Castings ordered and produced in accordance with this
specification are classified into a number of grades based on the
properties of separately cast test bars (Table 1, Table 2). Each
class is designated by a number followed by a letter. The
number indicates the minimum tensile strength of the separately
cast test bar, and the letter indicates the size of the test
bar. Examples of proper designations are as follows:
Gray Iron Castings, ASTM Specification A48, Class 30B.
Gray Iron Castings, ASTM Specification A48, Class 40C.