What Is a Fastener Material?
There is much consideration when choosing the ideal type and material for fasteners. For example, the material chosen should generally be reliable, cost-effective, and maintain durability in the environment.
This often means the corrosion resistance of the fastener material. The corrosion resistance of a particular fastener will also depend on the materials involved because the uneven metal that is in contact with each other may cause galvanic corrosion.
The most common materials for mechanical fasteners, such as bolts and screws, are steel.
Different grade of steel is available, depending on the strength required. If rust or rust is a concern, stainless steel, brass, or titanium may be used. Surface coatings, such as bright zinc plating, are also often used to prevent corrosion.
Not all fasteners are made equally, and the project you have on hand will determine not only the size, type, and length of the ideal fastener but also the material your fastener should be made from that best for your results.
Stainless Steel of Fastener Material:
Stainless steel is mainly used for long-lasting applications due to its corrosion-resistant nature and durability.
Scratching or bouncing the metal will not cause corrosion to the surface as corrosion resistance is present within the metal itself.
Stainless is a soft metal due to its low carbon content, so most stainless steel bolts are cold-formed and are not heat-treated or hardened.
Stainless bolts tend to be slightly magnetic due to cold formation and threading; some fastener will be more magnetic than others depending on size & how fast the cold forming process is.
Stainless fasteners usually have a clean silver color, which makes them common in finishing and decorative applications as well.
Stainless steels should never be used with aluminum, with galvanic corrosion likely to occur. Stainless steel will not rust due to scratches, making a thin layer of chromium an invisible protective layer.
This thin layer will reconstruct itself in the presence of oxygen. Note: If you are not in an oxygen-rich environment, it will not take long to rebuild or rebuild the material.
This will leave it open for possible corrosion. Stainless steel can be divided into three different types: austenitic, martensitic, and ferritic.
#1. Austenitic Stainless Steel
Austenitic stainless has the highest degrees of corrosion resistance of the three types. This type of stainless includes these grade: 302, 303, 304, 304l, 316, 32, 347, & 348. They also have a tensile strength between 80,000 – 150,000 psi. (between 15% -20% chromium, between 5% -19% nickels)
#2. Martensitic Stainless Steel
Martensitic stainless steel is considered magnetic steel. It can be heat-treated to increase its hardness & is not recommended for welding. These types of stainless include 410, 416, 420, and 431. They have a tensile strength between 180,000 and 250,000 psi. (between 12% -18% chromium)
#3. Ferritic Stainless Steel
The tensile strengths of ferritic stainless steels are 65,000 – 87,000 psi. Although it is still resistant to corrosion, it is not recommended for areas where corrosion is likely. This material cannot be heat treated. Due to the forming process, it is magnetic & not suitable for welding. The ferritic grades of stainless include 430 and 430f. (between 15% -18% chromium)
This is the most common stainless designation for hardware. For information on the properties of 18-8 stainless steel materials, see our Material Grade Identification and Properties Chart. 18-8 refers to any stainless steel consisting of approximately 18% chromium and 8% nickel.
More expensive than 18-8. Highly corrosion-resistant grade of stainless steel. Ideal in saltwater & chlorine environments.
The Stainless alloy is harder than 18-8 stainless steel but not resistant to corrosion.
The Steel of Fastener Material:
Steel is the most common fastener material. Plain steel fasteners with various surface treatments such as zinc plating, galvanization, and chrome plating are also available.
Steel fasteners are typically available in 4 grades: grade 2, grade 5, grade 8, and alloy steel. Several other grades exist but are often underutilized.
Grades 2, 5, and 8 are usually plated with a slight blue-ish or yellow zinc coating or galvanized to resist corrosion.
#1. Determining Bolt Grade
Note that in addition to grade marking, many bolts also have a manufacturer’s mark. The bolts are usually marked on the head depending on what grade of bolt they show.
See our Material Grade Identification and Properties Chart for a list of the most common grade marks.
- Grade 2:- Grade 2 is standard hardware-grade steel. It is the most commons grade of steel fastener and the least expensive. The grade 2 bolt has no head marking, except for a possible manufacturer’s mark.
- Grade 5 / Grade F:- Grade F is approximately equivalent to Grade 5. Grade F nuts are used with grade 5 bolts. Grade 5 bolts are hardened to increase strength and are the most common bolts found in automotive applications. Grade 5 bolts have three evenly radial lines on the head.
