The Proving Center, Aberdeen requested that metallurgical examination be conducted on six (6) 1 1/2 inch rolled homogeneous armor test plates manufactured by the Carnegie-Ilinois Steel Corporation. The six plates were tested at Aberdeen as a part of the large program on the effect of hardness on ballistic properties. The plates, therefore, were from the same heat of steel and were similarly heat treated except for the final draw temperatures which were variedto give the hardnesses desired.