Nickel alloys 59

Alloy 59, developed by ThyssenKrupp VDM GmbH, is a nickel-chromium-molybdenum alloy with a very lower carbon and silicon content. Alloy 59 has excellent corrosion resistance to wide range of corrosive media and high mechanical strength, so widely used in an assortment of harsh environments.

Chemical Composition (wt. %)

Main Features

1. Outstanding resistance to a wide range of corrosive media under oxidizing and reducing conditions.
2. Excellent resistance to pitting and crevice corrosion from chloride-induced stress corrosion cracking.
3. Excellent resistance to mineral acids, such as nitric, phosphoric, sulfuric  acid, hydrochloric acids and in particular their mixtures.
4. Excellent resistance to contaminated mineral acids.
5. Good corrosion resistant to hydrochloric acid over the whole concentration range up to 104°F (40°C).
6. Chemically stable, low susceptibility against intergranular corrosion.

Main Applications

1. Chemical industry: components in chemical processes involving chlorides, particular when acid chloride catalysts are employed; reactors for acetic acid and acetic anhydride; sulfuric acid cooler etc.
2. FGD system: Scrubbers, heat exchangers, dampers, wet fans and spraying systems for flue gas desulfurization (FGD) in coal-fired power stations and waste incineration plants.
3. Pulp & paper: digesters and bleaching plants.
4. Oil & gas: equipment and components in sour gas service.

Fabrication and Heat Treatment

Alloy 59 can be readily formed using various cold and hot working processes.
Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 59 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG and MAG-Tandem) and SMAW (MMA). Pulsed arc welding is the preferred technique. For the MAG processes, the use of a multi-component shielding gas (Ar+He+H2+CO2) is recommended.
For welding, alloy59 should be in the annealed condition and be free from scale, grease and markings.

Nickel alloys 330

Alloy 330 is an austenitic nickel-iron-chromium alloy developed to provide excellent resistance to carburizing and oxidizing atmospheres at elevated temperatures.

Chemical Composition (wt. %)

Main Features

1. Oxidation resistance to 2100°F (1148°C).
2. Resistant to carburization and nitriding.
3. Optimal microstructure to withstand repeated thermal cycling.
4. Good strength at elevated temperature.
5. Metallurgical stability: remains fully austenitic at all temperatures and is not subject to embrittlement from sigma formation.

Main Applications

1. Chemical and Petrochemical Processing: Cracked ammonia components / Petrochemical furnace parts / Petrochemical waste remediation units / Heat exchangers / Flares.
2. Ore Processing: Perlite systems and equipment.
3. Power Generation: Boiler fixtures / Gas turbine components.
4. Thermal Processing: Heat-treat furnace containers / Heat-treat furnace components / High temperature fans / Salt pots.

Fabrication and Heat Treatment

Alloy 330 can be readily formed using various cold and hot working processes.
Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 330 can be readily welded to a variety of dissimilar metals by GTAW, SMAW, and plasma arc processes. For optimum corrosion resistance GTAW is preferred. Prior to welding, the material should be in the annealed condition.

Nickel alloys 400

Alloy 400 is a single-phase solid-solution nickel-copper alloy that offers superior resistance to many corrosive environments over a temperature range from subzero to 800°F (426°C).

Chemical Composition (wt. %)

Main Features

1. Corrosion resistance in a wide range of marine and chemical environments.
2. Freedom from chloride induced stress-corrosion cracking.
3. Good mechanical properties from sub-zero temperatures up to about 550 °C (1020 °F).
4. Good workability and weldability.

Main Applications

1. Alloy 400 has been widely used in marine and chemical processing industries etc.
2. Marine industry: valves, pumps, propeller shafts; marine fixtures and fasteners; electrical and electronic components; springs; brine heaters and evaporator bodies in seawater desalination plants etc.
3. Chemical industry: chemical processing equipment; gasoline and fresh water tanks; crude petroleum stills, process vessels and piping; boiler feed water heaters and heat exchangers; deaerating heaters; sulphuric and hydrofluoric acid alkylation plants etc.
4. Feed-water and steam generator tubing in power plants.
5. Plants for uranium refining and isotope separation in the production of nuclear.

Fabrication and Heat Treatment

Alloy 400 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 400 can be joined to itself and to many other metals by conventional welding processes. These include conventional or hot wire GTAW (TIG), plasma arc, GMAW (MIG/MAG) and SMAW (MMA). Pulsed arc welding is the preferred technique. For the MAG processes the use of a multi-component shielding gas (Ar+He+H2+CO2) is recommended.

For welding, alloy400 should be in the soft-annealed or stress relieved condition and be free from scale, grease and markings.

