NS333
Material grade: NS333 corrosion-resistant alloy
US grade: UNS N06645
Similar grade: Hastelloy C
German grade: W.Nr.2.4610
1. Overview of NS333 (Hastelloy C, N06645, 2.4610) corrosion-resistant alloy:
1. NS333 is a nickel-chromium-molybdenum alloy containing tungsten, with very low silicon and carbon content. The characteristics of NS333 are:
(1) Excellent corrosion resistance to most corrosive media in both oxidizing and reducing conditions.
(2) Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking.
2. Application fields of NS333 (Hastelloy C, N06645, 2.4610) alloy:
It has been widely used in the chemical and petrochemical fields, such as in components and catalytic systems that come into contact with chlorinated organic substances. This material is particularly suitable for use in high-temperature environments with inorganic and organic acids (such as formic acid and acetic acid) mixed with impurities, as well as in seawater corrosion environments. Other application fields:
(1) Pulp and paper industry, such as cooking and bleaching vessels
(2) Washing towers, reheaters, wet gas fans, etc. in FGD systems
(3) Equipment and components operating in acidic gas environments
(4) Reactors for acetic acid and acidic products
(5) Sulfuric acid condensers
(6) Methylene diphenyl diisocyanate (MDI)
(7) Production and processing of impure phosphoric acid
3. Chemical composition of NS333 (Hastelloy C, N06645, 2.4610) alloy:

4. Physical properties of NS333 (Hastelloy C, N06645, 2.4610) alloy:
(1) Density: ρ=8.9g/cm³      
(2) Melting temperature range: 1325～1370℃
5. Mechanical properties of NS333 (Hastelloy C, N06645, 2.4610) alloy:
The minimum values in the table below are measured data in the longitudinal and transverse directions of standard size specimens (solution-treated state). Special specifications and material properties can be customized according to customer requirements.
6. NS333 (Hastelloy C, N06645, 2.4610) alloy NS333ISO-V notch test:
Average ≥120J/cm², Room temperature ≥120J/cm²-196℃
7. Microstructure of NS333 (Hastelloy C, N06645, 2.4610) alloy:
NS333 has a face-centered cubic lattice structure, and its chemical composition ensures metallurgical stability and resistance to sensitization.
8. Corrosion resistance of NS333 (Hastelloy C, N06645, 2.4610) alloy:
The high molybdenum and chromium content allows NS333 alloy to resist the erosion of various chemical media, including reducing media such as phosphoric acid, hydrochloric acid, sulfuric acid, chlorine gas, and organic or inorganic chlorinated media. Due to the high nickel content, NS333 can effectively resist stress corrosion cracking caused by chlorine, even in hot chlorinated solutions. Time-temperature-sensitization curve (carbon content 0.008%, reference ASTM G28 Method A)

2. Application range of NS333 (Hastelloy C, N06645, 2.4610) corrosion-resistant alloy:
NS333 has been widely used in most chemical fields and high-temperature environments. Typical application fields:
1. Flue gas desulfurization systems
2. Pickling and acid regeneration plants
3. Production of acetic acid and agricultural chemicals
4. Titanium dioxide production (chlorination method)
5. Electrolytic plating
3. Processing and heat treatment of NS333 (Hastelloy C, N06645, 2.4610) corrosion-resistant alloy:
1. Processing characteristics of NS333 (Hastelloy C, N06645, 2.4610) alloy:
(1) NS333 alloy can be manufactured and processed using traditional production processes.
(2) Always keep the workpiece clean and free of contamination before and during heat treatment.
(3) The sensitivity of the alloy to sensitization during rapid cooling from 1000℃ to 600℃ should be fully considered.
(4) During the heat treatment process, contact with sulfur, phosphorus, lead, and other low melting point metals must be avoided, otherwise, the performance of the alloy will be compromised. Attention should be paid to removing contaminants such as marking paint, temperature indicating paint, colored crayons, lubricating oil, and fuel.
(5) The lower the sulfur content in the fuel, the better. The sulfur content in natural gas should be less than 0.1%, and in heavy oil, it should be less than 0.5%.
(6) The furnace gas in the heating furnace should be neutral to slightly oxidizing, and fluctuations between oxidizing and reducing atmospheres should be avoided. The heating flame should not be directed at the workpiece.
2. NS333 (Hastelloy C, N06645, 2.4610) alloy processing heating:
Always keep the workpiece clean and free of contamination before and during heat treatment.
During the heat treatment process, contact with sulfur, phosphorus, lead, and other low melting point metals must be avoided, otherwise, the Nicrofer 6616 hMo alloy will become brittle. Attention should be paid to removing contaminants such as marking paint, temperature indicating paint, colored crayons, lubricating oil, and fuel. The lower the sulfur content in the fuel, the better. The sulfur content in natural gas should be less than 0.1%, and in heavy oil, it should be less than 0.5%. Electric furnace heating is a better choice because it can control the temperature precisely, and the furnace gas is clean. If the gas furnace has sufficiently pure gas, it can also be chosen.
The furnace gas in the heating furnace should be neutral to slightly reducing, and fluctuations between oxidizing and reducing atmospheres should be avoided. The heating flame should not be directed at the workpiece.
3. NS333 (Hastelloy C, N06645, 2.4610) alloy processing hot working:
(1) The hot working temperature range for NS333 is 1200℃ to 950℃, and the cooling method is water cooling or rapid air cooling.
