Incoloy?825
Material grade: Incoloy?825 Nickel-based alloy
U.S. grade: UNS N08825
Germany grade: ?W.N r.2.4858
Chinese grade: NS142
One, Incoloy825 ( N08825, 2.4858) nickel-based alloy overview and performance:
1, Incoloy825 (N08825, 2.4858) alloy is titanium-stabilized treatment of fully austenitic nickel-iron-chromium alloys, and added copper and molybdenum.
Incoloy825 has the following characteristics:
(1), good resistance to stress corrosion cracking.
(2), good resistance to pitting and crevice corrosion
(3), very good resistance to oxidation and non-oxidizing thermo-acidic properties
(4), very good mechanical properties both at room temperature and at high temperatures up to 550°C
(5), certified to fabricate pressure vessels with temperatures up to 450°C
2, Incoloy825 (N08825, 2.4858) alloy chemical composition: see Table-1
3, Incoloy825 (N08825, 2.4858) alloy physical properties:
(1), Density: ρ = 8.1g/cm3
(2), melting temperature range: 1370 ~ 1400 ℃?
4, Incoloy825 (N08825, 2.4858) alloy mechanical properties:
The properties listed in the following table apply to Incoloy825 alloy specified specifications of the product soft annealed (stabilized annealed) after the situation. Special properties for non-standard size material are available upon request for specific applications.
(1), Room Temperature Mechanical Properties (Minimum):
5. Conditional Stress Values for Incoloy825 (N08825, 2.4858) Alloy:
Higher Conditional Stress Values of up to 90% of the yield strength can be used in applications where slightly larger deformations are allowed. The permanent stresses induced by these stresses result in dimensional changes and are not recommended for flange and sealing gasket connectors.
6, Incoloy825 (N08825, 2.4858) alloy metallographic structure:
Incoloy825 alloy has a stable face-centered cubic structure. The chemical composition and proper heat treatment ensure that corrosion resistance is not weakened by sensitization.
7, Incoloy825 (N08825, 2.4858) alloy corrosion resistance:
Incoloy825 is a general-purpose engineering alloy that is resistant to corrosion by acids and alkali metals in both oxidizing and reducing environments. The high nickel content gives the alloy effective resistance to stress corrosion cracking. Corrosion resistance in a variety of media are very good, such as sulfuric acid, phosphoric acid, nitric acid and organic acids, alkali metals such as sodium hydroxide, potassium hydroxide and hydrochloric acid solution.Incoloy825 higher comprehensive performance in the corrosive media varied nuclear combustion solubilizer, such as sulfuric acid, nitric acid and sodium hydroxide are handled in the same equipment.
Two, Incoloy825 (N08825, 2.4858) alloy applications:
Incoloy825 is widely used in a variety of use temperature does not exceed 550 ℃ industrial areas. Typical applications are:
1, sulfuric acid pickling plant with heating pipes, containers, baskets and chains.
2, seawater cooling heat exchangers, marine products piping systems, acid gas environment piping.
3, heat exchanger, evaporator, washing, impregnation pipe in phosphoric acid production.
4, air heat exchanger in petroleum refining.
5, food engineering.
6, Chemical process.
7, Flame retardant alloys for high pressure oxygen applications.
Three, Incoloy825 (N08825, 2.4858) alloy processing and heat treatment:
Incoloy825 alloy is easy to process in general industrial processes.
1, Incoloy825 (N08825, 2.4858) alloy preheating:
Temperature control is very important to ensure that the corrosion resistance of the alloy is not weakened by sensitization. The workpiece must be surface cleaned before and during heating to keep the surface clean. Nicrofer 6023/6023H alloy will become brittle if the heating environment contains sulfur, phosphorus, lead or other low melting point metals. Impurities come from marking paints, chalk, lubricants, water, fuels, etc. Fuels should have low sulfur content, such as liquefied petroleum gas and natural gas with less than 0.1% impurities, city gas with less than 0.25g/m3, and liquefied petroleum gas with less than 0.5% sulfur is ideal.
Heat treatment is best carried out in a vacuum resistance furnace or inert gas protective atmosphere, because this can control the temperature accurately and free from impurity contamination. If the impurity content of the gas is low, you can also consider the use of gas heating furnace, so that you can get a neutral or weakly oxidizing atmosphere. The composition of the furnace gas should be avoided to fluctuate between oxidizing and reducing, and the combustion flame should not be burned directly to the workpiece.
2, Incoloy825 (N08825, 2.4858) alloy hot working:
Incoloy825 alloy suitable hot working temperature of 1150-900 ℃, the cooling method can be water quenching or rapid air cooling. For hot working, the workpiece can be fed directly into a furnace that has come to temperature. After the furnace is brought to temperature, the material is held for 60 minutes per 100 mm thickness. Immediately after holding to temperature for the specified time, the material is removed from the furnace and processed within the specified temperature range. If the temperature of the metal drops below the minimum processing temperature, it should be heated again. Annealing should be done promptly after thermal processing to ensure that optimum corrosion resistance and a suitable crystal structure are obtained.
3, Incoloy825 (N08825, 2.4858) alloy cold working:
Cold working should be carried out after solution treatment, Incoloy825 work hardening rate and austenitic stainless steel is close to the processing equipment should be adjusted accordingly. There should be an intermediate annealing process when the amount of cold working is large. When the final cold deformation is greater than 15% need final stabilization treatment.
