What materials can replace Inconel 718
author: www.qishine.com
2025-01-01
Inconel 718 Screw
Overview
Commonly used 718 alloy screws can be divided into two categories according to strength, AMSE specification 718, with a yield strength of 150ksi, and NACE specification 718, with a yield strength of 120ksi.
Overview
Commonly used 718 alloy screws can be divided into two categories according to strength, AMSE specification 718, with a yield strength of 150ksi, and NACE specification 718, with a yield strength of 120ksi.
Alloy 718 is a precipitation-hardenable nickel-based alloy that exhibits high yield strength, tensile strength, and creep cracking strength at temperatures up to 704 °C. Alloy 718 has a slow age-hardening reaction and therefore does not harden with heating and cooling during annealing and welding. Alloy 718 has excellent weldability compared to other nickel-based superalloys with aluminum and titanium additions.
Another characteristic of the alloy is that the alloy structure is particularly sensitive to hot working technology. By understanding the laws of phase precipitation and dissolution in the alloy and the relationship between the structure, process and performance, reasonable and feasible process specifications can be formulated for different use requirements, and various parts that meet different strength levels and use requirements can be obtained. The varieties supplied include forgings, forged bars, rolled bars, cold rolled bars, round cakes, rings, plates, strips, wires, tubes, etc. It can be made into discs, rings, blades, shafts, fasteners and elastic elements, plate structural parts, casings and other parts for long-term use in aviation.
Main Applications of Inconel 718 Alloy
1. Chemical treatment
2. Aerospace
3. Liquid fuel rocket engine components
4. Pollution control equipment
5. Nuclear Reactor
6. Cryogenic storage tank
7. Valves, fasteners, springs, spindles, tubing hangers
8. Wellhead completion equipment and blowout preventers (BOPs)
9. Gas turbine engine parts
In our import and export business, we often encounter different descriptions of the same commodity material due to different standards in different countries, which makes it difficult to find the corresponding product and eventually leads to transaction failure. So today we will talk about the corresponding grades of Inconel 718 alloy in various countries.
Similar grades to 718 alloy:
| China | France | Germany | UK | USA | ISO |
| GH4169, GH169 | NC19FeNb | NiCr19Fe19Nb5, Mo | NA 51 | Inconel 718, UNS NO7718 | NiCr19Nb5Mo3 |
718 alloy physical properties
| Density ρ | 8.24 g/cm3 |
| Melting temperature range | 1260～1320℃ |
Mechanical properties
| Tensile strength | 150ksi or more |
| Yield Strength | 120-145ksi |
| 4D elongation | more than 20% |
| Sectional shrinkage (dia≤10”) | more than 35% |
| Sectional shrinkage (dia＞10”) | more than 25% |
| Hardness | 30-40HRC |
| V-notch impact strength (-59°C or lower) | |
| Average energy | 35ft/lbs (47J) or more |
| Minimum single energy | 30ft/lbs (40J) |
Heat Treatment
1021-1052°C Solution anneal for 1-2.5 hours, then water quench. Bars less than 3.5” in diameter may be water quenched or air cooled. 774-802°C Aged for 6-8 hours, then air cooled.
1021-1052°C Solution anneal for 1-2.5 hours, then water quench. Bars less than 3.5” in diameter may be water quenched or air cooled. 774-802°C Aged for 6-8 hours, then air cooled.
Heat treatment generally needs to be carried out by the steel mill or under the guidance of the steel mill.
application
Jet engine and high-speed airframe parts such as wheels, turbine blades, gaskets, high-temperature bolts, fasteners, etc.
Heat Treatment
Method 1: Get the best tensile strength and stress cracking strength
954-982°C, 1 hour, air cool + 718°C, 8 hours, cool to 621°C at 56°C/hour, keep at temperature for 8 hours, then air cool.
Method 1: Get the best tensile strength and stress cracking strength
954-982°C, 1 hour, air cool + 718°C, 8 hours, cool to 621°C at 56°C/hour, keep at temperature for 8 hours, then air cool.
Method 2: Get the best room temperature and low temperature tensile strength
Heat treatment at 1066 °C for 1-2 hours, air cool to +718 °C for 8 hours, cool to 621 °C at 56 °C/hour, keep at temperature for 8 hours, then air cool.
Heat treatment at 1066 °C for 1-2 hours, air cool to +718 °C for 8 hours, cool to 621 °C at 56 °C/hour, keep at temperature for 8 hours, then air cool.
Thermal Processing
The furnace temperature for hot working does not exceed 1121 °C. If the working temperature is below 593 °C, the temperature range of cold working is controlled within 927-1010 °C, which can provide forging strength. Avoid long-term heating in the furnace during forging.
The furnace temperature for hot working does not exceed 1121 °C. If the working temperature is below 593 °C, the temperature range of cold working is controlled within 927-1010 °C, which can provide forging strength. Avoid long-term heating in the furnace during forging.
Both annealed and age-hardened states can be machined. Age-hardened states are easier to cut and have a better surface finish. For annealed materials, the tool life is slightly longer when machining.
Welding
Alloy 718 can be welded in both the annealed and aged states. When welding aged material, the softened areas will deform due to the heat of the weld.
Inconel 718 alloy is a US standard grade, and the corresponding Chinese grade is GH4169. It seems that GH4169 can replace inconel 718. Let's compare the chemical composition of these two steels.
Inconel 718 Chemical Composition
| Ni | Cr | Fe | C | Mn | Mo | Cu | Co | Al | Ti | Nb | B | P | S | |
| Min | 50 | 17 | Balance | 2.8 | 0.2 | 0.65 | 4.75 | |||||||
| MAX | 55 | 21 | 0.08 | 0.35 | 3.3 | 0.3 | 1.0 | 0.8 | 1.15 | 5.50 | 0.006 | 0.01 | 0.01 |
GH4169 Chemical Composition
| Ni | Cr | Fe | C | Mn | Si | Mo | Cu | Co | Al | Ti | Nb | B | P | S | |
| Min | 50.0 | 17.0 | balance | 2.80 | 0.30 | 0.75 | 4.75 | ||||||||
| MAX | 55.0 | 21.0 | 0.08 | 0.35 | 0.35 | 3.30 | 0.30 | 1.0 | 0.70 | 1.15 | 5.50 | 0.006 | 0.015 | 0.015 |
It is not difficult to see from the chemical composition data of these two steels that their compositions are basically the same, so the domestic grade GH4169 can replace inconel 718 alloy.
【Supply Products】 Inconel 718 screws, bolts, nuts and other fasteners, Inconel 718 bars, Inconel 718 pipes
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