The chromium takes care of corrosion and heat resistance. Corrosion resistance is due to the presence of a naturally occurring chromium-rich oxide film on the steel’s surface. This inert film adheres tightly to the metal and is rapidly self repairing in the presence of oxygen or surface damage.
The other alloys in stainless steel also enhance corrosion resistance and impart certain characteristics with respect to strength and fabricability.
Stainless steel as used in fastener manufacture is normally identified by the following three terms on the basis of their metallurgical structure. Under each classification the material tends to have similar characteristics with regards corrosion resistance, hardenability and fabricability.
When these types have been considered on the basis of their corrosion-resistant properties the next concern will be their tensile strength or its capacity to withstand load. See the following chart.
For a fastener to be effective it will be obvious to the designer the fastener must be installed correctly. Incorrect installation can lead to difficulty such as seizing and galling or alternatively the fastener may work loose with vibration. Reasonable care should be taken in handling fasteners to ensure threads are kept clean and free of dirt. It is also critical that the fastener is installed to the correct torque. Trouble occurs in this area when fastener installation is attempted without correct torque measuring tools.