The spheroidization of secondary carbides and eutectic steel carbides is related to the forging process. In order to obtain a uniform distribution of granular carbides after annealing, the forged structure should be fine flake pearlite and fine, intermittent network carbides (or containing a small amount of martensite). For this purpose, lower temperatures and shorter times can be used for spheroidization annealing. The lower the annealing temperature and the greater the number of undissolved carbides, it is easy to obtain a uniformly distributed fine-grained pearlite structure. In order to obtain a good spheroidized structure, the forging process must be strictly controlled.
According to Ref. [6], spheroidization annealing heating temperature.
Spheroidization annealing: heated to slightly higher than AC1, slowly cooled to below 500 air cooling after long-term heat preservation;
Periodic (cycle) spheroidization annealing: heating to AC1+10-20, fast cooling to AR1-20 30 heat preservation after overburning, slow cooling to air cooling below 500 after several reciprocating cycles;
Isothermal spheroidization annealing: heating to AC1+20-30, and then fast cooling to isothermal insulation below AR1, and then air cooling or furnace cooling.
alloy 59
Material Grade:alloy 59 nickel basealloys
U.S. Grade:unsn06059
German grade: 24605
1. Overview of Alloy 59 (N06059) nickel-based alloys
Alloy 59 (N06059) nickel-based alloy is a nickel-chromium-molybdenum alloy with very low silicon and carbon content, excellent corrosion resistance and extremely high mechanical strength. Alloy 59 (N06059) also has the following properties:
1. Excellent resistance to pitting corrosion, crevice corrosion and stress corrosion cracking caused by chloride.
2. It has excellent corrosion resistance to inorganic acids, such as nitric acid, phosphoric acid, sulfuric acid and hydrochloric acid, especially for the mixing of sulfuric acid and hydrochloric acid.
3. Excellent resistance to corrosion of various inorganic acid mixed solutions.
4. It has good corrosion resistance in hydrochloric acid solutions of various concentrations up to 40 (104).
5. It has good machinability and weldability, and no post-welding cracking susceptibility.
6. Manufacturing certification of pressure vessels with wall temperature in -196 450.
7. It has been certified by the NACE standard of the American Society of Corrosion Engineers (MR-01-75) to meet the highest standard level VII for use in sour gas environments.
2. Chemical composition of Alloy 59 (N06059) nickel-based alloy: see Table -1:
Table-1
3. Mechanical properties of alloy 59 (N06059) nickel-based alloy:
1. Alloy 59 (N06059) nickel-based alloy density: 86g/cm3
2. Alloy 59 (N06059) nickel-based alloy melting point: 1310-1360
3. Alloy 59 (N06059) nickel-based alloy tensile strength: 02 690MPa,4、Alloy 59(N06059)Yield strength of nickel-based alloys: B 340MPa,5、Alloy 59(N06059)Nickel-based alloy elongation:δ 40,4、Alloy 59(N06059)Nickel-based alloy corrosion resistance:
1. Alloy 59 (N06059) nickel-based alloy has very low carbon and silicon content, and there is no tendency for impurity phase precipitation during hot processing and welding, so it is suitable for various chemical process industries containing oxidizing and reducing media. The high molybdenum and chromium content makes the alloy resistant to chloride ions.
2. The performance of Alloy 59 (N06059) nickel-based alloy is higher than that of other Ni-Cr-Mo stainless steels in most of the standard corrosion tests in oxidizing environments. Alloy 59 (N06059) nickel-based alloys have a corrosion rate more than three times lower than conventional Ni-Cr-Mo stainless steel in some reducing environments (e.g., boiling 10% sulfuric acid) and are also suitable for use in chemical process industries in reducing environments. Alloy 59 (N06059) nickel-based alloy has excellent corrosion resistance in hydrochloric acid.
3. Alloy 59 (N06059) nickel-based alloy material can only have the best corrosion resistance when it is in a suitable metallographic state and pure crystal structure.
5. Alloy 59 (N06059) nickel-based alloy processing and heat treatment
Alloy 59 (N06059) nickel-based alloy has good cold and hot working and machinability.
1. Heating: 1) The workpiece should always be kept clean and pollution-free before and during heat treatment.
2) In the heat treatment process, do not contact sulfur, phosphorus, lead and other low melting point metals, otherwise it will damage the performance of Alloy 59 (N06059) alloy, and attention should be paid to removing dirt such as marking paint, temperature indicator paint, colored crayons, lubricating oil, fuel, etc.
3) The lower the sulfur content in the fuel, the better, and the sulfur content in natural gas should be less than 01%, the sulfur content in heavy oil should be less than 05%。
4) Considering the need for temperature control and keeping clean, it is best to carry out heat treatment in a vacuum furnace or gas shielded furnace.
5), can also be heated in the box furnace or gas furnace, but the furnace gas must be clean and neutral to slightly oxidized is appropriate, should avoid the fluctuation of furnace gas between oxidation and reduction, heating flame can not be directly burned to the workpiece.
2. Thermal processing:
1) The hot working temperature range of Alloy 59 (N06059) alloy is 1180 950, and the cooling method is water cooling or rapid air cooling.
2) In order to ensure the best anti-corrosion performance, heat treatment should be carried out after heat processing, and the workpiece should be directly added to the heat treatment furnace that has been heated.