(2) To ensure optimal corrosion resistance, heat treatment should be performed after hot working, and the workpiece should be directly placed into the preheated heat treatment furnace.
4. NS333 (Hastelloy C, N06645, 2.4610) alloy processing cold working:
(1) The work hardening rate of NS333 is greater than that of austenitic stainless steel, so the processing equipment needs to be selected accordingly. The workpiece should be in a solution heat-treated state, and intermediate annealing should be performed during cold rolling.
(2) If the cold rolling deformation exceeds 15%, a secondary solution treatment is required for the workpiece.
5. NS333 (Hastelloy C, N06645, 2.4610) alloy processing heat treatment:
(1) The solution treatment temperature range for NS333 is 1100℃ to 1160℃.
(2) The cooling method is water quenching, and materials with a thickness of less than 1.5mm can also use rapid air cooling. If air cooling is used, it should cool from 1000℃ to 600℃ within 2 minutes.
(3) During the heat treatment process, the workpiece must be kept clean.
6. NS333 (Hastelloy C, N06645, 2.4610) alloy processing descaling:
(1) The adhesion of surface oxides and welding slag around the weld of NS333 is stronger than that of stainless steel, so it is recommended to use fine-grained sandpaper or fine-grained grinding wheels for polishing.
(2) Before pickling with HNO3/HF mixed acid, sandblasting or grinding must be done to break the oxide film.
7. NS333 (Hastelloy C, N06645, 2.4610) alloy processing machining:
Due to sensitivity to work hardening, it is advisable to use low cutting speeds and heavy feed to machine below the cold-work-hardened surface.
8. NS333 (Hastelloy C, N06645, 2.4610) alloy processing welding:
When welding nickel-based materials, the following procedures should be followed:
(1) Work area The work area should be separated or have sufficient distance from the carbon steel processing area, kept as clean as possible, with partitions to avoid ventilation between the two areas.
(2) Clean, fine-grained leather gloves and clean work clothes should be worn.
(3) Tools and machinery should have dedicated tools for nickel-based alloys and nickel-chromium steel. Steel wire brushes should be made of stainless steel, and machines such as shears, punch presses, and rolling mills should be covered with felt, cardboard, or plastic to prevent iron-carbon metals from falling onto the machine surface and causing corrosion.
9. NS333 (Hastelloy C, N06645, 2.4610) alloy processing cleaning:
The materials to be welded should be in a solution-treated state, with oxide scale, oil stains, and various marking residues removed, and the base metal and filler alloy (such as welding rods) in the welding area should be cleaned with acetone. Note that trichloroethylene (TRI), perchloroethylene (PER), and tetrachloride (TETRA) should not be used.
10. NS333 (Hastelloy C, N06645, 2.4610) alloy processing edge preparation:
It is best to use machining, such as turning, milling, or planing. Plasma cutting can also be performed, but if the latter is used, the cutting edge (welding surface) must be ground clean and flat, allowing for no overheating during finishing.
11. NS333 (Hastelloy C, N06645, 2.4610) alloy processing bevel angle:
Compared to carbon steel, the physical properties of nickel-based alloys and special stainless steels are characterized by low thermal conductivity and high expansion coefficients. These characteristics must be considered during the preparation of welding grooves, including widening the bottom gap (1-3mm). Additionally, due to the viscosity of molten metal, a larger groove angle (60-70°) should be used during butt welding to compensate for material shrinkage.
12. NS333 (Hastelloy C, N06645, 2.4610) alloy arc initiation:
Arcing should not be initiated on the workpiece surface, but rather on the welding surface to prevent corrosion at the arcing point.
13. NS333 (Hastelloy C, N06645, 2.4610) alloy welding process:
NS333 is suitable for any traditional welding process, such as tungsten electrode inert gas shielded welding, plasma arc welding, manual submerged arc welding, metal inert gas shielded welding, and flux-cored inert gas shielded welding.
(1) NS333 alloy filler metal: welding rod: ENiCrMo-13, welding wire: ENiCrMo-13
(2) NS333 welding parameters and influences (heat input):
Welding operations should be conducted under specified low heat input, with interlayer temperatures not exceeding 120°C, and using narrow weld bead technology. It is important to correctly select the diameter of the welding wire and rod (please consult our welding laboratory). Based on these principles, welding parameters can be controlled to achieve the heat input per unit length as shown in Table 8.
(3) NS333 post-weld treatment (pickling and removal of oxides):
If there are no special requirements or regulations, pickling is usually the last step in welding, and it is generally performed by specialized factories. If the quality requirements of the workpiece are extremely high, oxides should be removed immediately with a stainless steel brush while the material is still hot after welding. This usually results in an ideal surface condition and thoroughly removes oxides.
4. NS333 (Hastelloy C, N06645, 2.4610) corrosion-resistant alloy varieties, specifications, and supply status:
1. Specifications: NS333 seamless pipes, NS333 steel plates, NS333 round steel, NS333 forgings, NS333 flanges, NS333 rings, NS333 welded pipes, NS333 steel strips, wire NS333 materials, and matching welding materials.
2. Delivery status: Seamless pipes: solution + acid pickled, length can be customized; plates: solution, acid pickled, trimmed; welded pipes: solution acid pickled + RT% flaw detection, forgings: annealed + turned; bars in forged state, surface polished or turned; strips delivered in cold-rolled, solution soft state, and descaled; wires delivered in solution acid pickled coil or straight bar form, solution straight bar finely polished.