What is the difference between Inconel 625 and Inconel 718?

What is the difference between Inconel 625 and Inconel 718?



 

The difference between Inconel 625 and Inconel 718 is the material composition and use.

inconel 718 is a precipitation-strengthened nickel-based high-temperature alloy material.

Similar brands: GH4169, GH169 (China), NC19FeNb (France), NiCr19Fe19Nb5Mo3 (Germany), NA 51 (UK) Inconel718, UNS NO7718 (USA) NiCr19Nb5Mo3 (ISO)

Inconel718 (N07718) nickel-based alloy
Inconel718 alloy is a precipitation hardening nickel-chromium iron alloy containing niobium and molybdenum. It has high strength, good toughness below 650°C, and corrosion resistance in high and low temperature environments. The delivery state can be solution treated or precipitation hardened.

An overview has the following properties

●Easy processability

●Has high tensile strength, fatigue strength, creep resistance and fracture strength at 700℃

●High oxidation resistance at 1000℃

●Stable chemical properties at low temperatures

●Good welding performance

Application areas

Due to its high temperature strength, excellent corrosion resistance and easy processability at 700°C, it can be widely used in various high-demand situations. ●Steam turbine ●Liquid fuel rocket

●Cryogenic engineering

●Acidic environment

●Nuclear engineering

Physical property density

Density ρ=8.24g/cm3

Melting temperature range

Melting temperature range 1260～1320℃

Processing and heat treatment

Inconel718 alloy is a difficult-to-process material in the field of machining.

preheat

The surface of the workpiece must be cleaned before and during the heating process to keep the surface clean. If the heating environment contains sulfur, phosphorus, lead or other low melting point metals, Inconel718 alloy will become brittle. Impurities come from marking paint, chalk, lubricating oil, water, fuel, etc. The sulfur content of the fuel should be low. For example, the impurity content of liquefied petroleum gas and natural gas should be less than 0.1%, the sulfur content of city gas should be less than 0.25g/m3, and the sulfur content of petroleum gas should be less than 0.5%.

The electric furnace for heating should preferably have a more precise temperature control capability. The furnace gas must be neutral or weakly alkaline, and the furnace gas composition should be prevented from fluctuating in oxidizing and reducing properties.

Thermal processing

The suitable hot processing temperature for Inconel718 alloy is 1120-900°C. The cooling method can be water quenching or other rapid cooling methods. After hot processing, it should be annealed in time to ensure the best performance. During thermal processing, the material should be heated to the upper limit of the processing temperature. In order to ensure the plasticity during processing, the final processing temperature when the deformation reaches 20% should not be lower than 960°C.

Cold working

Cold working should be carried out after solid solution treatment. The work hardening rate of Inconel718 is greater than austenitic stainless steel, so the processing equipment should be adjusted accordingly, and there should be an intermediate annealing process during the cold working process.

heat treatment

Different solution treatment and aging treatment processes will produce different material properties. Due to the low diffusion rate of the γ" phase, Inconel718 alloy can obtain the best mechanical properties through long-term aging treatment.

polish

The oxides near the welds of Inconel718 workpieces are more difficult to remove than those of stainless steel. They need to be polished with a fine abrasive belt. Before pickling in a mixed acid of nitric acid and hydrofluoric acid, the oxides must also be removed with sandpaper or pre-salted in a salt bath. deal with.

machining

The machining of Inconel718 needs to be carried out after solution treatment, and the work hardening of the material must be taken into consideration. Unlike austenitic stainless steel, Inconel718 is suitable for low surface cutting speeds.

welding

The precipitation hardening Inconel718 alloy is very suitable for welding and has no tendency to crack after welding. Weldability, ease of processing, and high strength are the major advantages of this material.

Inconel718 is suitable for arc welding, plasma welding, etc. Before welding, the surface of the material must be clean, free of oil stains, chalk marks, etc., and the 25mm area around the weld must be polished to expose bright metal.

Inconel625 nickel-based alloy

Overview of Inconel625 characteristics and application areas:

This alloy is a solid solution strengthened nickel-based deformed high-temperature alloy with molybdenum and niobium as the main strengthening elements. It has excellent corrosion resistance and high oxidation properties, good tensile properties and fatigue properties from low temperature to 980°C, and is salt resistant. Stress corrosion in fog atmosphere. Therefore, it can be widely used in manufacturing aerospace engine parts, aerospace structural components and chemical equipment.

Inconel625 similar brands:

NS336, GH3625, GH625 (China), NC22DNb (France), W.Nr.2.4856 (Germany), 0Cr20Ni65Mo10Nb4, N06625