- Grade 8 / Grade G:- Grade G is approximately equivalent to Grade 8. Grade G nuts with grade 8 grade are used. Grade 8 bolts are more rigid than grade 5 bolts. They are thus robust and are used in demanding applications such as automotive suspensions. Grade 8 bolts have six radial lines evenly over the head.
#2. Alloy Steel
Alloy steel is the most common material manufactured in fasteners. Alloy steel fastener is often treated, coated, or plated with zinc for corrosion resistance.
Alloy steel is used for the hot-dipped galvanized process, which is treated in a molten zinc bath that creates a tightly bonded alloy finish.
Alloy steels are most often available in grade A, grade C, grade 2, grade 5, & grade 8. Untreated alloy steel fasteners are black.
#3. Silicon Bronze
Silicon bronze often referred to as bronze, is an alloy made of mostly copper and tin with small amounts of silicon.
Bronze is mainly used in marine environments. Bronze is similar to coppers in color and is sometimes seen in fine woodwork, where it is used for its appearance.
The main drawbacks of bronzes are their high cost. They were preferred over stainless in wooden boat constructions & re-fastening due to their superior corrosion resistance and over brass due to their high strength.
Brass is primarily an alloy of coppers & zinc. Brass is highly corrosion resistant & electrically conductive.
However, its use as fasteners is somewhat limited due to its relative softness. It is mainly used for its appearance.
Coatings of Fastener Material:
#1. Zinc Plating
Many steel fasteners are electrically coated with zinc for superior corrosion resistance. A fastener that has been zincing plated has a shiny, silver, or golden appearance, respectively known as clear or yellow zinc.
They are quite corrosive resistant but will rust if the coating is destroyed or exposed to marine environments.
#2. Hot Dip Galvanizing
Hot dipped galvanized fasteners are often used outdoors, especially in coastal environments. Galvanizing is another coating that uses a layer of zinc.
Hot-dip galvanizing puts the thickest coating possible on the metal, resulting in better corrosion resistance.
The hot-dipped galvanized bolt is not compatible with other nuts due to the thickness of the coating.
The galvanized nuts are slightly enlarged compared to other nuts to accommodate this coating.
The fasteners are chrome-plated and polished for appearance. Chrome plating offers corrosion resistance similar to zinc plating.
The main drawback of polished chrome is its high cost. If more corrosion resistance is required, the stainless steel can be chrome-plated, allowing the chrome to penetrate to prevent any corrosion.
Frequently Asked Questions (FAQ)
Fasteners are made from a variety of aluminum alloys, with elements such as manganese, silicon, iron, magnesium, zinc, copper, and silicon being added to increase strength and melting point.
What Is a Fastener?
A fastener is a hardware device used to join or hold materials together, typically as a non-permanent joint. Yes, the joint can be temporary or permanent; The connected components can be easily disassembled without damaging the joint in the former, and the joint becomes damaged or reduces strength in the latter case.
Best Fastener Materials for Corrosion Resistance
When it comes to fasteners, corrosion resistance is a crucial factor, especially in environments where moisture, chemicals, or other corrosive elements are present. Several materials are known for their corrosion resistance properties, and the best choice depends on the specific application and environmental conditions. Here are some materials commonly used for fasteners due to their corrosion resistance:
- Stainless Steel: Stainless steel is a popular choice for corrosion-resistant fasteners due to its high resistance to rust and staining. It contains a minimum of 10.5% chromium, which forms a passive layer on the surface, protecting the underlying material from corrosion. Stainless steel fasteners are available in various grades, such as 304, 316, and 316L, each with different levels of corrosion resistance.
- Titanium: Titanium is highly resistant to corrosion in various environments, including seawater and chloride-containing solutions. It forms a protective oxide layer that prevents further corrosion. Titanium fasteners are commonly used in industries such as aerospace, marine, and chemical processing where excellent corrosion resistance is required.
- Brass: Brass is an alloy of copper and zinc, and it offers good corrosion resistance, particularly in freshwater environments. It is often used in applications where both corrosion resistance and aesthetics are important, such as in decorative fasteners or musical instruments.
- Aluminum: Aluminum is lightweight and has good corrosion resistance due to the formation of a protective oxide layer. It is commonly used in fasteners for applications that require both corrosion resistance and low weight, such as in the automotive and aerospace industries.
- Inconel: Inconel is a nickel-chromium-based alloy that provides excellent corrosion resistance in extreme environments, including high-temperature and high-pressure conditions. It is often used in fasteners for applications involving chemical processing, marine environments, and aerospace industry.
