Cross reference
Other names for NiCr18Co15TiMoAl
Buyers ask for this alloy under several names depending on which standard their drawing was written to. All of the entries below cover the same UDIMET 720 chemistry.
| System | Designation | Note |
|---|---|---|
| Europe, material name | NiCr18Co15TiMoAl | Used on European mill certificates |
| United States, trade name | UDIMET 720, U720, Alloy 720 | UDIMET is a registered trade mark of Special Metals Corporation |
| UNS | N07720 | Unified Numbering System |
| France, producer grade | PER72 | Aubert & Duval |
| France, AFNOR | NC18K15TDA | |
| Low interstitial version | U720Li, Alloy 720Li, GH4720Li | Reduced Cr, C and B. Not interchangeable with U720 |
Trade marks belong to their owners and appear here only to identify the grade. We are an independent forging factory with no affiliation to the trade mark holders. Our UDIMET 720 page covers the same material.
Chemistry
Chemical composition of NiCr18Co15TiMoAl
Limits in weight percent. Titanium and aluminium form the gamma prime phase that carries most of the strength. Molybdenum and tungsten stiffen the matrix. Zirconium and boron sit at the grain boundaries and are held to a few hundredths of a percent.
| El. | Element | Content (%) | Proportion |
|---|---|---|---|
| Ni28 | Nickel | 55.16 to 59.705, bal. | |
| Cr24 | Chromium | 15.50 to 16.50 | |
| Co27 | Cobalt | 14.00 to 15.50 | |
| Ti22 | Titanium | 4.75 to 5.25 | |
| Mo42 | Molybdenum | 2.75 to 3.25 | |
| Al13 | Aluminium | 2.25 to 2.75 | |
| W74 | Tungsten | 1.00 to 1.50 | |
| Zr40 | Zirconium | 0.025 to 0.050 | |
| B5 | Boron | 0.010 to 0.020 | |
| C6 | Carbon | 0.010 to 0.020 |
Bar length follows the mid range figure, so the trace elements show as a sliver. Heat specific analysis is reported on the EN 10204 certificate that ships with the order.
Properties
Mechanical properties of NiCr18Co15TiMoAl
Room temperature minima, solution treated and aged. What a given forging reaches depends on section size, how much reduction it saw and the cycle it was heat treated to.
| Property | Imperial | Metric |
|---|---|---|
| Tensile strength, Rm | 160 ksi min | 1,100 MPa min |
| Yield strength, Rp0.2 | 130 ksi min | 895 MPa min |
| Elongation, A | 5 % min | 5 % min |
These are acceptance minima, not design allowables. For design work use the procurement specification and the certified test results for the heat you receive.
Processing
Heat treatment
Strength comes from a solution treatment followed by a staged age that precipitates the gamma prime. A cycle commonly run on U720 forgings:
| Stage | Temperature | Time | Cooling |
|---|---|---|---|
| Solution anneal | 1,121 C / 2,050 F | Rapid air cool | |
| Stabilise | 1,113 C / 2,035 F | 2 h | Air cool |
| Intermediate age | 1,079 C / 1,975 F | 4 h | Oil quench |
| First age | 649 C / 1,200 F | 24 h | Air cool |
| Second age | 760 C / 1,400 F | 8 h | Air cool |
Forging, machining, welding
The alloy forges and stays reasonably ductile, but it wants press capacity and a heavy duty lubricant. Every trace of that lubricant has to come off afterwards or the part will embrittle at temperature in service. Machining is conventional once you allow for the strength, the gumminess and how fast it work hardens. For welding we use GTAW, GMAW or SMAW. Submerged arc is not used on this grade, the heat input is high enough to crack it.
What we make
Forged forms in NiCr18Co15TiMoAl
Everything here is made to your drawing, or to finished dimensions if there is no drawing.
Seamless rolled rings
Ring rolled for casings, spacers and seal rings.
Forged rings
Upset and punched, where ring rolling does not pay for the quantity or the section.
Discs and disks
Solid or bored, for rotating turbine parts.
Shafts and spindles
Straight, stepped or eccentric. Black or rough turned.
Flanges
Blind, weld neck style, or a profile off your drawing.
Round bars
Forged bar for machining or as stock for further forging.
Sleeves and bushings
Bored from solid, or trepanned on the larger sizes.
Tubes and pipes
Heavy wall hollows for high temperature service.
Tube sheets and blocks
Tube sheets, valve blocks, bodies and seat rings.
See also forged products, forged crankshafts, or the full range.
Sizes
Size is quoted against the drawing rather than off a standard list, because the forged envelope depends on the machining allowance you want. Send the finished dimensions and we will confirm the forged size, the weight and whether it suits our presses.
