Nickel-chromium alloy (Inconel600, ALLOY600, UNS N06600) and its characteristics

Nickel-chromium alloy (Inconel600, ALLOY600, UNS N06600) and its characteristics
Inconel 600, Inconel alloy

Alloy 600 is a nickel-chromium-iron based solid solution strengthened alloy with good high temperature corrosion resistance and oxidation resistance, excellent cold and hot processing and welding process performance, and satisfactory thermal strength and high plasticity below 700°C. The alloy can be strengthened by cold working, and can also be connected by resistance welding, fusion welding or brazing.

Corresponding brands at home and abroad:

chemical composition:

Physical properties:

Minimum mechanical properties of Inconel 600 alloy at room temperature:

Mechanical properties (room temperature)

characteristic:

1. Good resistance to corrosion by reducing, oxidizing and nitriding media
. 2. Good resistance to stress corrosion cracking at room temperature and high temperature.
3. Good resistance to dry chlorine and hydrogen chloride gas corrosion
. 4. Good mechanical properties at sub-zero, room temperature and high temperature.
5. Good creep rupture strength, recommended for use in working environments above 700°C.

Metallographic structure:
Inconel 600 has a face-centered cubic lattice structure.

Corrosion resistance:
Alloy 600 is corrosion resistant to a variety of corrosive media. The chromium content makes the alloy more corrosion resistant than nickel 99.2 (alloy 200) and nickel 99.2 (alloy 201, low carbon) under oxidizing conditions. At the same time, the higher nickel content makes the alloy very corrosion resistant in reducing conditions and alkaline solutions, and can effectively prevent chlorine-iron stress corrosion cracking. Alloy 600 has very good corrosion resistance in organic acids such as acetic acid, acetic acid, formic acid, and stearic acid, and has moderate corrosion resistance in inorganic acids. It has excellent corrosion resistance in high-purity water used in primary and secondary cycles in nuclear reactors. The particularly outstanding performance of 600 is its ability to resist corrosion from dry chlorine and hydrogen chloride, with an application temperature of 650°C. At high temperatures, the annealed and solution treated alloys have good oxidation resistance and high strength in air. The alloy can also resist ammonia and nitriding and carburizing atmospheres, but when the redox conditions change alternately, the alloy will be corroded by some oxidizing media (such as green dead liquid)

Process performance and requirements: Hot working
1. The hot working temperature range is 1200℃～900℃, and the cooling method is water quenching or rapid air cooling.
2. To obtain the best corrosion resistance and the most suitable crystal structure, heat treatment must be performed after hot working.
3. The material can be directly fed into the heated furnace.

Cold working
1. The cold working material should be annealed or solution heat treated. The work hardening rate of 600 alloy is close to that of austenitic stainless steel, so similar processing equipment can be selected.
2. Intermediate annealing should be performed during the cold working process.
3. When the cold working amount is greater than 5%, the workpiece needs to be solution treated.
4. In order to reduce material wear, the mold should be made of alloy tool steel, cemented carbide or cast steel.

Welding process
The alloy has good welding performance and can be connected by various methods such as arc welding, argon arc welding, resistance welding and brazing. Large or complex welded structures should be annealed at 870℃ for 1h after fusion welding to eliminate welding stress.

Parts heat treatment process
The heat treatment process of parts should be carried out according to the heat treatment system of the corresponding material standard. The annealing treatment of thin plate and strip parts should be carried out in a protective atmosphere.

Inconel 600 application range:
1. Thermocouple sleeves in corrosive atmospheres
2. Vinyl chloride monomer production: resistance to chlorine, hydrogen chloride, oxidation and carbonization corrosion
3. Uranium oxidation conversion to hexafluoride: resistance to hydrogen fluoride corrosion
4. Production and use of corrosive alkali metals, especially in environments using sulfides
5. Chlorine method for titanium dioxide
6. Production of organic or inorganic chlorides and fluorides: resistance to chlorine and fluorine corrosion
7. Nuclear reactors
8. Retorts and components in heat treatment furnaces, especially in carbonization and nitriding atmospheres
9. Catalytic regenerators in petrochemical production Alloy 600 is recommended for applications above 700°C to obtain a longer service life.
This alloy has the performance characteristics of corrosion resistance, heat resistance, oxidation resistance, easy processing and welding

Corrosion resistance
UNS N06600 alloy has excellent corrosion resistance in the atmosphere, water and steam media, and also has good corrosion resistance in some weak acids, dilute oxidizing and reducing acids. In various weak organic acids, the corrosion rate is also very low. For example: in acetic acid at room temperature, the corrosion rate is 0.0025-0.1mm/a. This alloy is particularly resistant to alkali corrosion, such as in NaOH, the NaOH concentration can reach 80%. When there are sulfides in NaOH, its corrosion resistance is better than pure nickel. In the test of 150℃ sodium sulfide, the annual corrosion rate is 0.1mm. It is also resistant to corrosion by various neutral and caustic salts. In some strong acids, the corrosion resistance of UNS N06600 alloy is poor, such as in H3PO4, H2SO4, it can only be used under room temperature conditions; in hydrochloric acid and hydrofluoric acid, it can only be used under very dilute concentration conditions; dry chlorine and dry hydrogen chloride at room temperature do not corrode UNS N06600, but it can only be used in ≤550℃ HF gas at high temperature.

Product Application
This alloy has the comprehensive properties of toughness and corrosion resistance, and is widely used in chemical and other industries. For example, it is used to manufacture heaters, heat exchangers, evaporators, distillation kettles, distillation towers, condensers for fatty acid treatment, equipment for treating rosin acid, chemical pumps, etc. Since the alloy also has high strength and good oxidation resistance at high temperatures, it can also be used in the heat treatment industry to manufacture various structural parts. In the nuclear power industry, the alloy has good corrosion resistance to high temperature and high pressure water, so it is also an important structural material for light water reactor nuclear power plants. The products include plates, rods, wires, strips, and pipes.