Is A36 steel any good? What the datasheet actually promises
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TL;DR: A36 is a cheap, weldable, forgiving structural steel with a guaranteed minimum yield of 250 MPa. It is heavy for its strength and it rusts. In anything that moves or flies it loses; in a frame or a base plate it is hard to beat. The situation: A36 is the default structural steel in much of the world, and its datasheet is refreshingly simple. In our archive: minimum yield 250 MPa (36 ksi), tensile 400 to 550 MPa (58 to 80 ksi), elongation 18 to 21 % (SSAB), density 7.8 g/cm3, stiffness 200 GPa. What should you read into that? It is a minimum-yield steel, not a performance steel The yield figure is a floor the mill has to meet, and the plate on your bench can come in above it. If your strength margin is thin, a floor is not a promise about your plate, so ask for the certificate. For its strength it is heavy Compare 6061-T6 aluminium in the same archive: 276 MPa yield at 2.7 g/cm3. A36's yield is a little lower than that, at nearly three times the density (7.8 against 2.7). In a bridge or a building frame weight is not the point, and A36 wins on cost, availability and weldability. In anything that moves or flies, it loses badly. The elongation matters 18 to 21 % means the steel stretches visibly before it lets go, which is a big part of why structural codes are comfortable with it: an overloaded member usually gives you a warning in the form of a bend instead of a sudden break. A harder, higher-strength steel can trade some of that forgiveness away. It rusts A36 is plain carbon steel, so it needs paint, galvanizing or a protected environment. One detail I find useful: A36's 250 MPa yield is higher than annealed 304 and 316 stainless (205 MPa each in our tables). When you pay more for stainless you are paying for corrosion resistance and non-magnetic behaviour, not for strength. Where I would use it: frames, base plates, brackets, fixtures and welded structures where mass and corrosion are handled some other way. Where I would not: weight-critical parts, anything wet and unpainted, and anything that needs guaranteed toughness at low temperature without checking the details first. What is the most surprising place you have seen A36 used, or misused?