Nickel alloys 600

Alloy 600 is nickel-chromium-iron alloy with excellent carburization and good oxidation resistance at elevated temperatures.

Chemical Composition (wt. %)

Main Features

1. Resistant to a wide range of corrosive media under oxidizing conditions. Its oxidation resistance is up to 2000°F (1093°C).
2. Good corrosion resistance under reducing conditions and in alkaline solutions due to Its high nickel content.
3. Particularly resistant to attack by dry chlorine or hydrogen chloride up to 1200 °F (650 °C).
4. Good resistance to chloride stress corrosion cracking.
5. Good resistance to carburization.

Main Applications

1. Heat treatment furnace retorts, furnace belts and components.
2. The production of vinylchloride monomer.
3. The conversion of uranium oxide to hexafluoride.
4. The roduction of caustic alkalis, particularly in the presence of sulphur compounds.
5. The production of titanium dioxide by the chlorine route.
6. The production of organic and inorganic chlorinated and fluorinated compounds.
7. Nuclear reactor components
8. Catalyst regenerators in petrochemical production.

Fabrication and Heat Treatment

Alloy600 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy600 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG) and SMAW(MMA). Pulsed arc welding is the preferred technique. For the MAG process the use of a multi-component shielding gas(Ar+He+H2+CO2) is recommended. For welding, alloy600 should be in the annealed  condition and be free from scale, grease and marks.

Nickel alloys 601H

Alloy 601H is a solid solution strengthened nickel-chromium-iron alloy with additions of aluminium and titanium.

Chemical Composition (wt. %)

Main Features

1. Outstanding resistance to oxidation up to 2200°F (1204°C).
2. Good resistance to carburizing conditions.
3. Good mechanical properties at both room and elevated temperatures.
4. Good resistance to stress-corrosion cracking.
5. Metallurgical stability.

Main Applications

1. Heat treatment furnace muffles and components, such as trays, baskets and fixtures.
2. Oxygen pre-heaters in titanium dioxide production (chloride route).
3. Insulating cans in ammonia reformers and catalyst support grids in nitric acid production.
4. Combustion chambers in solid waste incineration, components of waste gas detoxification systems, tube supports and ash handling components.
5. Industrial gas turbine components, components in exhaust gas systems, flare stack tips and furnace rollers for ceramic tile production;
6. Radiant heater tubes for the heating of annealing furnaces.

Fabrication and Heat Treatment

Alloy 601H can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 601H can be welded by the welding processes GTAW (TIG), plasma arc, GMAW (MAG) and SMAW (MMA). For the MAG process, the use of the shielding gas Cronigon HT is recommended.

For welding, alloy601HH should be in the solution-annealed condition and be free from scale, grease and markings.

Nickel alloys 617

Alloy 617 is a nickel-chromium-cobalt-molybdenum alloy with an exceptional combination of metallurgical stability, strength, and oxidation resistance at high temperatures and excellent cyclic oxidation and carburization resistance up to 2000° F due to solid solution hardening.

Chemical Composition (wt. %)

Main Features

1. Excellent oxidation and carburization resistance up to 2000° F (1100°C).
2. Optimum high-temperature mechanical stability and good stress-rupture properties above1800° F (982°C).
3. Excellent resistance to general corrosion, pitting, crevice corrosion.
4. Good weldability.

Main Applications

1. Aerospace and engine components, such as combustion cans, housings, turbine rings, and other parts exposed to high temperatures.
2. Furnace components, such as muffles, radiant heater tubers etc.
3. High temperature heat exchangers, valves and springs.
4. Equipment in chemical processing, such as production equipment of styrene.
5. Pigtails and furnace tubing in petrochemical industry.
6. High temperature gas-cooled nuclear reactor.

Fabrication and Heat Treatment

Alloy 617 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 617 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG), electron beam welding and SMAW(MMA). Pulsed arc welding is the preferred technique.

For welding, alloy 617 should be in the annealed condition and be free from scale, grease and markings.

Nickel alloys 625

Alloy 625 is a low carbon nickel-chromium-molybdenum-niobium alloy which shows excellent resistance to a variety of corrosive media.

Chemical Composition (wt. %)

Main Features

1. Outstanding resistance to pitting, crevice corrosion, erosion and intergranular attack.
2. Excellent resistance to chloride-induced stress corrosion cracking.
3. Good resistant to mineral acids, such as nitric, phosphoric, sulfuric and hydrochloric acids.
4. Good resistance to alkalis and organic acids.
5. Good mechanical properties, especially good for making thin-walled components with good heat transfer

Main Applications

1. Processing of phosphate ores with high content of impurities and salt crystallization from brines.
2. Aircraft ducting system, engine exhaust systems, turbine shroud rings.
3. Bellow and expansion joints.
4. Flare components.
5. Chemical process equipment handling mixed acids both oxidizing and reducing.

