Fastener Materials: Fasteners are manufactured from a variety of materials like Carbon Steel, Stainless Steel, Aluminium, Copper, Nickel, Titanium, Bronze, Inconel, Monel, Brass, Plastics, other non-ferrous materials, and many others. Fasteners come in all sorts of materials and can be coated or finished to suit any particular application. A wide variety of fasteners is available for a number of uses, but the material you choose will affect quality and duration. For example, steel is often preferable over aluminium.
Fasteners, at their core, are machines that hold things together. They come in a variety of shapes and sizes and are made from a range of materials. But they are all used to solve the same problem: keeping different objects together. When you need fasteners, there are a huge variety of them available. You can choose what material and finish will best suit your application.
Fasteners Material Selection:
The Raw Material selection should be based on various factors such as
- Corrosive Environment
- Strength Required
- Magnetic Properties
- Electrical Conductivity
- Coatings/Finish Required
- Life Expected
In general majority of fasteners are made from steel because of its inherent strength properties, low cost and excellent workability as compared to other fasteners materials. Steel is the most common material preferred for making fasteners. Fasteners made out of steel are further plated to give more life to corrosion like Zinc Plating, Galvanization, HDG, Chrome Plated, Cadmium Plated, Xylan Coating, Phosphating, Geomet Coating, Dacromet Coating, Nickle Coating, PTFE coating etc.
The steel material is further comes in
- Low Carbon Steel
- Medium Carbon Steel
- Alloy Steel.
Low Carbon Steel:
Low Carbon steel contains less than 0.25 % of carbon and has outstanding ductility along with toughness. It can be easily welded and machined and is most economical to produce. This Low Carbon Steel Fasteners has a tensile strength in between 400 Mpa to 500 Mps. Low carbon Steel fasteners comes in (Metric class 4.6, 4.8 & 5.8) (Imperial Class Grade 2). Fasteners made of this low carbon steel grade are used in general applications where there are less stresses, less strength required and cost concern. Low Carbon steel fasteners with selective coatings like Zinc Plating, HDG (Hot Dip Galvanized) can be more corrosion resistance and can improve the life of fasteners.
Medium Carbon Steel:
Medium Carbon Steel contains carbon ranging from 0.25% to 0.60%. Medium Carbon steel can be easily heat treated and has good tensile strength in between 690 Mpa to 830 Mpa. Medium carbon Steel fasteners comes in (Metric class 8.8) (Imperial Class Grade 5). Fasteners made of Medium Carbon steel are used in applications where there is good strength required & medium stresses involved. This medium carbon steel fasteners are majorly used in automotive applications.
Alloy Steel contains manganese, chromium, boron, silicon etc. Adding this elements improve the capacity of the alloys to be heat treated and giving wide variety of strength to ductility combinations. Alloy steel has high tensile strength of 1034 Mpa. Alloy steel fasteners comes in (Metric class 10.9 & 12.9) (Imperial Class Grade 8). This Allot steel fasteners are generally used where high strength is required. Alloy steels are work hardened to a high degree, which makes them stronger and better suited for mechanically straining applications like vehicle suspensions, oil & gas industry, flanges and fittings etc. Alloy steel which has low corrosion resistance and typically benefits from additional coatings/plating. Fasteners made out of alloy steel are extremely strong when compared to Low and Medium grade carbon steel, but very brittle.
Stainless Steel offers more corrosion resistance properties due to presence of low chromium metals in it. The presence of this chromium makes the metal passive and it can rebuilt in presence of oxygen even through the layer is damaged. Due to its most corrosion resistance properties Stainless Steel fasteners are majorly used in applications where there require high resistance to corrosion.
At Intact360, we manufacture different Stainless Steel fasteners which include Nuts, Bolts, Studs, Screws, Washers, Anchor Bolts, Foundation Bolts, Rivets, Hose Clamps and Studs which gives more corrosion resistance and enhance life of fasteners.
One should know the benefits or advantages that are associated with Stainless Steel material when compared with other steel fasteners. There are several benefits of using stainless Steel material in fasteners which are listed below in detailed manner.
Benefits / Advantages of Stainless-Steel Fasteners:
- Resistance to Corrosion
- Better Visual Appearance
- Excellent Life Cycle
- High Value
- Temperature Resistant
- Largely Non Magnetic
- Low Maintenance
- Readily Available
Resistance to Corrosion:
Stainless Steel Fasteners are highly resistant to corrosion when compared to steel fasteners. Stainless Steel Material has 10% of chromium metal in its composition and this makes a thin layer of chromium oxide to be formed over the outer surface of the material. This layer formed due to presence of chromium composition effectively prevents any corrosion or degradation from happening upon oxidation or exposure to other corrosion causing chemical reactions.
Due to this resistance to corrosion makes them the number one choice for manufacturers. Stainless Steel material is resistant to both internal and external hydrogen embrittlement, making it the most sought material for manufacturing fasteners. Corrosion resistance refers to a metals ability to deal with damage caused by oxidization as well as other chemical reactions.