Types of Fastener Materials and Their Properties
Fasteners are available in a wide range of materials, each with its own set of properties and characteristics. Here are some common types of fastener materials and their properties:
- Steel: Steel is one of the most widely used materials for fasteners due to its strength, durability, and availability. It comes in various grades, such as carbon steel, alloy steel, and stainless steel. Carbon steel fasteners are strong and affordable but may be susceptible to corrosion. Alloy steel fasteners have added elements to enhance strength and wear resistance. Stainless steel fasteners are corrosion-resistant and suitable for applications where rust prevention is essential.
- Stainless Steel: Stainless steel fasteners are highly corrosion-resistant due to the presence of chromium, which forms a passive oxide layer on the surface, protecting the material from rust and corrosion. Stainless steel fasteners are available in different grades, with the most common being 18-8 (containing 18% chromium and 8% nickel) and 316 (containing 16-18% chromium, 10-14% nickel, and 2-3% molybdenum), offering varying levels of corrosion resistance.
- Brass: Brass is an alloy primarily composed of copper and zinc. It is valued for its excellent machinability, corrosion resistance, and attractive appearance. Brass fasteners are commonly used in applications where both functionality and aesthetics are important, such as in decorative and architectural applications.
- Aluminum: Aluminum fasteners are lightweight and have good corrosion resistance due to the formation of a protective oxide layer on the surface. They are commonly used in applications where weight reduction is critical, such as in aerospace, automotive, and electronics industries.
- Titanium: Titanium is a lightweight and high-strength material known for its exceptional corrosion resistance, even in challenging environments. Titanium fasteners are commonly used in industries such as aerospace, marine, and chemical processing, where corrosion resistance and strength are crucial.
High-Strength Fastener Materials for Heavy-Duty Applications
Heavy-duty applications often require high-strength fasteners to withstand heavy loads, vibrations, and harsh conditions. Here are some high-strength fastener materials commonly used for such applications:
- Alloy Steel: Alloy steel fasteners offer high strength and toughness. They are made from steel with additional alloying elements such as chromium, molybdenum, and vanadium to enhance strength, hardness, and resistance to wear and fatigue. Common alloy steel grades used for high-strength fasteners include ASTM A193 Grade B7 and ASTM A325.
- Stainless Steel: Stainless steel fasteners can also provide high strength in addition to their corrosion resistance properties. Grades such as ASTM A193 Grade B8 (304 stainless steel) and ASTM A193 Grade B8M (316 stainless steel) are commonly used for heavy-duty applications where both strength and corrosion resistance are required.
- Titanium: Titanium fasteners combine high strength with a low weight ratio, making them ideal for heavy-duty applications where weight reduction is important. Titanium alloys such as Grade 5 (Ti-6Al-4V) and Grade 2 (commercially pure titanium) offer excellent strength, corrosion resistance, and durability.
- Inconel: Inconel is a family of nickel-chromium-based alloys known for their exceptional strength and resistance to high temperatures, corrosion, and oxidation. Inconel fasteners, such as Inconel 718 and Inconel 625, are commonly used in heavy-duty applications, including aerospace, gas turbines, and chemical processing industries.
- Monel: Monel is a nickel-copper alloy that offers high strength and excellent corrosion resistance. Monel fasteners, such as Monel 400 and Monel K500, are commonly used in marine, oil and gas, and chemical processing applications where strength and resistance to corrosive environments are essential.
Top-Rated Manufacturers of Fastener Materials in the USA
- National Bolt & Nut Corporation.
- Apex Stainless Fasteners.
- KD FASTENERS, INC.
- USA Fastener Group Inc.
- Dale Fastener Supply.
- American Bolt & Screw Manufacturing.
- Baden Steelbar & Bolt Corp.
- US Bolt Manufacturing Inc.
Benefits of Using Specialized Fastener Materials in Specific Industries
Using specialized fastener materials in specific industries can offer several benefits. Here are some examples of how specialized fastener materials can be advantageous in specific industries:
- Aerospace Industry:
- Lightweight Materials: Specialized materials like titanium and aluminum offer high strength-to-weight ratios, allowing for weight reduction in aerospace applications. This leads to improved fuel efficiency and increased payload capacity.
- Corrosion Resistance: Aerospace environments often involve exposure to moisture and extreme temperatures. Corrosion-resistant materials like stainless steel, Inconel, and titanium are ideal for ensuring long-lasting performance and safety.
