Will sheet steel that is to be used in the manufacture of automobile parts form the parts for which it is intended without breaking, buckling or pulling coarse at the sharp corners is a question, the answer to which is sought through a series of tests applied to samples of the material by the Packard Motor Car Co. Three sheets are selected from different parts of every 1000 sheets received. After sections have been removed from the ends of these sample sheets, four test pieces are taken from each sheet at specified locations and these last samples are subjected to Erichsen, Rockwell and tensile-strength tests, each of which is discussed.
The general conclusions reached are that if the Erichsen values are uniformly more than 10.3 mm., if the Rockwell hardness B-scale is between 25 and 40, the elastic-limit-tensile-strength ratio not more than 60 per cent, the elongation about 30 per cent, the microstructure of normal and uniform grain-size, the grain boundaries are sharply defined and the steel is clean, no trouble in forming deep-drawn stampings may be anticipated.
