Stainless Steel
is a term coined early in the development of these steels for cutlery
applications. It was adopted as a generic name for these steels and now covers a
wide range of steel types and grades for corrosion or oxidation resistant
applications.
Stainless steels are iron alloys (low-carbon steel) to which chromium has
been added. The minimum is 10.5% chromium, although amounts greater than 12% are
really necessary to add strength and provide its corrosion-resisting properties.
Other alloying elements are added to enhance the structure and properties such
as formability, strength and cryogenic toughness. These include metals such as:
nickel, molybdenum, titanium, copper.
Non-metal additions are also made, the main ones being: carbon, nitrogen.
The selection of a particular "type" and "grade" of
stainless steel must initially meet the corrosion resistance requirements.
Additional mechanical or physical properties may also need to be considered to
achieve the overall service performance requirements.
Specifications/grades of stainless steel used for winery equipment:-
Austenitic stainless steels are non-magnetic. Their main alloying elements are chromium (typically 18%) and nickel, which increases their corrosion resistance. They are the most widely used family of stainless steels. Examples of austenitic grades are 304/304S31 (1.4301), 304L/304S11 (1.4307), 316/316S31 (1.4401) and 316L/316S11 (1.4404).
The austenitic and ferritic stainless steels used for cutlery and holloware are: 18/8 (18.8 or 18-8), 18/10 (18.10 or 18-10) and 18/0.
Duplex stainless steels are used where combinations of high strength and corrosion resistance are needed. Examples of duplex grades are 2205 / 318S13 (1.4462) and 1.4501.