4, Incoloy825 (N08825, 2.4858) alloy heat treatment:
Soft annealing or stabilization of the temperature range of 920-980 ℃, the most suitable for 940 ± 10 ℃. For workpieces greater than 1.5mm thick water quenching or rapid air cooling is recommended to obtain maximum creep resistance. During any heat treatment, attention should be paid to the matters mentioned earlier about keeping clean.
5, Incoloy825 (N08825, 2.4858) alloy grinding and pickling:
Oxides in the vicinity of weld seams on Incoloy825 workpieces are more difficult to remove than those on stainless steel, and need to be polished with a fine abrasive belt or wheel. In order to maintain the luster of the metal, sanding should be done with great care. Oxides should also be removed with sandpaper or pretreated in a salt bath before pickling in a mixture of nitric and hydrofluoric acids. The timing of the pickling should be especially careful.
6, Incoloy825 (N08825, 2.4858) alloy machining:
Incoloy825 machining needs to be carried out after solution treatment, taking into account the work-hardening properties of the material, unlike austenitic stainless steels, low surface cutting speeds and heavy feeds are required.
Four, Incoloy825 (N08825, 2.4858) alloy welding:
1, in the nickel-based alloys for welding, the following procedures should be followed:
(1), the workplace: the workplace should be separate or a sufficient distance from the processing of carbon steel area, as far as possible to maintain clean, with a partition and avoid the two areas between the Ventilation.
(2) Clothing and aids: Clean, fine-grained leather gloves and clean work clothes shall be worn.
(3), tools and machinery and equipment: there should be nickel-based alloy and nickel-chromium steel special tools, wire brushes should be made of stainless steel, machinery and equipment such as shears, punches, mills, etc., should be covered with felt, cardboard or plastic paper in order to prevent ferrous and carbon metals fall on the surface of the machine and make the processing materials to stick to the surface of the machine, resulting in corrosion. Remove oxidized skin, oil and all kinds of marking marks, and use acetone to weld the area of the base metal and filler alloy (such as welding rods) to clean, pay attention to can not use trichloroethylene TRI, perchlorethylene PER and tetrachloroethylene TETRA.
2, Incoloy825 edge preparation: it is best to use machining, such as turning, milling, planing, but also plasma cutting, if the use of the The latter, the cutting edge (welding surface) must be ground clean and flat, allowing for fine grinding without overheating. Weld on both sides of the base metal about 25mm width of the area to be polished to reveal the bright metal.
3, Incoloy825 bevel angle: compared with carbon steel, nickel-based alloys and special stainless steel physical properties are mainly characterized by low thermal conductivity and high coefficient of expansion, these characteristics should be taken into account in the preparation of the weld bevel, including the widening of the bottom gap (1 ~ 3mm), and at the same time due to the viscous nature of the molten metal, in the butt weld should be used to greater bevel angle (60 ~ 70 °) to offset the material. 70°) to offset material shrinkage.
4, Incoloy825 arc: can not arc on the surface of the workpiece, should be in the welding surface arc, in order to prevent the arc point leads to corrosion.
5, Incoloy825 welding process:
(1), Incoloy825 is suitable for the use of any traditional welding process with the same material or other metal welding, such as tungsten electrode inert gas shielded welding, plasma arc welding, manual subarc welding, metal pole inert gas shielded welding, melting pole inert gas shielded welding, of which pulse arc welding is the preferred option. In the use of manual arc welding, it is recommended to use (Ar + He + H2 + CO2) a variety of components mixed shielding gas.
(2), Incoloy825 welding must be carried out in the annealed state, and the use of stainless steel wire brush to clean up stains, dust and various marks. In the weld root welding, in order to get the best root weld quality, the operation must be very careful (argon 99.99), so that the weld does not produce oxides after the root welding. The color produced in the heat affected zone of the weld is to be removed with a stainless steel brush while the weld area is not cooled.
(3), Incoloy825 filler metal: electrode: ENiCrMo-3, wire: ERNiCrMo-3
6, Incoloy825 welding parameters and effects (heat input):
Welding operations should be carried out in the heat input table under the provisions of the low heat input, the use of stacked bead weld technology, the interlayer temperature does not exceeding 120°C. Welding specifications must be observed. Heat input Q is calculated according to the following formula:
7, Incoloy825 post-weld treatment (pickling, brush removal of oxides and heat treatment): welding should be immediately after the use of stainless steel wire brush brush removal of oxides, that is to say, in the metal has not been produced when the color of the weld is brushed so that you can get the desired surface quality without the need for pickling. If not specifically required or specified, pickling is usually the last process in welding, see section on oxide removal and pickling. No heat treatment is required before or after welding.
Heat input per unit length (guide value):
8, Incoloy825 varieties of specifications and supply status:
1, varieties of classifications: special alloys can produce a variety of specifications of Incoloy825 seamless pipe, Incoloy825 steel plate, Incoloy825 round steel, Incoloy825 forgings, Incoloy825 flange, Incoloy825 ring, Incoloy825 welded pipe, Incoloy825 steel strip, Incoloy825 wire and supporting welding consumables.
2, delivery status: seamless pipe: solid solution + acid white, length can be fixed; plate: solid solution, pickling, cutting edge; welded pipe: solid solution acid white + RT% flaw detection, forging: annealing + turning; bar to forging rolled state, surface grinding or turning; strip delivered by cold rolling, solid solution soft state, de-oxidized skin; wire to solid solution pickling disc or straight bar, solid solution straight bar fine grinding state delivery.