3. Cold working:
1) The work hardening rate of Alloy 59 (N06059) alloy is greater than that of austenitic stainless steel, so it is necessary to select the processing equipment. The workpiece should be annealed, and there should be intermediate annealing during the cold rolling process.
2) If the deformation of cold rolling is greater than 15%, the workpiece needs to be solution treated.
4. Heat treatment
1) The solution treatment temperature range of Alloy 59 (N06059) alloy is 1100 1180.
2), for thickness less than 1The 5mm material is recommended to be cooled by water quenching or rapid air cooling to ensure the best corrosion resistance.
3) In all heat treatment processes, the workpiece should be directly added to the heated heat treatment furnace, and the workpiece must be kept clean.
5. Descaling:
1) The adhesion of the surface oxide and welding slag around the weld of alloy 59 (N06059) alloy is stronger than that of stainless steel, and it is recommended to use fine-grained abrasive belt or fine-grained grinding wheel for grinding.
2) Before pickling with Hno3 HF mixed acid at the appropriate time and temperature, the oxide film must be carefully sanded or pretreated in a salt bath.
6. Machining: Alloy 59 (N06059) alloy should be machined after heat treatment, due to the work hardening of the material, it is advisable to use a lower cutting speed and refeed than the machining of low-alloy standard austenitic stainless steel for processing, in order to turn into the surface layer that has been cold work hardening.
7. Suggestions for welding: When welding nickel-based materials, the following procedures should be followed:
1) Workplace The workplace should be separated separately or at a sufficient distance from the carbon steel processing area, kept as clean as possible, with partitions and avoiding ventilation between the two areas.
2) Work clothes and auxiliary supplies should wear clean fine-grained leather gloves and clean work clothes.
3) Tools and machinery and equipment should have special tools for nickel-based alloys and nickel-chromium steel, wire brushes should be made of stainless steel materials, and machinery and equipment such as shearing machines, punches, rolling mills, etc. should be covered with felt, cardboard or plastic paper to prevent iron and carbon metal from falling on the surface of the machine and making the processed materials stick, resulting in corrosion.
8. Cleaning: The material to be welded should be in a solution treatment state, remove oxide scale, oil stains and various marking marks, and clean the base metal and filling alloy (such as welding rod) in the welding area with acetone, and note that trichloroethylene tri, perchloroethylene per and tetrachloride tetrachloride can not be used.
9. Edge preparation: it is best to use machining, such as turning, milling, planing, plasma cutting can also be carried out, if the latter is used, the cutting edge (welding surface) must be ground clean and flat, and fine grinding without heat is allowed.
10. Bevel angle: Compared with carbon steel, the physical properties of nickel-based alloys and special stainless steels are mainly characterized by low thermal conductivity and high expansion coefficient, which should be considered in the preparation of welding bevels, including widening the bottom gap (1 3mm), and at the same time, due to the viscosity of molten metal, a larger groove angle (60 70 °) should be used in butt welding to offset the shrinkage of the material.
11. Arc starting: The arc should be started in the welding area of the workpiece, that is, on the welding surface, so as to prevent corrosion caused by the arc starting point.
12. Welding process: Alloy 59 (N06059) alloy can be welded with the same material or other metals, and is suitable for welding by any traditional welding process, such as tungsten electrode inert gas shielded welding, plasma arc welding, manual sub-arc welding, metal pole inert gas shielded welding, melting pole inert gas shielded welding, and pulse sub-arc welding technology is preferred. When using manual arc welding, it is recommended to use a mixed shielding gas with AR+HE+H2+CO2 composition.
13. Filler metal: For gas shielded welding, it is recommended to use welding rods with the same chemical composition as the base material. Commonly used welding wire: Ernicrmo-13 Coating electrode: EniCRMO-13.
6. Application range of Alloy 59 (N06059) nickel-based alloy:
Alloy 59 (N06059) alloy has a wide range of applications in the fields of chemistry, petrochemical, energy manufacturing and pollution control, and typical applications are as follows:
1. Especially when using acid chloride catalysts. 2. Digesters and bleaching equipment in the pulp and paper industry. 3. Scrubbers, reheaters, throttle valves, wet steam fans and agitators in FGD and IG systems. 4. Equipment and components operating in an acidic gas environment. 5. Reactor for acetic acid and acetic anhydride products. 6. Sulfuric acid condenser.
7. Alloy 59 (N06059) nickel-based alloy variety, specification and state:
1. Variety classification: special alloys can produce various specifications of alloy 59 seamless pipes, alloy 59 steel plates, alloy 59 round bars, alloy 59 forgings, alloy 59 flanges, alloy 59 rings, alloy 59 welded pipes, alloy 59 steel strips, alloy 59 wires and alloy 59 supporting welding consumables.
2. Delivery status: seamless tube: solid solution + acid white, the length can be fixed;Plates: solution, pickling, trimming;Welded pipe: solid solution acid white + RT% flaw detection, forgings: annealing + turning light;The bar is in a forged, surface-polished or turned state;The strip is delivered cold-rolled, solution-soft and descaledThe filaments are delivered in solution pickled discs or straight strips, solution straight strips in finely polished condition.