Fabrication and Heat Treatment

Alloy 625 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 625 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG and MAG-Tandem), SAW and SMAW(MMA). Pulsed arc welding is the preferred technique. For the MAG processes the use of a multi-component shielding gas(Ar+He+H2+CO2) is recommended. For welding, Alloy 625 should be in the annealed condition and be free from scale, grease and marks.

Nickel alloys 800H

Alloy 800H is an austenitic high-strength solid-solution nickel-iron-chromium alloy designed for high temperature structure applications. Alloy 800HT has controlled levels of carbon, aluminium, titanium, silicon and manganese and controlled content of (Al + Ti).

Chemical Composition (wt. %)

Main Features

1. Excellent resistance to carburizing, oxidizing and nitriding atmospheres and is used for service temperatures of 600 to 950° C(1,112 to 1,742° F).
2. Metallurgical stability in long-term application at high temperatures.

Main Applications

Alloy 800H is widely used as a material for industrial furnaces and it is the workhorse of the petrochemical industry:

1. Used for the production of pyrolysis tubes in ethylene furnaces.
2. Used for headers and connecting pipes (pigtails) in catalytic hydrocarbon cracking.
3. Used for the components in cracking furnaces producing vinyl chloride, diphenyl and acetic anhydride.
4. Used for transfer lines, valves, fittings and other parts exposed to corrosive attack at temperatures above 600° C (1,112° F).
5. Use for the pipes and tube sheets in styrene production.
6. Used for the burners for burning off reaction products.

Fabrication and Heat Treatment

Alloy 800H can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 800H can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG) and SMAW(MMA). Pulsed arc welding is the preferred technique. For MAG welding the use of a multi-component shielding gas

(Ar+He+H2+CO2) is recommended.

For welding, alloy 800H should be in the solution annealed condition and be free from scale, grease and markings.

Nickel alloys 825

Alloy 825 is a nickel-chromium alloy with additions of molybdenum and copper. It has excellent resistance to both reducing and oxidizing acids, to stress corrosion

cracking, and is especially resistant to sulfuric and phosphoric acids.

Chemical Composition (wt. %)

Main Features

1. Good resistance to stress-corrosion cracking.
2. Satisfactory resistance to pitting and crevice corrosion.
3. Alloy 825 is resistant to sulphuric acid of all concentrations up to a temperature of at least 50 °C. (122 °F).
4. Good resistance to oxidizing and non-oxidizing hot acids.
5. Good mechanical properties at both room and elevated temperatures, up to approximately 550 °C (1020 °F).

Main Applications

1. An ideal material of construction for sulphuric acid heat exchangers, pipes, pickling lines etc.
2. Heat exchangers, evaporators, scrubbers, dip pipes etc. in phosphoric acid production.
3. Air-cooled heat exchangers in petroleum refineries.
4. Sea-water-cooled heat exchangers, offshore product piping systems, tubes and components in sour gas service.
5. Food processing

Fabrication and Heat Treatment

Alloy 825 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

Alloy 825 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG) and SMAW (MMA). Pulsed arc welding is the preferred technique. For the MAG process the use of a multi-component shielding gas (Ar + He + H2 + CO2) is recommended.

For welding, alloy 825 should be in the annealed condition and be free from scale, grease and markings.

Nickel alloys C-276

Alloy C-276 is a nickel-chromium-molybdenum alloy containing tungsten and extremely low carbon and silicon contents. It is characterised excellent corrosion resistance in an assortment of harsh environments.

Chemical Composition (wt. %)

Main Features

1. Excellent resistance to a wide range of corrosive media, under oxidizing and reducing conditions
2. Excellent resistance to pitting, crevice corrosion, and stress corrosion cracking.
3. Sufficient metallurgical (thermal) stability, but should consider its sensitization behavior
4. High strength and ductility

Main Applications

1. Pulp and paper industry, e.g. for digestion and bleaching vessels.
2. Scrubbers and special re-heaters as well as wet-operating fans for combustion and flue gas desulphurisation systems.
3. Equipment and components for sour-gas service.
4. Reactors for acetic acid production.
5. Sulphuric acid coolers.
6. Methylene diphenyl isocyanate (MDI).
7. Manufacture and processing of technically impure phosphoric acid.
8. Combustion-resistant alloy for high pressure oxygen applications.

