What is A4 Stainless Steel?

A4 grades of stainless steel are usually reserved for use in highly caustic environments where improved resistance to pitting corrosion is required, i.e Marine,  exhausts. Pitting corrosion occurs once the chromium becomes exhausted through self-passivation after caustic attack – the effects as usually local to the exposed areas. The pitting forms as the Iron atoms become exposed to Oxygen and form ‘rust’. The improved resistance comes from the addition of a higher proportion of Chromium, which helps to form a protective oxide layer on the iron – the more chromium you have the longer the protection it offers lasts.

Counting Tolerances: We make every effort to count fasteners accurately using our professional counting weighing scales.  As these scales are extremely sensitive, the slightest change in the working environment can have an effect on the instrument.  Please rest assured that we expect over 99% of our orders to be correctly counted and packed, but we would like to advise you that a 5% tolerance either greater than or less than what you have ordered may be shipped.  This will generally apply to the smaller ranges in our catalogue.