Stainless Steel Material Information
Stainless Steel is a metallic alloy having iron as the base metal with significant amount of chromium addition. The carbon content of this steel is usually low and can go to a maximum of 1.2% carbon. Chromium content can greatly vary but in order to be a stainless-steel, a minimum chromium content must be 11% or greater. Due to significant chromium content, chromium atoms are able to disperse throughout the matrix and protect the surface by forming a thin passive layer of chromium oxide (Cr2O3). This Cr2O3 layer is grown through passivation to increase the thickness of the passive layer so that superior properties can be obtained.
Being passive in nature, stainless steel coatings are a preferred industrial choice for many parts, machines and equipment. It not only offers corrosion protection, but also increases the durability of the part. The passive oxide coating makes stainless steels immune to most oxidation attacks depending on the application of use and the environmental factors involved.
The selection criteria for stainless steel coatings is largely dependent on the application of use and the environmental factors associated with that application. Stainless steel coatings are an excellent and inexpensive choice when it comes to dry and oxygen accessible environments. In cases of high salinity and humidity, stainless steel coatings can be limiting. The addition of other alloying elements, such as molybdenum, to stainless steels can increase the corrosion resistance and improve protection against chloride environments and pitting attacks.
Properties of Stainless-Steel Coatings
- Good durability
- Superior and uniform hardness
- Excellent protection against wear assisted oxidation
- Good corrosion resistance due to formation of passive Cr2O3 layer
- Excellent oxidation resistance
- Prevention from chemical attack
- High bonding strength of thermal sprayed coating
- Low porosity
- Dense coating
- Offers excellent oxidation resistance even at elevated temperatures.
- Stainless steels coatings enhance the life span of the part by offering protection from environmental attacks
- With Cr2O3 coatings, the repair duration is extended, and maintenance work is minimized.
- Coating offers resistance against a variety of corrosion types i.e. cavitation damage, fretting, abrasion.
- Coatings is inexpensive compared to other carbide coatings.
- Coating is effective.
- Coating technology is efficient and reliable.
- Offers a good combination of mechanical and metallurgical properties.
- SS coatings are not always applicable for oxygen deficient environments as lack of oxygen hinders passive oxide layer formation.
- Not suitable to environments having high salinity and humidity.
Uses and Applications
- Stainless steel coatings find applications in several building and architectural structures including structural beams, fixtures, panels, railings, walk-ways, steel decking, doors and handles in interior and exterior settings for protection against corrosion, wear and UV attacks.
- These coating are also used for embellishment of cheap jewellery items, watches and belt buckles.
- SS coatings are also an important part of the automotive industry for auto body enhancement and protection. These coatings are used on various autobody parts e.g. spindles, arms, bumpers, suspensions, etc. They also add ease in the repair process as SS coating can be directly welded on without coating removal. The steel finish also adds a lustrous shine.
- SS coatings have also been incorporated in the food processing industry. Being non-toxic, these coating have been used for years in food processing conveyors, machines, racks and other packaging equipment to increase service life.