Grade 304 stainless steel

Stainless steel, also known as inox steel or inox from French “inoxydable”, is defined as a steel alloy with a minimum of 11% chromium content. Stainless steel does not stain, corrode, or rust as easily as ordinary steel, but it is not stain-proof.
Stainless steel’s are divided into grades (and sub-grades) which are determined by their specific constituent elements – e.g. Chromium and Nickel; these grades help identify whether that steel is more or less suitable for any given application and, for example in guidance on the materials corrosion resistance, mechanical or thermal performance or machinability.

Specifiers should be aware that in recent years, primarily due to the rise in price of key elements such as nickel, that many non-internationally recognised grades of stainless have appeared on the market with varying, and sometimes unknown performance characteristics. The main example of this appears to be the substitution of Manganese for more expensive Nickel which is generally understood to significantly reduce the corrosion resistance of the end product.

Grade 316 stainless steel
Grade 316 (also known as Marine grade) is an improved version of grade 304 stainless with the addition of Molybdenum and a slightly higher nickel content. The resultant composition of 316 gives the steel increased corrosion resistance and therefore makes it particularly suitable for aggressive coastal environments or where atmospheric pollution is present. The molybdenum makes the steel more resistant to pitting which generally pre-empts corrosion or rusting.

HI-LOAD hinges are made from grade 304 stainless steel sourced from European steel mills with full traceability.

Mild/Carbon steel

Steel is derived from iron is therefore a ferrous metal. The iron is alloyed with carbon to produce steel. Steels are described as low, medium- or high-carbon steels, according to the percentage of carbon they contain, grades typically described as mild mild steel being less than 0.3%.

Carbon steels are stiff and strong and are therefore widely used as a construction material. It has limited corrosion resistance however as it is reactive, the iron content will readily revert back to iron oxide (rust) in the presence of water, oxygen and ions. The readiness of steel to oxidize on exposure to damp environments (including cleaning) means that it must be adequately protected from the elements in order preserve it. Mild steel also exhibits ferro-magnetism (i.e. it is magnetic).