Selecting the Fastener Material

Selecting the Fastener Material Fasteners are available in a wide range of specifications however whether the user is planning to use a bolt, screw, clamp, peg, rivet or some kind of self-clinching hardware, choosing material ideal for the needed application is a vital concern. For instance, selecting a steel fastener instead of aluminium can bring effect on the quality and duration of the joint it forms. Various factors, for example – environmental circumstances, physical stress requirements, presence of corrosive elements, overall structural stability can affect the effectiveness of the material.

The majority of the available industrial fasteners are made up of aluminium, various grades of steel/stainless steel, certain synthetic non-metals, and brass. What's more, metals, for example, titanium are likewise significant for building metal fasteners, in spite of the fact that they have limited application in a limited range of fields. By and large, materials of the fastener are judged

or decided on their ability towards post fabrication treatments, mechanical properties, cost efficiency along with several other tributary criteria. For special needs, you can also get them custom made.

Steel Fasteners In fastener production, the most commonly used material is STEEL, so much in use that it constitutes almost 90% of the fasteners manufactured annually. The popularity of steel is because of its high degree of formability in addition to its other attributes which are durability and tensile strength. Compared to other metals available for fastener production, steel is considered inexpensive to fabricate. The metal is normally processed with chrome plating or zinc however the same can be done without any surface treatments.

Carbon Steel Bolt Grades Sub-categorizing steel fastener, the most frequently used in fastener production is the carbon steel, available in grades 2, 5 and 8. These are the typical carbon steel standard for screws and bolts. Talking about their mechanical strength, there is great range available, which is 50 kilo pounds per square inch (ksi) to 300 ksi. In a finished product, the material properties that are expected for these grades include – a) Grade 2 – Highly workable, Grade 2 is a low carbon category with least durability and least cost. b) Grade 5 – Made from unalloyed medium carbon group, Grade 5 steels are work hardened to tweak their strength. Grade 5 is most commonly used in automotive industry. c) Grade 8 – Typical medium carbon alloys, Grade 8 are work hardened to a very high degree, making them better suited and stronger for mechanically straining applications.

The very common use is seen in vehicle suspension systems. d) Alloy steel – As the name suggest, it is an alloy that has high-strength of carbon steel, which can be treated thermally up to 300 ksi. The types offer low corrosive properties, which are the benefits it achieves from additional coating. The type is very strong however it can be brittle and rigid.

Stainless Steel Fasteners Talking about stainless steel, it’s an alloy that amalgamates the attributes of low grade carbon with a definite percentage of nickel and chromium. The chromium component is the reason behind stainless steel’s resistance to corrosion, which does not fade with time (long term use) or deformation. Though, the lower carbon content prevents stainless steel from becoming effectively hardened, allowing it to be stronger than most grade 2 steels, but less strong or weaker than most grade 5 and 8 varieties. These stainless steel fasteners are less magnetic when

compared to their other steel counterparts. The two major varieties of stainless steel fastener material include – a)

Martensitic Stainless Steel – This group of stainless steel includes durable and strong stainless steel, which are further strengthened using heat treatments. They have lower corrosion resistance and are more magnetic than other types available.

b)

Austenitic Stainless Steel – Most of the fasteners available for use belong to austenitic family. The high levels of nickel and chromium in this family offer very high corrosion resistance and they have an extra-ordinary ability to withstand physical strain. They are the most preferred types even though they are available at higher cost than their counterparts.

Bronze and Brass Fasteners In the production of the fastener, an alloy bronze owing to its high corrosion resistance is used.

Bronze consists of tin and copper that makes it well-suited for aquatic applications, for instance – underwater constructions or ship building. The copper present in it gives it a reddish colour however when compared to other fastener material, bronze is considered expensive. Brass, which is an alloy of zinc and copper is quite similar to bronze in its electric conductivity and anticorrosive properties however it is a relatively soft metal with lower tensile strength. Owing to its yellowish golden colour, the metal finds special place as a preferred fabricating material.

Apart from the above mentioned metal fasteners, the industry also prefer synthetic plastic material, Nylon for specific fastener applications. The attributes that gives nylon this special place is its – high electrical and thermal insulating and corrosion resistance properties however under high temperatures, nylon is subject to severe deterioration and might become weak in low-temperatures. Also, in comparison to metal fasteners, nylon has low tensile strength making it less effective for requirements with high physical stress.