Better Visual Appearance:
Stainless Steel fasteners, do not rust or tarnish and due to this they give you a better look and last longer. Its rugged yet good look makes it a high choice for Manufacturers to let the fasteners show where they are being used. The look of the equipment fitted with this Stainless Steel fasteners obviously unmatchable in comparison to equipment build with other material grade fasteners. Due to its better looks, it is widely used in manufacturing Industries and Construction. Stainless Steel Fasteners like Nuts, Bolts, Studs, and Washers etc. are quite appealing in comparison to rest of their counterparts.
Excellent Life Cycle:
Since Stainless Steel fasteners offers excellent durability, they can be used in extreme temperatures and also in marine applications where there is huge chances of getting rusted. No other material can offer such long lasting benefits compared to Stainless Steel fasteners. It may seem little bit costlier, however in the long run you will definitely save more over time and can be said that Stainless Steel fasteners are more cost-effective in the long run. So anyone looking for long run value they should definitely go with Stainless Steel fasteners. Stainless Steel fasteners are frequently seen in under water equipment’s which require high corrosion resistance. Due to its longer life, Stainless Steel fasteners no need to get replaced very frequently.
Stainless Steel fasteners are strong and they will hold up in very harsh corrosive environments. Stainless Steel fasteners can also do well in very high and extreme low temperatures. Stainless Steel fasteners tend to last longer than many other alternatives that are cheaper.
Stainless Steel fasteners are considered to be high cost effective in long term. Initially it’s seems to be costlier in comparison to other steel fasteners, but it has a lasting value with minimal replacement rate. When compared to other grade fasteners, Stainless Steel fasteners have advantage of excellent life cycle and for this reason they are rarely replaced.
Stainless Steel fasteners are considered to be resistant to extreme weather conditions irrespective of hot weather conditions or cold weather conditions. For any manufacturer one of the most important advantage of using Stainless Steel fasteners is that they can withstand higher and very lower temperatures. For example if you are constructing a building in a temperature prone place, you can use these fasteners for improving its performance.
Stainless Steel alloys possess less magnetic properties compared to other alternative steel grades. One can choose the specific grade of stainless Steel fasteners based on their applications relatively to magnetic property. Austenitic stainless Steel grades like 304 & 316 have a high amount of austenite which makes them mostly non-magnetic. However, if the crystal structure of an austenitic Stainless Steel is changed through work-hardening or special thermal treatment, then ferrite can form in some locations making the steel partially magnetic.
Stainless Steel is more resistive to corrosion and very easy to clean. That’s the reason a very low maintenance cost is involved when compared to other fasteners grades. Stainless Steel fasteners don’t add up scratches, thanks to their longevity, that they allow you to spend less money on replacing your fasteners.
Stainless Steel fasteners are very easily available in market and this is one of the best parts of using them. Most of the fasteners distributors have readily stock of this Stainless Steel fasteners.
Stainless steel comes in Four grades.
- Austenitic Stainless Steel
- Martensitic Stainless Steel
- Ferritic Stainless Steel
- Duplex Stainless Steel
Austenitic Stainless Steel
Austenitic Stainless Steel grade contains chromium content in between 15% to 20% and nickel in between 5% to 19%. The presence of this metals in Austenitic Stainless Steel offers a higher degree of corrosion resistance than the other two types of Stainless Steels. The tensile strength of austenitic stainless steel varies in between 500 Mpa to 800 Mpa. Austenitic Stainless Steel grades includes AISI 302, 303, 304, 304L, 310, 316, 316L, 321, 332, 347 & 348.
Martensitic Stainless Steel
Martensitic Stainless Steel contains 12% to 18% chromium, and have poor welding properties and are considered magnetic. The tensile strength of Martensitic Stainless Steel varies between 500 Mpa & 1100 Mpa. Martensitic Stainless Steel are structurally similar to ferritic Stainless Steels, with the only difference in carbon percentages. Carbon percentage of Martensitic Stainless Steel is around 1%.
This type of Stainless Steel should only be used in mild corrosive environments and high strength needed. Martensitic stainless steels can be tempered and hardened much like carbon and low-alloys steels. This material used where a moderate types of corrosion resistance and high strength is needed. Generally companies use Martensitic Stainless Steel mostly in long products that require sheet and plate form. Martensitic Stainless Steel Include AISI grades 410, 416, 420 & 431.
Ferritic Stainless Steel:
The second most commonly used form of Stainless Steel after Austenitic alloys. Ferritic Stainless Steel contain 15% to 18% chromium and it is non-heat-treatable. Ferritic Stainless Steel have very poor weld characteristics and magnetic. As the name implies, Ferritic is magnetic. These alloys can be hardened through cold working. Ferritic Stainless Steel tend to be less expensive because of their reduced nickel content. The tensile strength of Ferritic Stainless Steel is in between 450 Mpa & 600 Mpa. The carbon composition in Ferritic Stainless Steel doesn’t exceed 0.10%. Industries often choose Ferritic Stainless Steel because of its resistance to stress corrosion cracking. Some Ferritic Stainless Steel grades include 430, 430F & 434.