Where it goes
Applications
The alloy was designed for rotating turbine parts. The same forged shapes go into other high temperature and corrosive duty as well.
| Sector | Typical components |
|---|---|
| Aero engines and industrial gas turbines | Turbine discs, blade and vane forgings, seal rings, spacers, rolled casing rings, shafts |
| Power generation | Rotor components, gas compressor parts, gearbox gears and spindles, transmission shafts |
| Oil, gas and offshore | Valve bodies, seat rings, stems and blocks, wellhead and christmas tree components, bushings and sleeves for subsea systems |
| Process and pressure equipment | Tube sheets, nozzles, flanges and rings for pressure vessels, shell and tube heat exchangers, columns and towers |
| Heavy machinery | Rolls, wheels, eccentric shafts, crankshafts and manifolds for mills, mixers and processing units |
| Marine, chemical, pharmaceutical | Shafts, sleeves and rings for shipbuilding, pulp and paper, biochemical plant |
If the service does not actually need a gamma prime disc alloy, a cheaper grade often does the job. Waspaloy, Inconel 718 and Inconel 625 are the usual alternatives. Tell us the temperature, the stress and the environment and we will say so before you commit to the grade.
Process and control
Melting, testing, certification
Melting route
Forging stock is melted EAF + VOD + ESR. Electric arc melt, vacuum oxygen decarburisation to refine, then electroslag remelt. The ESR step is what gives the cleanliness and the low segregation you need before open die forging a high gamma prime alloy into a heavy section.
Non destructive testing
Ultrasonic testing to whichever standard the order calls for, usually EN 10228-3, SEP 1921 or ASTM A388. Dye penetrant, magnetic particle, hardness survey and dimensional inspection on request.
Certification
Material ships with an inspection certificate to EN 10204 3.1. If you want 3.2, name the third party and we will arrange it. TUV, BV, SGS, LR and DNV are all routine for us. The certificate carries heat number, analysis, heat treatment condition, mechanical results and the NDT report.
Specification
Forgings, bars and forging stock go out to ASTM B637, which covers precipitation hardening and cold worked nickel alloy bars, forgings and forging stock for moderate or high temperature service. Customer and OEM specifications are fine too, as long as the requirements are on the enquiry.
Next step
How to order
Send a drawing to sales@steelforgepieces.com, or the finished dimensions if there is no drawing. Getting the following in the first email usually saves a round of back and forth:
- Grade and specification. NiCr18Co15TiMoAl, UDIMET 720 or UNS N07720, plus the governing spec if it is not ASTM B637.
- Shape and dimensions, and whether the figures are forged size or finished machined size.
- Quantity, and whether repeats are likely.
- Delivery condition: as forged, rough machined, heat treated, or heat treated and machined.
- UT standard and acceptance class, plus any mechanical or corrosion testing.
- Certificate level, and the inspector if you want 3.2.
- Destination port or address and the Incoterms you work to.
Questions
Questions we get asked
What is NiCr18Co15TiMoAl?
A precipitation hardened nickel base superalloy, sold in the United States as UDIMET 720 and numbered UNS N07720. Molybdenum and tungsten strengthen the matrix, titanium and aluminium form the gamma prime that gives it strength and creep resistance at temperature.
Is NiCr18Co15TiMoAl the same as UDIMET 720?
Yes. NiCr18Co15TiMoAl is the European material name for the same chemistry. Aubert & Duval sell it as PER72 and the AFNOR designation is NC18K15TDA. All four names sit against the same composition table.
What is the UNS number for NiCr18Co15TiMoAl?
N07720. Quoting it on the enquiry is worth doing, it removes any doubt about whether you want U720 or the low interstitial U720Li.
What is the difference between U720 and U720Li?
U720Li carries less chromium, carbon and boron. The lower carbon and boron let the alloy be remelted rather than powder processed, and the lower chromium makes it less prone to sigma phase, so the properties hold up better over a long life at temperature. If your spec says 720Li, say so on the enquiry. The two are not interchangeable.
Which specification covers NiCr18Co15TiMoAl forgings?
ASTM B637 covers precipitation hardening and cold worked nickel alloy bars, forgings and forging stock for moderate or high temperature service, and that is the default. We also work to customer and OEM specifications when the requirements come with the enquiry.
How is NiCr18Co15TiMoAl melted?
EAF + VOD + ESR. Electric arc furnace melt, vacuum oxygen decarburisation, then electroslag remelt for cleanliness and low segregation before forging.
What shapes can be forged in NiCr18Co15TiMoAl?
Seamless rolled rings, forged rings, discs, shafts and spindles, flanges, round bars, sleeves, bushings, heavy wall tubes and pipes, tube sheets, valve bodies, seat rings and blocks. To drawing, or to finished dimensions if you do not have one.
What testing and certification comes with NiCr18Co15TiMoAl forgings?
Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, whichever the order names. Dye penetrant, magnetic particle, hardness and dimensional checks on request. Certificate to EN 10204 3.1, or 3.2 countersigned by a third party inspector you nominate.
Who supplies NiCr18Co15TiMoAl open die forgings?
Jiangyin Jiangnan Metal Co., Ltd., an open die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We ship NiCr18Co15TiMoAl, UDIMET 720 and UNS N07720 forgings worldwide. Write to sales@steelforgepieces.com or call +86 189 2135 9659.
What is needed to quote NiCr18Co15TiMoAl forgings?
Grade and spec, shape and dimensions with a note on whether they are forged or finished size, quantity, delivery condition, UT standard, certificate level, and the destination with Incoterms. A drawing covers most of it.