Materials and Finishes Used in Fasteners and Fixings

Our Account Managers are on hand to support you in making the right choice for your intended application.

Our range of stocked fasteners and fixings includes over 20,000 products manufactured from stainless steel, mild steel, high tensile steel, brass, and other materials, in a variety of finishes.

We can source any other material and finish combination required. Find out more about our non-standards service here.

If you are uncertain as to what material or finish would be best, our Account Managers are always on hand to advise.

Popular Fastener and Fixing Materials

Material	Description	Popular Applications
Mild Steel Fasteners	Mild steel, also known as carbon steel, is a form of steel that contains a very low carbon content. This makes it more ductile and easier to machine and weld compared to high tensile steel.	• Construction • Joinery • Electrical • Automotive
High Tensile Steel Fasteners	One of the best and most popular materials used in the manufacture of fasteners. Available in various grades, high tensile steel contains additional alloys to increase its strength and durability.	• Automotive • Mechanical Engineering • Construction
A2 and A4 Stainless Steel Fasteners	Stainless steel is a popular choice for fasteners and fixings due to its high-level resistance to corrosion. A strong metal, it will withstand harsh corrosive environments and extreme weather. As stainless steel does not rust or tarnish, products last longer and remain visually better.	• Industrial Pipework • Breweries • Medical • Marine • Transport • Sewage Plants
Brass Fasteners	Brass is an alloy of zinc and copper, giving the yellow-gold finish, and is often used for its aesthetics. Brass is highly corrosive-resistant, making it ideal for external and marine environments. Brass is often used in electrical applications due to its low conductivity properties. Brass is also less vulnerable to petrol and other corrosive materials.	• Electrical • Automotive • Architectural • Furniture

A large amount of socket head cap screws with one large socket head cap screw placed on top, all with a bright zinc plate finish.

Other materials which we can supply include:

Nylon
Titanium
Monel
Tungsten
Aluminium

Popular Fastener and Fixing Finishes

Finish	Description	Popular Applications
Self-Colour Fasteners	Natural uncoated mild steel with a thin layer of oil applied. A popular choice for internal use where corrosion resistance is not required. Self-colour fasteners vary from silver to black in colour.	• Joinery / Timber • Construction • Furniture • Hardware
Bright Zinc Plated (BZP) Fasteners	The most common fastener finish, BZP is achieved by electrodepositing zinc onto the fastener or fixing. A zinc plating will provide excellent corrosion resistance but is not suitable for outdoor use.	• Automotive • Construction • Machinery
Zinc and Yellow Plated (ZYP) Fasteners	Applied in the same way as BZP but provides a higher level of corrosion resistance by adding two protective layers to the fastener. Firstly, a zinc coating, followed by a passivate which results in a yellow/gold finish. Zinc and yellow is commonly used in the automotive industry but is not suitable for outdoor use.	• Automotive • Furniture • Rail • Joinery
Hot Dipped Galvanised (HDG) Fasteners	By dipping fasteners into a bath of molten zinc, a weather-resistant layer is created to protect the steel from corrosion. Whilst cost-effective, a galvanised coating is quite thick, meaning that the finish increases the final size. As a result, HDG fasteners should be used with other HDG fasteners, e.g. nuts and bolts.	• Industrial Pipework • Sewage Plants • Construction
Geomet Fasteners	This metallic silver low thickness coating is similar to a galvanised finish but does not change the size of the fastener. Available in various types, providing a range of corrosion levels, Geomet is comprised of aluminium and zinc flakes in a binder fluid. Suitable for outdoor use, a Geomet coating provides excellent corrosion resistance, conducts electricity, and offers optimum friction performance.	• Electronics • Automotive • Rail
Black Oxide Fasteners	Adding a mild abrasion and corrosion protection, a black oxide finish is used when a reflective metal is not suitable. The result is a black finish that will not impair vision.	• Architectural • Automotive

A selection of Thunderbolt self-tapping anchors with a Zinc and Yellow finish.

Other finishes which we can supply include:

Chrome
Nickel
Sheradised
Powder Coated

A mix of stainless steel fasteners and fixings with a large A2 nut on the top.

Useful Technical Data for Stainless Steel

The International Organisation for Standardisation (ISO) published in May 1979 a specification (standard 3506) for stainless steel fasteners.

This defines a four-digit product designation:

The first digit indicates the general classification of steel: A= austenitic.

The second digit indicates the type of alloying elements: A2= austenitic 18/8 type (not free-machining types) A4= austenitic 18/10/3 type.

The third and fourth digits indicate the strength (mechanical property) class and represent one-tenth of the tensile strength expressed in Newtons per Millimetres squared (N/mm²): 50 = lowest strength class which is usually for products of softened steel and with a machined thread.

70 = higher strength class resulting from cold forging and thread rolling.

80 = highest strength attainable by multiple cold forging thread rolled parts, and especially when drawn cold bars are used.

Thus A2-70 = austenitic 18/8 class 70 forged with minimum N/mm² tensile strength of 2,700 N/mm².

Mechanical Properties of Austenitic Stainless Steel Fasteners

ISO 3506 Steel grades A1, A2, and A4.

			Bolts, Screws and Studs			Nuts
	Property Class	Diameter Range	Tensile Strength N/mm² (tonf/in²) min	Yield Stress N/mm² (tonf/in²) min	Ductility (total elongation)	Proof Load Stress N/mm² (tonf/in²) min
A1	50	Up to M39	500 (32.4)	500 (32.4)	0.6d	500 (32.4)
A2	70	Up to M30	700 (45.3)	700 (45.3)	0.4d	700 (45.3)
A4	80	Up to M20	800 (51.7)	800 (51.7)	0.3d	800 (51.7)

All property values are determined on finished products, not on machined test pieces.

All tensile stress values are calculated in terms of the nominal (mean) tensile stress area of the thread. Yield stress is defined as the stress to give 0.2% permanent strain.

Typical Chemical Compositions

Steel grade	Percentage Composition (max)
Steel grade	C	Si	Mn	P	S	Cr	Mo	Ni
A1	0.12	1.0	2.0	0.20	0.12 to 0.35	0.15 to 19.0	0.6	8.0 to 10.0
A2	0.08	1.0	2.0	0.05	0.03	0.15 to 19.0	0.6	8.0 to 13.0
A4	0.08	1.0	2.0	0.05	0.03	0.03	2.0 to 3.0	10.0 to 14.0

National steel specifications give narrower limits and other additions may be included for special requirements: e.g. copper to improve cold-forming properties: niobium and/or titanium to improve the corrosion resistance of welds.

The above information is for guidance only.

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