Stainless steel is one of the most popular materials used in solar fasteners. Prized for its resistance to corrosion and durability under stress, austenitic stainless steel is widely used in many different construction projects, including solar panels, wind turbines and other alternative energy equipment and structures. |
There are other types of stainless steel available for fasteners and other components, and a wise designer or purchasing manager needs to understand the difference. Take a closer look at austenitic and ferritic stainless steel and learn to recognize the advantages and disadvantages of each grade.
Austenitic Stainless Steel Solar Fasteners
About 70 percent of S.S. fasteners on the market are made from austenitic grade stainless. This grade must contain no more than 0.15 percent carbon and at least 16 percent chromium (which creates the high levels of corrosion resistance). Manganese or nickel (or a combination of both) must be included in amounts sufficient to retain the structure within a stated temperature range.
You will find austenitic stainless steel fasteners labeled with a 300 series mark. The most common type is 304, also called A2 stainless. Another common type is 316, which is designated for marine applications and works well in solar projects located in or near a water source. Other applications label the stainless steel used in a ratio of chromium/nickel-including 18/10 (containing 18 percent chromium and 10 percent nickel) or 18/8.
What About Superaustenitic Stainless Steel?
This grade of stainless offers superior protection against crevice corrosion (often a problem between the nut and mating surface) and chloride pitting (an issue commonly battled in marine applications). Superaustenitic stainless steel also endures higher levels of stress without cracking when compared to the 300 series of stainless.
Designers may specify superaustenitic grade stainless steel for solar fasteners, but these components are expensive and difficult to source. The 300 series does provide adequate strength and durability for most solar applications.
Understanding Ferritic Stainless Steel
Ferritic grade stainless steel is less expensive than austenitic grades. It has improved engineering properties, making it a good choice for fasteners, but ferritic grades also tend to have lower levels of chromium and less resistance to corrosion. The alloy does not contain significant nickel, while some types of ferritic stainless steel contain lead and most also have molybdenum.
Look for these grades of ferritic stainless steel:
. 18cr/2mo . 26cr/1mo . 29cr/4mo
Duplex Stainless Steel
This grade of stainless includes austenitic and ferritic grades in a mixture of roughly equal parts. Several advantages of this combination could be realized in solar fasteners, including higher levels of durability and better resistance to corrosion when compared to ferritic. Duplex contains less nickel than austenitic and also has molybdenum in small amounts (not more than 5 percent).
Stainless steel continues to offer premium performance in solar fasteners, providing excellent resistance to corrosion with very little maintenance. Aluminum is another good choice for solar energy systems, but austenitic or 300-series stainless remains at the top of the list for structural and mechanical components and fasteners. Be sure to consider superaustenitic or duplex stainless steel when manufacturing custom solar fasteners, should the benefits of these grades improve your system design.
Mike Moore is published on more than 300 websites. He writes about industrial fasteners and building, commercial building, and home building projects . He is published on various website including http://www.melfast.com
Related Articles -
solar fasteners, nuts and bolts, hex bolts,