ASTM B637 ASME SB637 UNS N07718 Nickel-Alloy 718 Forged Bar, Inconel 718 Round Bar, Inconel 718 rod, W.Nr.2.4668 round bar
INCONEL® alloy 718 (UNS N07718/W.Nr. 2.4668) is a high-strength, corrosion-
inconel alloy 718 hex bolt has a good overall performance in the temperature range of -253 ~ 700 ℃. The yield strength below 650 ℃ ranks first in the deformed superalloy and has good resistance to fatigue, radiation, oxidation and corrosion as well as good Processing performance, good welding performance. Can produce a variety of complex shapes of parts and components, in the aerospace, nuclear energy, petroleum industry and extrusion die, in the above temperature range has been very widely used.
Nickel Alloy 718, frequently called Inconel® 718, is a precipitation hardenable corrosion and heat-resistant nickel alloy available in bars, forgings, sheets and plates.
Applications:
Gas turbine engine parts
Liquid fuel rocket motor components
Springs, fasteners
Cryogenic tanks
ASTM B637 – 18
Standard Specification for Precipitation-Hardening and Cold Worked Nickel Alloy Bars, Forgings, and Forging Stock for Moderate or High Temperature Service
Specifications
| Standards | Designation |
| ASTM | B 637 |
| ASME | SB 637 |
| Standard | Inconel 718 |
| UNS | N07718 |
| Werkstoff Nr. | 2.4668 |
Inconel 718 Round Bar Chemical Composition
| Inconel 718 | |
| Ni | 50 – 55 |
| Fe | Bal |
| Cr | 17 – 21 |
| Cu | 0.3 max |
| Mo | 2.8 – 3.3 |
| Nb | 4.75 – 5.5 |
| C | 0.08 max |
| Mn | 0.35 max |
| P | 0.015 max |
| S | 0.015 max |
| Si | 0.35 max |
| Ti | 0.65 – 1.15 |
| Al | 0.2 – 0.8 |
| Co | 1.0 max |
| B | 0.006 max |
Types of Inconel 718 Round Bars & Wire :
| • | ASTM B 637 Inconel 718 Round Bars |
| • | ASME SB 637 Inconel 718 Rods |
Mechanical Properties (solution + precipitation harden)
| Tensile Strength Rm (Mpa) | Yield Strength Rp0.2 (Mpa) | Elongation % in 2″ (50.8 mm) | Reduction Of Area (%) | Hardness (HBW) |
|---|---|---|---|---|
| 1275 min | 1034 min | 6 min | 8 min | 331 min |
Inconel 718 Round Bar Heating and Pickling:
When Inconel 718 Heat Resistant Alloys is heated care must be taken to maintain both the furnace and the material being heated at correct temperatures.
Fuels used for heating must be extremely low in sulfur. The alloy must be absolutely clean and free from all oil, paint, grease, and shop soil when charged into the furnace.
The furnace atmosphere for forging or open annealing should be slightly reducing, containing at least 2% carbon monoxide. A slight positive pressure should be maintained in the furnace to prevent air infiltration.
When Inconel 718 Heat Resistant Alloys is heated in a reducing atmosphere, a thin, adherent green-black film of oxide will be left on the surface of the material. In oxidizing atmospheres, a heavy black scale is produced that is very difficult to remove.
Every precaution should be taken in heating so that only the green-black film is formed.
Inconel 718 Round Bar Heat Treatment:
For most applications, Inconel 718 Heat Resistant Alloys is specified as: solution annealed and precipitation hardened (precipitation hardening, age hardening, and precipitation heat treatment are synonymous terms).
Inconel 718 Heat Resistant Alloys is hardened by the precipitation of secondary phases (e.g. gamma prime and gamma double-prime) into the metal matrix.
The precipitation of these nickel-(aluminum, titanium, niobium) phases is induced by heat treating in the temperature range of 1100 to 1500°F. For this metallurgical reaction to properly take place, the aging constituents (aluminum, titanium, niobium) must be in solution (dissolved in the matrix); if they are precipitated as some other phase or are combined in some other form, they will not precipitate correctly and the full strength of the alloy with not be realized.
To perform this function, the material must first be solution heat treated (solution annealed is a synonymous term).
Two heat treatments are generally utilized for Inconel 718 Heat Resistant Alloys:
•Solution anneal at 1700-1850°F followed by rapid cooling, usually in water, plus precipitation hardening at 1325°F for 8 hours, furnace cool to 1150°F, hold at 1150°F for a total aging time of 18 hours, followed by air cooling.
