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I'm getting ready to order all the 4130 steel I need for the fuselage. In the plans, I see 4130N for round tubes and 4130 for plates. In the ACS website, everything is 4130 for round tubes and plates, no N. What does the N means? Can I order them without the N?
The N is for normalized....which means the metal is heated to a higher temperature and then cooled down slowly and has a higher tensile strength.
William - Normalizing is an air cool down (room temp.) process. Slowly cooling the steel (after heating beyond the critical point) would produce an annealed (softer [relative term]) product. You would be OK using 4130 for the application, normalized or not.