Coach Bolts - Metric - A4 Stainless Steel

Often called carriage bolts or cup square hex bolts, coach bolts have a round head with a square underside.

With our stainless steel coach bolts you will need to please order the nuts separately.

Coach bolts are available in a range of sizes. All have metric coarse threads. They are most commonly used in the construction and timber trades.

Please note: All coach bolts up to 100mm length are fully threaded. For our coach bolts over 100mm, thread length can vary depending on the manufacturer, so some products may not be fully threaded. Please feel free to check with us before placing your order to confirm thread length.

Metric is the most common thread type in production today. Usually specified as M then a number x another number. This signifies the thread diameter and the length of the fastener.

For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. Length is usually measured from the underside of the fastener head.

A4 Stainless is often referred to as 316 or 18/10 stainless. As in A2 above, the numbers 18/10 refer to the chromium and nickel content- 18% chromium and 10% nickel. It is often used in marine or chemical environments as it has greater corrosion resistance than A2.

The chemical composition of both A2 and A4 stainless steel are almost identical with the most notable differences being the higher nickel content and the addition of Molybdenum in A4. Molybdenum is a silvery white metal that is highly corrosion resistant, very ductile and has an extremely high melting point.

There can also be Titanium present in A4 stainless at the option of the manufacturer.

Typically, A4 grade stainless steel costs slightly more than A2 because of its enhanced chemical and production properties. The extra cost can be justified, however, because hardware made of A4 stainless steel is extra resistant to tarnish and corrosion, enabling it to last a very long time.

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