Aluminum is non-magnetic and sometimes used as structural members in construction projects. The weight of aluminum is roughly 1/3 the weight of steel, but the yield strength is also roughly 1/3 that of steel. Aluminum also resists corrosion well. Aluminum is actually an element in the periodic table, but pure aluminum has a very low tensile strength and is rarely used. Most products called aluminum are actually aluminum alloys, produced by combining aluminum with small amounts of some of the following: copper, zinc, magnesium, manganese, tin, titanium, lithium, silicon, etc.
So as a light weight metal that is resistant to corrosion, aluminum
has many uses on a construction project. The typical shapes and their
sizes and attributes are shown at this website, as well as excellent
descriptions of attributes of various available alloys:
Stainless steel also has many uses in the construction field, normally when corrosion resistance is required. The various types of stainless steel do not stain, corrode or rust as easily as regular steel. Stainless steel has a minimum of 10% chromium content and there are at least 15 different common grades of stainless steel available. The typical shapes and their sizes and attributes are shown at this website: http://www.stainless-structurals.com/.
All the steels and irons mentioned above are magnetic, except certain
types of stainless steel. When stainless steel has significant amounts
of nickel added, the resulting metal is non-magnetic.