especially — machinability is rated not recommended (14/100, worse than 81% of nickel alloy grades). Machine preferably in the annealed state with rigid setups, positive-rake carbide or ceramic tooling, low speed / heavy feed and flood coolant; aged material work-hardens sharply and needs sharp edges and no dwelling.
Can Inconel X-750-HTH be welded?
With care — weldability is rated fair (35/100). GTAW with matching X-750 or Inconel 718/A-type filler; weld in the annealed condition, keep heat input low and re-solution-treat before ageing to avoid strain-age (post-weld heat treatment) cracking.
What surface finishes work on Inconel X-750-HTH?
Not anodizable; use pickling/passivation, electropolishing, glass-bead or vapour blast, and vacuum heat treatment for bright surfaces; oxide films from ageing must be removed before brazing or plating.
Can Inconel X-750-HTH be formed, bent or molded?
Cold form only in the annealed or equalized condition — springback is large and forces are ~2× those for stainless; hot work at 1150–950 °C and re-anneal after heavy deformation.
What is the maximum service temperature of Inconel X-750-HTH?
Inconel X-750-HTH is rated for continuous use to about 650°C (1,202 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Inconel X-750-STA and Inconel X-750-ANN?
STA is the default condition — standard turbine/aerospace condition (AMS 5667 bar): best balance of RT strength, creep-rupture and stress-relaxation resistance to ~700 °C. ANN: softest, most formable and weldable condition; used as supply state for forming, deep drawing and machining before ageing. Yield strength is 815 MPa in STA versus 350 MPa in ANN.
Sources
- INCONEL alloy X-750 technical bulletin — Special Metals Corporation (2004)
- AMS 5542 — Nickel Alloy Sheet, Strip and Plate, Precipitation Heat Treatable — SAE International (2018)
- AMS 5667/5668/5670/5671 — Nickel Alloy Bars, Forgings and Rings (N07750) — SAE International (2017)
- ASTM B637 — Precipitation-Hardening Nickel Alloy Bars, Forgings and Forging Stock for High-Temperature Service — ASTM International (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 14992 / GH4145 — SAC (2005)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.