AMS4598B results from a Five-Year Review and update of this specification with changes to prohibit unauthorized exceptions (3.4.1.1, 3.7, 4.4.1, 5.1.1, 8.9), correct temper designation per ASTM B601 from TX00 to TX02 (title, 3.2, 3.3.2, 8.3), create type classification for forward and back extruded products (1.3), revise size ranges for forward and back extruded product (Table 2). Revise property limits and type for product from 7.250 inches to 8.750 inches (184 mm to 222 mm) in nominal diameter (Table 2). Additional updates to form (1.1), applicable documents (Section 2, 8.5), composition (3.1), condition (3.2), solution annealing (3.3.1), spinodal hardening (3.3.2), tolerances (Table 3), ordering information (8.11), and add general agreement wording regarding the immediate prior revision of this specification to highlight changes in the product thickness ranges for the defined types in this revision (8.10).