Duplex Stainless Steel:
Duplex Stainless Steel are majorly combinations of both Austenitic and Ferritic Stainless Steel. These alloys are stronger than both Ferritic and Austenitic Stainless Steels. Duplex Stainless Steel possess less nickel composition and that’s the reason they are less expensive than Austenitic Stainless Steel. They combine many of the beneficial properties of Ferritic and Austenitic Stainless Steels. The Duplex microstructure contributes to the high mechanical strength and high resistance to stress corrosion cracking.
The high strength of Duplex Steel grades is also as a result of alloying with nitrogen and other characteristics include good abrasion, erosion resistance, good fatigue resistance, high-energy absorption and low thermal expansion. Furthermore Duplex Stainless Steel are weldable. Some common Duplex Steel alloys include 318L, LDX 2101, LDX 2304, 2507, 2205, UNS S32750, UNS S32205 and 4501.
Aluminium material is light in weight and has high strength to weight ratio. Aluminium has some excellent characterises excellent corrosion resistance in most environments, excellent electrical and thermal conductivity, can be easily cold formed or hot forged and easily machinable.
Aluminium fasteners are often made from alloys, including iron, zinc, copper and even manganese or silicon. Due to this features Aluminium is the most popular choice for fasteners amongst non-ferrous metals. The tensile strength of Aluminium is ranging between 90 Mpa for pure Aluminium up to 414 MPa. Aluminium fasteners are generally manufactured from AISI Grades 2024, 6061, 6262 & 7075.
Aluminium Fasteners Uses
- Aircraft Fittings
- Gears and Shafts
- Military Applications
- Computer Parts
Copper material are basically used in fasteners that require a high degree of electrical and thermal conductivity and corrosion resistance. Copper material is non-magnetic and cannot be hardened either than by cold working.
The tensile strength of pure copper is about 207Mpa. Copper is alloyed with silicon and manganese or aluminium for greater strength. Typical alloys of Copper are high-silicon bronze, low-silicon bronze, silicon-aluminium bronze and cupro-nickel. A copper- Nickel alloy used for high strength and resistance to saltwater corrosion.
Silicon Bronze materials are best known for their corrosion resistance and for this reason they can be used in gases, acids and salts without corroding. Silicon Bronze is a copper-silicon alloy that is often used in electrical power distribution applications. Silicon Bronze alloy 655 and alloy 651 materials are more corrosion resistant and stronger than brass. These material are made from 95% to 97% copper, 2% to 3% silicon and 1% manganese.
Silicon Bronze fasteners offer superior strength to other metals like stainless steel and brass. Silicon Bronze fasteners has beautiful appearance as well apart from their beneficial mechanical properties.
Advantages of Silicon Bronze fasteners
- Non-Magnetic Properties
- Corrosion Resistance
- High thermal conductivity
- Friction reduction
- Minimal clearance requirement
Applications of Silicon Bronze Fasteners
- Gas exposure
- Power & Energy
Nickel base alloys have excellent strength properties, exceptional toughness and ductility and perform well in both high and low temperature extremes. Nickel alloy base fasteners have a tensile strength of 550 Mpa, while those made from nickel-copper-aluminium alloys have a tensile strength of 896 Mpa.
Nickel alloy fasteners offer excellent performance and oxidation resistance at high temperatures. Nickel alloy fasteners are of high cost and that’s the reason used in rare applications. Nickel alloy fasteners comes in respective grades Nickel 200 UNS N02200 & Nickel 201 UNS N02201.
Inconel material is an austenitic nickel-chromium based alloy which is commonly used in extreme environments. Due to the thick protective passivating oxide layer that forms when heated, Inconel can withstand immense degrees of pressure and heat when compared to other fastener materials. Inconel also retains its strength over a broad temperature range, making it highly useful for automotive and aerospace applications. Inconel material can be easily formed and can be hardened and strengthened only by cold work.
Advantages / Benefits of Inconel Fasteners:
- Excellent corrosion resistance at elevated temperatures
- High strength material with excellent toughness
- High temperature stability up to 2200°F (982°C)
- Inconel can withstand extreme amounts of oxidation and carburization.
- Inconel provide excellent mechanical properties like good workability and high strength.
Applications of Inconel Fasteners
- Turbine engines
- Nuclear Reactors
- Oil Shafts
- Chemical Processing plants
- Oil & Gas Industry
- Cryogenic Tanks
Inconel Material Grades:
Inconel Fasteners grades are Inconel 600 (UNS N06600), Inconel 601 (UNS N06601), Inconel 625 (UNS N06625), Inconel 686 (UNS N06686), Inconel 718 (UNS N07718), Inconel 725 (UNS N07725), Inconel X750 (UNS N07750), Inconel 825 (UNS N08825).