Each month, Stainless Solutions from IMOA covers a different stainless steel issue with tips on design and specification, and links to technical resources. This month they discuss Austenitics, the family of stainless steels that are most commonly used for architecture.
The austenitic stainless steels have been the primary alloys used for building and construction, consumer products and industrial applications. Their overwhelming popularity is due to several factors:
• Commonly available in all sizes and product forms;
• Highly formable, making very tight crisp bends possible;
• Easy to weld and repair;
• Widest range of aeshetic finishes; and
• Superior impact, blast and seismic performance
The most commonly used alloys have been Types 304 and 316 and their low carbon versions Types 304L and 316L. The low carbon versions are only needed when sections 0.125 inches (3.2 mm) thick and greater will be welded. The molybdenum addition to Types 316/316L makes them more resistant to chloride salts (coastal and deicing) and to pollution related corrosion.
Early architectural projects, built some 50 or more years ago, were constructed in Type 302, which is equivalent to modern Type 304. While Types 304/304L and their predecessor Type 302 were widely used historically for building and construction applications, Type 316/316L and sometimes more corrosion-resistant stainless steel alloys are increasingly being specified for exterior and sheltered applications.
This has occurred because of increasing global use of deicing salts, population concentration in coastal areas, and high pollution levels and rain acidity in developing countries. Sheltered areas are even more corrosive because they accumulate the same environmental contaminants but do not benefit from natural rain-washing. Austenitic grades with even greater corrosion resistance are used for industrial and seawater applications.
IMOA’s Stainless Steel Selection System, Case studies, Coastal Salt, Deicing Salt and other website resources provide alloy selection guidance. Visit this link to view those resources and the complete newsletter.
For more information or to schedule a workshop contact Catherine Houska, 412-369-0377.