Hastelloy superalloys are prized by many industries due to their excellent corrosion resistance properties, ability to withstand high temperatures (melting point: 2300- 2470 °F/ 1260-1355 °C), ductility, and strength under stress.
The chemical, petrochemical, and oil and gas industries rely on Hastelloy as the obvious manufacturing material of choice for any application or component operating in highly corrosive and acidic environments.
However, there are many grades, or varieties, of Hastelloy. Each one has a different percentage of alloys, metals, and non-metal materials that give them varying degrees of tensile strength, oxidation resistance, and higher temperature tolerance.
All of these properties will influence your decision whether to use them.
To simplify the decision process, we’ll discuss the primary Hastelloy types, focusing on their unique compositions, properties, and applications within different industries.
Hastelloy B types are primarily composed of nickel and molybdenum, making them highly resistant to corrosive environments, particularly those containing hydrochloric acid.
There are two main Hastelloy B classes: Hastelloy B-2 and Hastelloy B-3.
An outline of each is given below.
Let’s look at the composition and properties of Hastelloy B-2 first.
| Composition | Properties |
| Nickel (68%) Molybdenum (28%) Iron (2%) Chromium (~1%) Cobalt (~1%) Manganese, Silicon, Carbon (optional, less than 1%) | Stress resistance Corrosion resistance Cracking & pitting resistance Resistance to reducing conditions (i.e., sulfuric, acetic, hydrogen chloride, and phosphoric acids) Hydrochloric acid resistance (all temperatures and concentrations) |
Due to the above properties, Hastelloy B-2 is commonly used in numerous applications within the chemical manufacturing industry.
It is particularly common in the production of herbicides, insecticides, acetic acid, ethylene glycol, ethylbenzene, and high-octane gasoline.
Next, here are the alloys and elements that comprise the B-3 class of Hastelloy, as well as the properties they provide.
| Composition | Properties |
| Nickel (65%) Molybdenum (30%) Some of the following: Cobalt (3%) Tungsten (3%) Manganese (3%) Chromium (1-3%) Iron (1-3%) Aluminum, Silicon, Titanium, Carbon (less than 1%) | High Thermal Stability Excellent corrosion resistance Stress corrosion resistance (chloride-bearing conditions) Cracking & pitting resistance Hydrochloric acid resistance (all temperatures and concentrations) Good ductility |
While Hastelloy B-3 has many of the same properties as Hastelloy B-2, its higher structural stability makes it easier to weld, fabricate, and service.
For that reason, it is often used for the construction of reaction vessels in the chemical processing industry.
While Hastelloy B types and Hastelloy C types are both able to resist oxidizing and reducing environments at high temperatures (1,400°F/760°C – 2,000°F/1,094°C), Hastelloy C has the added ability to carry heavy loads at temperatures of up to 1,600°F/871°C.
The primary grades of Hastelloy C include Hastelloy C-4, Hastelloy C-22, and Hastelloy C-276.
A description of each is given below.
Let’s start with the composition and properties of Hastelloy C-4.
| Composition | Properties |
| Nickel (55%) Chromium (14-18%) Molybdenum (14-17%) Iron (3%) Cobalt (2%) Manganese (1%) Titanium, Silicon, Phosphorus, Sulfur, Carbon (less than 1%) | High-temperature stability High-temperature resistance High-corrosion resistance High ductility |
As you can see, Hastelloy C-4 has many desirable properties for operating in harsh atmospheres.
Its outstanding stability and ductility under extreme heat and pressure, in particular, make Hastelloy C-4 suitable for manufacturing chemical processing equipment.
This includes boilers, centrifuges, agitators, dryers, evaporators, autoclaves, feeders, and generators.
Like Hastelloy C-4, Hastelloy C-22 is also made primarily of nickel but to a lesser degree.