Fabrication and Heat Treatment

AlloyC-276 can be readily formed using various cold and hot working processes.

Details to see “FABRICATION INSTRUCTIONS FOR HIGH-ALLOYED AUSTENITIC STEELS AND NICKEL ALLOYS”

Welding

AlloyC-276 can be joined to itself and to many other metals by conventional welding processes. These include GTAW (TIG), plasma arc, GMAW (MIG/MAG and MAG-Tandem) and SMAW (MMA). Pulsed arc welding is the preferred technique. For the MAG processes the use of a multi-component shielding gas (Ar+He+H2+CO2) is recommended.

Nickel alloys Fabrication instructions

Fabrication instructions for high-alloyed austenitic steels and nickel alloys

High-alloyed austenitic steels and nickel-base alloys can be worked by all the conventional forming and machining processes. However, they are often more cost-intensive than in the case of the conventional structural steels, and this should be appropriately taken into account in the cost calculation.

1. FORMING

The term “cold working” is refer to the forming process which is carried out at room temperature or at well below the recrystallization temperature.

1.1 Cold working

Austenitic stainless steels and nickel-base alloys may be readily cold-worked, provided that the specific material properties are taken into consideration.

• initial value of 0.2 % proof stress
• work hardening
• decrease in elongation

Maximum permitted deformation in cold working without heat treatment

Cold working alters the mechanical properties of the materials.

• All the materials in question are prone to appreciable work hardening accompanied by a decrease in the elongation after fracture in tensile testing.
• Some materials, especially those containing Mo, are prone to precipitation if, following extensive cold working, welding is carried out in the zone of deformation. As a result, these zones may become sensitised, i.e. their corrosion resistance may be impaired.

Normally for nickel alloys, cold working up to 15 % deformation is permitted without subsequent heat treatment. In individual cases, though, depending on the material and the duty heat treatment may be necessary even if the degree of deformation is £ 15 %, e.g. when using solution heat treated high-temperature alloys. In other cases, a higher degree of deformation may be permitted without heat treatment, especially if no welding is to be carried out in the zone of deformation.

Tools and machinery

Forming of austenitic chrome-nickel steels and nickel-base alloys is very often carried out with the same tools, fixtures and machines that are used for forming of mild steels. Extraneous ferrite particles on the surface of these tools lead in service to corrosive attack which may destroy the component’s passive layer and thus locally decrease the corrosion resistance. Care should therefore be taken that tools, supports and the like are cleaned to such an extent that no abraded particles of mild steel are carried onto the high-alloyed work pieces.

The product-side surfaces of the finished components should be checked for absence of ferrite, or pickled and passivated, before delivery / entry into service.

1.2 Hot working

Hot working is carried out in a range between the recrystallization temperature and the solidus temperature. As a result, the resistance to deformation is greatly reduced and the forces required to work the material are correspondingly lower.

The following table shows, by way of example, the hot working and heat treatment temperatures for a number of materials and nickel-base alloys.

During hot working, care should be taken that deformation proceeds as uniformly as possible so as to prevent the formation of an inhomogeneous grain structure. In addition, for low degrees of deformation (£ 30 % approx.), the forming temperature should be as close as possible to the lower limit in order to prevent coarse-grain growth. For higher degrees of deformation (> 30 % approx.), the higher temperatures are recommended.

After every hot working operation, heat treatment should be carried out in accordance with the mill product manufacturer’s instructions. Details with regard to heat control are described in the section Heat treatment.

2. HEAT TREATMENT

After hot working, the component should undergo heat treatment. After cold working, heat treatment may be unnecessary. The question of whether a finished component should be heat-treated should be settled with the client in each specific case, unless laid down in codes and specifications.

Heating

Work pieces must be clean and free from all kinds of contaminants before and during any heat treatment. Nickel alloys may become impaired if heated in the presence of contaminants such as sulphur, phosphorus, lead and other low-melting-point metals. Sources of such contaminants include marking and temperature-indicating paints and crayons, lubricating grease and fluids and fuels. Fuels must be as low in sulphur as possible. Natural gas should contain less than 0.1 wt.-% sulphur. Fuel oils with a sulphur content not exceeding 0.5 wt.-% are suitable. Due to their close control of temperature and freedom from contamination, thermal treatments in electric furnaces under vacuum or an inert gas atmosphere are to be preferred.

Treatments in an air atmosphere and alternatively in gas-fired furnaces are acceptable though, if contaminants are at low levels so that a neutral or slightly oxidizing furnace atmosphere is attained. A furnace atmosphere fluctuating between oxidizing and reducing must be avoided as well as direct flame impingement on the metal.

