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Stainless Steel Grades & Finishes

Stainless Steel Finishes

Stainless steel is a popular material for sheet metal production. Stainless steels are iron-based alloys that contain at least 10% chromium to bring unique benefits such as high resistance to corrosion, heat and oxidisation.
In comparison with other metals used in sheet metal fabrication, stainless steel is highly durable.

Stainless steel sheet can vary in grades and finishes, all of which will affect the properties of the metal and so, to fabricate highly precise, durable components that use the material's advantages, many factors need to be considered.

Stainless steel grades

The grades of stainless steel most used in sheet metal fabrication include 304, 316 & 430.

304-grade stainless steel contains 18% chromium and 8% nickel and offers low-cost corrosion resistance to oxidisation, versatility and ease of fabrication. 304 stainless steel is austenitic and is often used to fabricate indoor products such as electrical enclosures, kitchen equipment and stainless hardware.

316-grade stainless steel contains 2% molybdenum, which strengthens its resistance to chlorides, sea water, acidic chemicals and heat. 316 stainless steel is therefore favoured for the manufacture of outdoor products and those placed in testing environments such as marine applications or oil equipment.

430 Stainless is a ferritic stainless steel with good corrosion resistance (however less than 304) and particularly strong resistance to nitric acid. The stainless is readily weldable, ferromagnetic, has high machinability and is less expensive than the austenitic grade 304. 430 is commonly used for domestic appliances, automotive trim products and metal fabrications for chemical applications.

Stainless Steel Finishes

When selecting a stainless-steel finish, it's important to consider the application of the product and understand that each finish will provide a different cosmetic appearance, a varying level of corrosion resistance and require different levels of manufacturing which may impact the cost.

A rough surface finish can easily diminish the corrosion resistance of high-grade stainless steel.

The benefits of each stainless-steel finish and the suitability for application are discussed below.

Brushed steel finish

Brushed: A brushed stainless steel finish offers a non-reflective directional surface, produced by polishing the metal surface with a grit belt and then softening with adhesive. The process can roughen the surface and reduce corrosion resistance however its appealing matte cosmetic appearance makes the finish commonplace for many household applications such as kitchen sinks.

Bead blasted finish

Glass Bead Blasting: This involves blasting fine glass beads (on their own or mixed with other non-abrasive materials) on to the stainless-steel surface at high pressure. It eliminates any impurities or deposits and provides a soft a smooth, low-reflective finish. Blasting removes any visible imperfections that may have occurred during a previous fabrication process. Although susceptible to fingerprint staining, it is a relatively cost-effective finishing method. Manufacturers of medical equipment, food distribution and packaging conveyors often favour this hygienic, matte finish to metal fabricated products.

Passivated finish

Passivated: Stainless steel passivation is a finishing method that uses an acid solution to remove any contamination from the surface of the steel that may encourage rust or corrosion, for example, dirt iron particles, and to enhance the natural corrosion resistance. Stainless steel passivation usually results in a bright, smooth finish and is used in metal product fabrication for the medical and dental industries.

Mirror steel finish

Mirror Polished: Polished finishes are highly reflective, mirror-like and easy to clean. Common applications are commercial products such as forecourt equipment, catering dispensers and handrails. The finishing method is achieved from polishing with fine abrasives and comprehensive buffing.

With dedicated facilities for stainless steel fabrication, including on-site shot bead blasting and electro-mechanical assembly, KMF Precision Sheet Metal is the UK's leading sheet metal fabricator. Contact one of our experts today to discuss your stainless-steel fabrication project and which stainless steel finish option is the best choice for your products.

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