Let’s take a look at its composition and properties.
| Composition | Properties |
| Nickel (~50%) Chromium (20-22.5%) Molybdenum (12.5-14.5%) Tungsten (2.5-3.5%) Cobalt (2.5%) Iron (2-6%) Manganese, Vanadium, Silicon, Phosphorus, Sulfur, Carbon (less than 1%) | Resistance to stress corrosion Resistance to crevice corrosion Resistance to pitting and cracking Resistance to reducing, oxidizing, and aqueous media Resistance to chemical process environments (acetic anhydride, ferric acids, seawater and brine solutions) Outstanding weldability |
The high chromium content plus the blending of tungsten and molybdenum in Hastelloy C-22 gives it a good degree of resistance to both oxidizing and reducing media.
Its multifaceted characteristics have made it a popular material for tubings and fittings in the pharmaceutical industry, as well as cell phone manufacturing parts.
It also plays a part in the production of pesticides and components found in various equipment in the chemical processing industry, such as flue grass scrubbers, sulfur dioxide scrubbers, and paper bleach plants.
Hastelloy C-276 was one of the first alloys to eliminate concerns over weldability issues because of its low carbon and silicon content.
This type also boasts a higher nickel content than any other Hastelloy C grade.
Here is a breakdown of its composition and properties.
| Composition | Properties |
| Nickel (57%) Chromium (16%) Molybdenum (16%) Iron (5%) Tungsten (4%) Cobalt (2.5%) Manganese (1%) Vanadium, Silicon, Carbon, Copper (less than 1%) | Excellent corrosion resistance (reducing environments) Resistance to oxidizing salts Resistance to stress corrosion cracking Resistance to pitting High resistance to multiple corrosion-producing agents (wet chlorine gas, chlorine dioxide, hypochlorite) |
The percentages of nickel, molybdenum, chromium, and tungsten in Hastelloy C-276 give it a variety of corrosion resistance properties, allowing it to withstand a wide range of harsh industrial environments.
In particular, high nickel and molybdenum levels make it extremely resistant to crevice and pitting corrosion, especially the kinds found in reducing environments.
Since Hastelloy C-276 can withstand the corrosive effects of a variety of harsh agents, it is commonly used within the pollution control and chemical processing industries, including the production of pollution control stack liners, heat exchangers, and reaction vessels.
Since it can handle the corrosive effects of corrosive gases like sulfur dioxide, it is also used for flue gas desulfurization system components that come into contact with these gases regularly.
The major difference between the Hastelloy C series and the Hastelloy G series is that the latter has a higher resistance to phosphoric and sulfuric acids.
There are many types of Hastelloy G, but the most widely used for manufacturing purposes are Hastelloy G-3, Hastelloy G-30, and Hastelloy G-35.
A description of each is given below.
Hastelloy G-3 is known for its corrosion resistance and resistance to reducing chemicals (reducing agents), which is largely due to its nickel and copper content.
Here is an overview of its basic chemical composition and properties.
| Composition | Properties |
| Nickel (roughly 36%) Chromium (21-23.5%) Iron (18-21%) Molybdenum (6-8%) Cobalt (5%) Copper (1.5-2.5%) Tungsten (1.5%) Silicon (1%) Phosphorus, Sulfur, Carbon, Columbium, Tantalum (less than 1%) | Excellent corrosion resistance (oxidizing chemicals & atmospheres) Resistance to Heat Affected Zone (HAZ) corrosion Good resistance to reducing chemicals Stress corrosion cracking resistance (chloride-containing environments) Pitting resistance Crevice corrosion resistance Intergranular corrosion resistance Good weldability |
Its nickel-chromium-iron composition gives it many properties that are useful for the production of handling equipment that can withstand sulfuric and phosphoric reducing acids.
Since Hastelloy G-3 has such good corrosion resistance when it comes to reducing agents, it is used for components that assist in the production of sour oil and gas, as well as for creating equipment within the chemical processing industry that handles and processes reducing acids.
Hastelloy G-30 is considered to be an improved version of Hastelloy G-3 because of its higher chromium content and added tungsten and cobalt.
As a result, it performs better in environments containing highly oxidizing acids like sulfuric, nitric-hydrochloric, and nitric-hydrofluoric acids.