- Automotive Industry:
- High Strength: Automotive applications often require fasteners with high tensile strength to withstand vibrations, dynamic loads, and harsh conditions. Alloy steel and high-strength carbon steel fasteners provide the necessary strength and durability.
- Corrosion Resistance: Automotive fasteners may be exposed to road salts, chemicals, and moisture, making corrosion resistance crucial. Stainless steel and coated fasteners can help prevent rust and maintain the structural integrity of automotive components.
- Marine Industry:
- Corrosion Resistance: Marine environments are highly corrosive due to saltwater exposure. Specialized materials like stainless steel, Monel, and super duplex stainless steel offer excellent resistance to corrosion, making them suitable for marine applications.
- Saltwater Compatibility: Fasteners used in marine applications must also be compatible with saltwater to prevent galvanic corrosion. Nickel-based alloys, such as Monel, have excellent saltwater compatibility.
- Oil and Gas Industry:
- High Temperature and Pressure Resistance: The oil and gas industry often involves high-temperature and high-pressure environments. Materials like Inconel, super duplex stainless steel, and alloy steel can withstand these extreme conditions.
- Corrosion Resistance: Oil and gas operations involve exposure to corrosive substances, such as hydrogen sulfide and acidic gases. Specialized materials like Inconel, Monel, and super duplex stainless steel provide superior corrosion resistance in these environments.
- Chemical Processing Industry:
- Corrosion Resistance: Chemical processing environments can be highly corrosive due to exposure to chemicals, acids, and high temperatures. Materials like Inconel, Monel, and specialized alloys with excellent corrosion resistance can ensure the longevity and safety of fasteners in these applications.
- Chemical Compatibility: Fastener materials need to be compatible with the specific chemicals used in the process to avoid chemical reactions or degradation. Specialized alloys can be selected based on their resistance to particular chemicals.
Fasteners are available in a wide range of materials, each with its own set of properties and characteristics. Here are some common fastener materials:
- Steel: Steel is one of the most widely used fastener materials due to its strength, durability, and availability. Carbon steel is commonly used for general-purpose fasteners, while alloy steel offers enhanced strength and wear resistance.
- Stainless Steel: Stainless steel fasteners are known for their corrosion resistance properties. They are commonly used in applications where rust prevention is essential. Various grades of stainless steel are available, such as 304, 316, and 18-8, each offering different levels of corrosion resistance.
- Brass: Brass is an alloy primarily composed of copper and zinc. It offers good corrosion resistance and is often used in applications where both functionality and aesthetics are important.
- Aluminum: Aluminum fasteners are lightweight and have good corrosion resistance due to the formation of a protective oxide layer. They are commonly used in applications where weight reduction is critical, such as in aerospace and automotive industries.
- Titanium: Titanium fasteners combine high strength with a low weight ratio. They offer excellent corrosion resistance and are commonly used in industries such as aerospace, marine, and chemical processing.
Dip Chromium Marine
It seems like you’re referring to the process of chromium plating, commonly known as chrome plating, in the context of marine applications. Chrome plating is a surface treatment method used to enhance the corrosion resistance and aesthetics of metal parts, including fasteners, by depositing a layer of chromium onto their surfaces. However, it’s important to note that traditional chrome plating may not be suitable for marine environments due to concerns about environmental impact and regulations.
Corrosion Resistant Fastener Coatings
Corrosion-resistant coatings for fasteners can provide an additional layer of protection against corrosion, extending the lifespan and performance of the fasteners in various environments. Here are some commonly used corrosion-resistant coatings for fasteners:
- Zinc Coatings: Zinc coatings, such as zinc plating or galvanizing, are widely used to protect fasteners from corrosion. The zinc layer acts as a sacrificial barrier, corroding preferentially to the base metal and providing corrosion resistance. Zinc coatings are commonly used in industries like construction, automotive, and general applications.
- Hot-Dip Galvanizing: Hot-dip galvanizing involves immersing fasteners in a molten zinc bath, forming a thick, durable zinc coating. This coating provides excellent corrosion protection and is commonly used in heavy-duty applications, including marine and outdoor environments.
- Electroplating: Electroplating involves depositing a thin layer of metal onto the surface of fasteners using an electric current. Various metals can be used for electroplating, including nickel, chromium, and cadmium, depending on the specific corrosion resistance requirements.
- Mechanical Plating: Mechanical plating is a process where a thin layer of metal, typically zinc or tin, is mechanically deposited onto the fastener surface. This coating provides good corrosion resistance and is commonly used for fasteners that require resistance against hydrogen embrittlement.