•Solution anneal at 1900-1950°F followed by rapid cooling, usually in water, plus precipitation hardening at 1400°F for 10 hours, furnace cool to 1200°F, hold at 1200°F for a total aging time of 20 hours, followed by air cooling.
If the material is to be machined, formed, or welded, it typically is purchased in the mill annealed or stress relieved condition. The material is then fabricated in its most malleable condition. After fabrication, it can be heat treated as required per the applicable specification.
1700°-1850°F Anneal and Age:
The 1700°-1850°F anneal with its corresponding aging treatment as shown earlier is the optimum heat treatment for Inconel 718 Heat Resistant Alloys where a combination of rupture life, notch rupture life and rupture ductility is of greatest concern. The highest room-temperature tensile and yield strengths are also associated with this treatment. In addition, because of the fine grain developed, it produces the highest fatigue
strength.
1900°-1950° Anneal and Age:
The 1900°-1950° anneal with its corresponding aging treatment as shown above is the treatment preferred in tensile-limited applications because it produces the best transverse ductility in heavy sections, impact strength, and low-temperature notch tensile strength. However, this treatment has a tendency to produce notch brittleness in stress rupture.
Other Heat Treatments:
Special Metals produces Inconel 718 for use in oil field applications. This material is produced under the NACE specification MR0175 which requires the solution annealed and aged material to meet a maximum hardness value of 40 Rockwell “C”. Such material is typically solution heat treated at 1850-1900 °F and aged at 1450°F for six to eight hours and air cooled. Numerous proprietary heat treatments are used for Inconel 718 depending on the properties required. Such heat treatment sequences are usually developed by companies or agencies independent of the material supplier; consequently, discussion of procedures, tolerances, and resulting properties should be with that company or agency.
CORROSION RESISTANCE:
Inconel 718 Heat Resistant Alloys has excellent corrosion resistance to many media. This resistance, which is similar to that of other nickel-chromium alloys, is a function of its composition. Nickel contributes to corrosion resistance in many inorganic and organic, other than strongly oxidizing, compounds throughout wide ranges of acidity and alkalinity.
It also is useful in combating chloride-ion stress-corrosion cracking. Chromium imparts an ability to withstand attack by oxidizing media and sulfur compounds. Molybdenum is known to contribute to resistance to pitting in many media.
Inconel 718 Round Bar Fabrication Data:
Hot Forming
Because of its strength, Inconel 718 Heat Resistant Alloys is more resistant than most materials to deformation during hot forming. Its relative resistance is shown by pressures developed in the roll gap at 20% reduction. It is readily hot-worked if sufficiently powerful equipment is used.
Hot forming is performed in the 1650°-2050°F temperature range. In the last operation, the metal should be worked uniformly with a gradually decreasing temperature, finishing with some light reduction in the 1650°-1750°F range. This procedure is necessary to ensure notch ductility in stress-rupture applications when material has been annealed and aged. In heating for hot working,
the material should be brought up to temperature, allowed to soak a short time to ensure uniformity, and withdrawn.
To avoid duplex grain structure Inconel 718 should be given uniform reductions. Final reductions of 20% minimum should be used for open-die work and 10% minimum for closed-die work. Parts should generally be aircooled from the hot-working temperature rather than water quenched.
Care should be taken to avoid overheating the metal by heat buildup due to working. Also, the piece should be reheated when any portion has cooled below 1650°F. Preheating tools and dies to 500°F is recommended. Any ruptures appearing on the surface of the workpiece must be removed at once.
Super-Plastic Forming
A special grade of Inconel 718 Heat Resistant Alloys that is specifically designed for the super-plastic forming process is manufactured by Special Metals. This alloy, designated Inconel 718SPF, is available as annealed sheet in thicknesses from 0.02 to 0.08 inches (0.5 to 2.0 mm) in widths up to 36 inches (914 mm). The specification SAE AMS 5950 was developed to define the requirements for the alloy.
Machining
The Heat Resistant Alloys can be readily machined in either the annealed or the age-hardened condition. The age-hardened condition gives better chip action on chip breaker tools and produces a better finish. The annealed condition will give a slightly longer tool life.
Welding
Inconel 718 Heat Resistant Alloys can be welded in either the annealed or the age condition. Welding in the aged condition will cause the formation of a softened heat-affected zone.
Mill′s test certificate:
EN 10204/3.1