It also has stronger chloride-induced cracking resistance than stainless steel. It is also highly resistant to the corrosive power of phosphoric acid (P205), which is one of the most important agricultural agrichemicals found in fertilizers.
| Composition | Properties |
| Nickel (43%) Chromium (30%) Iron (15%) Molybdenum (5.5%) Cobalt (5%) Tungsten (2.5%) Copper (2%) Manganese (1.5%) Niobium, Silicon, Carbon (less than 1%) | Resistant to oxidizing acids Resistant to P205 corrosion Cracking resistance |
Hastelloy G-30 is very useful in creating farming equipment that can withstand P2O5, as well as for the production of gas scrubbers that remove and eliminate gas pollutants.
Like Hastelloy G-30, Hastelloy G-35 was also designed to handle the “wet process” phosphoric acid (P2O5).
However, it has the added benefit of being extremely resistant to other oxidizing and reducing acids due to its extremely high chromium and moderate molybdenum content.
Hastelloy G-35 has the following composition and properties:
| Composition | Properties |
| Nickel (58%) Chromium (33%) Molybdenum (8%) Iron (2%) Cobalt (1%) Tungsten, Manganese, Aluminum, Silicon, Copper, Carbon (less than 1%) | Superior corrosion resistance to P205 Resistance to highly oxidizing acids Ability to resist grain boundary precipitates (within heat-affected zones) Good weldability |
A unique formulation has given it the ability to withstand phosphoric and oxidizing acids better than most of the other nickel and iron-based alloys which are currently used for industrial applications.
It is a suitable material for manufacturing applications within the chemical process industry as well as other applications within the farming industry, especially dealing with P2O5.
Other applications and systems that utilize Hastelloy G-35 include evaporators, caustic neutralizing systems, and other systems that require corrosion resistance in high temperatures of up to 800-1200℉ / 427-649℃.
This nickel-chromium-molybdenum alloy has perhaps the best combinations of properties among all of the Hastelloy types: excellent resistance to oxidation, high-temperature strength, and fabricability.
The combination of Hastelloy X’s exceptional characteristics is a direct result of its chemical constitution.
| Composition | Properties |
| Nickel (47%) Chromium (22%) Iron (18%) Molybdenum (9%) Cobalt (1.5%) Manganese (1%) Silicon (1%) Tungsten, Niobium, Aluminum, Titanium, Carbon, Boron (less than 1%) | Excellent strength (up to 2200°F / 1204°C) Excellent oxidation resistance (up to 2200°F / 1204°C) Resistance to stress-corrosion cracking Excellent forming characteristics Excellent welding characteristics |
Hastelloy X is an ideal manufacturing material for many applications within the petrochemical, aeronautical, and furnace industries.
With a strong combination of excellent corrosion and oxidation resistance as well as exceptional tensile and stress strength, it is extremely useful for many applications that require excellent functional, as well as mechanical properties.
Hastelloy X is used in the manufacturing of gas turbine parts, industrial furnace applications, gas turbine combustion cans, heat-treating equipment, furnace rolls, and a variety of aircraft parts.
All Hastelloy types share common characteristics useful in a wide range of applications within the chemical processing, waste pollution control, oil and gas production, nuclear power, and utility industries.
The different grades of Hastelloy also share common compositions, particularly high nickel and molybdenum with low carbon content.
This helps them maintain their corrosive-resistance properties in high temperatures and acidic environments.
The above-mentioned grades of Hastelloy are by no means a complete list of the different grades and subgrades of Hastelloy available for manufacturing purposes.
However, the ones that were mentioned are some of the most commonly used for applications that require added corrosive and stress-resistant strength in various chemical, petrochemical, and nuclear environments.
To get a better idea of which type of Hastelloy is best suited for your specific industrial application, contact a custom metal parts manufacturer, as they will help guide you to the one that is the best fit for your project and budget.
For further information about our Hastelloy superalloys, contact us via the convenient website form or submit a request for quote directly.
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