- Organic Coatings: Organic coatings, such as paints, epoxy coatings, or powder coatings, provide a protective layer over the fasteners. These coatings offer both corrosion resistance and aesthetics, making them suitable for various industries, including automotive, construction, and consumer goods.
Bright Zinc Plated Vs Stainless Steel
While zinc alloys are cheaper than stainless steel, they are also susceptible to more rust when exposed to moisture. Stainless steel can rust from excessive, prolonged exposure to water, but because it has much more resistance, this makes it a better alternative for most applications that may face exposure to water.
Fastener Coatings Corrosion Resistance
Fastener coatings play a crucial role in providing corrosion resistance and protecting fasteners from degradation in various environments. Here are some common fastener coatings known for their corrosion resistance:
- Zinc Coatings: Zinc coatings, such as zinc electroplating or hot-dip galvanizing, are widely used for corrosion protection. The zinc layer acts as a sacrificial barrier, corroding preferentially to the base metal and providing excellent corrosion resistance. Zinc coatings are effective in many applications, including construction, automotive, and general industrial uses.
- Dacromet: Dacromet is a non-electrolytic coating that consists of inorganic and organic compounds. It offers excellent corrosion resistance, high temperature resistance, and protection against chemical exposure. Dacromet coatings are commonly used in automotive, heavy machinery, and other demanding environments.
- Geomet: Geomet coatings are thin, metallic coatings primarily composed of zinc and aluminum flakes in an inorganic binder. They provide excellent corrosion resistance, high-temperature resistance, and protection against chemicals. Geomet coatings find applications in automotive, construction, and other industries where superior corrosion protection is required.
- Xylan: Xylan is a family of fluoropolymer coatings known for their exceptional corrosion resistance, low friction properties, and chemical resistance. They provide a tough, durable barrier against corrosion and are often used in industries such as oil and gas, chemical processing, and marine.
- Electroless Nickel: Electroless nickel coatings are formed by a chemical deposition process and offer excellent corrosion resistance, wear resistance, and uniform coverage. They provide protection against moisture, chemicals, and oxidation. Electroless nickel coatings find applications in various industries, including automotive, electronics, and aerospace.
Stainless Steel Fastener
Stainless steel fasteners are a popular choice due to their excellent corrosion resistance, strength, and versatility. They are widely used in various industries and applications where resistance to rust and corrosion is essential. Here are some key features and benefits of stainless steel fasteners:
- Corrosion Resistance: Stainless steel fasteners have a high resistance to corrosion, making them ideal for use in environments exposed to moisture, humidity, and corrosive substances. The presence of chromium in stainless steel forms a passive oxide layer on the surface, protecting the underlying material from corrosion.
- Strength and Durability: Stainless steel fasteners offer high tensile strength and durability, providing reliable and long-lasting performance. They can withstand heavy loads, vibrations, and harsh conditions without compromising their integrity.
- Aesthetic Appeal: Stainless steel fasteners have an attractive, polished appearance that adds to their appeal in various applications. They are commonly used in industries where aesthetics and visual appeal are important, such as architecture, interior design, and decorative applications.
- Wide Range of Grades: Stainless steel fasteners are available in various grades, each with different properties and levels of corrosion resistance. Common grades include 304 (18-8 stainless steel), 316 (marine-grade stainless steel), and 316L (low-carbon stainless steel). Choosing the appropriate grade depends on the specific application requirements and environmental conditions.
- Temperature Resistance: Stainless steel fasteners can withstand a wide range of temperatures, making them suitable for both high-temperature and low-temperature applications. Certain stainless steel grades, such as 310 and 330, offer enhanced heat resistance for applications involving extreme temperatures.
Nuts and Bolts Are Made of Which Material
Bolts and nuts are fabricated from a variety of materials. These options include metals and polymers. Stainless steel offers strength and corrosion resistance, while the polymer options have less strength than stainless, they are a good choice for resisting chemicals.
Bolt Material Properties
- Fatigue strength. The maximum stress a fastener can endure for a specific number of cycles before failing.
- Torsional strength. The torque load at which a fastener fails by becoming twisted off at its axis.
What Are Two Types of Sheet Metal Fasteners?
There are two basic types of sheet metal screws, self-tapping screws and self-drilling screws. Self-tapping screws have a sharp tip that is designed to cut through metal, but the metal must be pre-drilled before these screws can be used.
What Is the Meaning of Fastener?
A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components.