SEMS Screws Stainless Steel Screws SEMS Machine Screw Metric

SEMS screws combine two separate parts into one pre-assembled, low-cost fastener. With washers under the head, SEMS screws are fast, permanent, and easily adaptable to many applications. Ever Hardware provides custom-made fasteners and customizable packaging.

Stainless steel does not readily corrode, rust or stain with water as ordinary steel does. However, it is not fully stain-proof in low-oxygen, high-salinity, or poor air-circulation environments. There are different grades and surface finishes of stainless steel to suit the environment the alloy must endure. Stainless steel is used where both the properties of steel and corrosion resistance are required.
Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film (the rust) is active and accelerates corrosion by forming more iron oxide; and, because of the greater volume of the iron oxide, this tends to flake and fall away. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal’s internal structure. Passivation occurs only if the proportion of chromium is high enough and oxygen is present.

Passivation, in physical chemistry and engineering, refers to a material becoming “passive,” that is, less affected or corroded by the environment of future use. Passivation involves the creation of an outer layer of shield material that is applied as a micro coating, created by chemical reaction with the base material or allowed to build from spontaneous oxidation in the air.