Work pieces made from materials with a high alloying content of molybdenum should be heated up rapidly. For heating, they should therefore be placed in a furnace which has already been heated to the desired temperature. Such materials include the 6% Mo steels and alloys 625, C-4, C-276 and 59

When the desired temperature has been reached, the following holding time is recommended as a guide:

For work piece thicknesses up to s = 10 mm              3 min/mm

For work piece thicknesses up to  s = 10 – 20 mm:       30 min plus 2 min/mm for

thicknesses > 10 mm

For work piece thicknesses          s = >20 mm:           50 min plus 1 min/min for

thicknesses > 20 mm

Cooling of high-molybdenum austenitic stainless steels and nickel-base alloys should be carried out rapidly so as to prevent undesirable precipitation. Delayed cooling, e.g. in the furnace, should be avoided at all costs, as this lead to the formation of precipitates, chiefly in the regions close to the grain boundary. Such precipitates may adversely affect both the corrosion resistance and the toughness properties of the material.

Proven results are obtained with a cooling rate of ³ 150 °C/min from the material-specific solution heat treatment temperature down to approx. 500 °C.

Heat treatment temperatures for a number of materials and nickel-base alloys

3. ABRASIVE BLASTING / PICKLING

In the case of components for wet-chemical service made from stainless steels and nickel-base alloys, it is usually necessary to remove the oxides formed during heat treatment.

For components intended for high-temperature service, the need for abrasive blasting/pickling should be agreed with the client.

As the oxides adhere very strongly in the case of the higher-nickel materials, it is advisable to blast-clean the components with a suitable grit or with glass beads or to grind them with, for instance, 80 grit mop wheels prior to pickling.

Pickling is best carried out with commercial pickling pastes or by immersion in a pickling bath consisting of approx. 15-22 % nitric acid and approx. 2-3 % hydrofluoric acid.

Immersion times at room temperature (examples):

– Cr-Ni steels                                 2 –   8 hours

– Ni-Cr-Mo-Fe alloys                              8 – 24 hours

– Ni and Ni-Cu alloys          10 – 15 minutes

– Ni-Mo alloys                                8 – 10 minutes

If the technical requirements, e.g. fume extraction, are met, it is recommended to increase the temperature of the bath to approx. 40 °C. This shortens the pickling time considerably.

The immersion time depends on the material, the oxide thickness and the temperature and should be tested at the start of the work.

In particular, the high-temperature materials with a fairly high C content as well as NiMo and NiCu alloys with a low Cr content are sensitive to over-pickling.

Any oxide still adhering after pickling should be removed with a chrome-nickel wire brush. The pickling operation should be repeated if necessary.

4. MACHINING

A high work-hardening rate and toughness and poor thermal conductivity are the main criteria applying to these materials. In machining, they should be taken into account by means of the following measures:

• Only use well-ground, sharp tools with smooth surfaces;
• Ensure maximum stability of tool, work clamping and machine tool in order to produce a clean cut;
• Apply plenty of coolant and lubricant;
• The tool should be constantly engaged, and with the relatively low cutting speed, a higher rather than too low a rate of feed should be used in order to prevent work-hardening of the material;
• If vibrations occur, the cause should immediately be established and remedied, because vibrations always lead to destruction of the cutting edge.

These working instructions have been compiled to the best of our knowledge, but no liability can be accepted for any errors.

5. WELDING

When welding high grade stainless steels & nickel-base alloys, the following instructions should be adhered to:

Workplace

The workplace should be in a separate location, well away from the areas where carbon steel fabrication takes place. Maximum cleanliness and avoidance of draughts are paramount.

Auxiliaries, clothing

Clean fine leather gloves and clean working clothes should be used.

Tools and machinery

Tools used for nickel-base alloys and stainless steels must not be used for other materials. Brushes should be made of stainless material. Fabricating and working machinery such as shears, presses or rollers should be fitted with means (felt, cardboard, plastic sheet) of avoiding contamination of the metal with ferrous particles, which can be pressed into the surface and thus lead to corrosion.

Cleaning

Cleaning of the base metal in the weld area (both sides) and of the filler metal (e. g. welding rod) should be carried out with acetone.

Trichlorethylene (TRI), perchlorethylene (PER), and carbon tetrachloride (TETRA) must not be used.

Edge preparation

This should preferably be done by mechanical means, i. e. turning, milling or planing; plasma cutting is also possible. However, in the latter case the cut edge (the face to be welded) must be finished off cleanly. Careful grinding without overheating is permissible.

Welding process

Different alloy applies different welding processes.