Inconel 625 、UNS N06625

Inconel 625 alloy overview:

Inconel 625 is a low-carbon nickel-chromium-molybdenum-niobium alloy with excellent corrosion resistance to various corrosive media. Due to the low carbon content and the stabilization heat treatment, there is still no sensitization tendency even after 50 hours of high temperature holding at 650-900 ° C. The state of delivery is softened and annealed, and its application range includes wet corrosion environments, and has been approved for pressure vessels at temperatures ranging from -196 to 450 ° C. Another performance adjustment is suitable for high temperature applications. Mechanical properties can be improved by age hardening.

 

Inconel 625 chemical composition:

%	Ni	Cr	Mo	Nb+Ta	Fe	Al	Ta	C	Mn	Si	Cu	P	S	Co
Min.	58	20	8	3.15
Max.		23	10	4.15	5	0.4	0.4	0.1	0.5	0.5	0.5	0.015	0.015	1

 

Inconel 625 physical properties:

Density	8.4 g/cm3
Melting point	1290-1350 ℃

 

Minimum value of mechanical properties of Inconel 625 alloy at normal temperature

tensile strength Rm N/mm2	yield strength RP0.2N/mm2	Elongation A5 %	Brinell hardness HB
760	345	30	≤220

 

Inconel 625 alloy has the following characteristics:

1.Excellent corrosion resistance to various corrosive media in oxidizing and reducing environment

2.Excellent resistance to pitting and crevice corrosion, and will not cause stress corrosion cracking due to chloride

3. Excellent resistance to inorganic acid corrosion, such as nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid and mixed acids of sulfuric acid and hydrochloric acid, etc.

4.Excellent resistance to various inorganic acid mixed solutions

5. When the temperature reaches 40 ℃, it can show good corrosion resistance in various concentrations of hydrochloric acid solution.

6.Good processability and weldability, no cracking sensitivity after welding

7. Manufacturing certification of pressure vessels with wall temperature of -196 ～ 450 ℃

8. Certified by the American Society of Corrosion Engineers NACE standard (MR-01-75) to meet the highest standard level VII for use in acid gas environments

 

Inconel 625 metallographic structure

625 is a face-centered cubic lattice structure. When the temperature is maintained at about 650 ° C for a long enough time, carbon particles and unstable quaternary phases will be precipitated and converted into a stable Ni3 (Nb, Ti) orthorhombic lattice phase. After solution strengthening, the molybdenum and niobium components in the nickel-chromium matrix will improve the mechanical properties of the material, but the plasticity will be reduced.

 

Inconel 625 corrosion resistance

Alloy 625 shows excellent corrosion resistance in many media. Excellent resistance to pitting, crevice corrosion, intergranular corrosion and erosion in chloride media. It has good resistance to inorganic acid corrosion, such as nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, etc. At the same time, it also has alkali and organic acid corrosion resistance in the oxidation and reduction environment. Effective resistance to chloride-reducing stress corrosion cracking. It produces almost no corrosion in seawater and industrial gas environments, and has high corrosion resistance to seawater and salt solutions, even at high temperatures. No sensitivity during welding. Resistant to carbonization and oxidation in static or cyclic environments, and resistant to corrosion by chlorine-containing gases.

 

Inconel 625 application areas are:

The softened and annealed low carbon alloy 625 is widely used in the chemical process industry. Its good corrosion resistance and high strength make it a thinner structural component. 625 alloy can be used in places that are exposed to seawater and subjected to high mechanical stress.

 

Typical application areas:

1. Chlorinated organic chemical process components, especially when using acid chloride catalysts

2. digesters and bleaching tanks for the pulp and paper industry

3. Absorption tower, reheater, flue gas inlet baffle, fan (wet), agitator, deflector and flue in the flue gas desulfurization system

4. Equipment and components used in the manufacture of sour gas environments

5.Acid and acetic anhydride reaction generator

6. Sulfuric acid condenser

 

Inconel 625 welding

Suitable for welding by any traditional welding process, such as tungsten electrode inert gas shielded welding, plasma arc welding, manual sub-arc welding, metal extremely inert gas shielded welding, and molten extremely inert gas shielded welding.

The material to be welded should be in the solution treatment state to remove oxide scale, oil stains and various marks. The welding operation should be performed under the specified low heat input, and the interlayer temperature should not exceed 150 ° C. No heat treatment is required before or after welding.