AISI Type P4 is an alloy steel that develops exceptionally high strength which is retained at operating temperatures to 800 F. In the annealed condition (maximum Brinell hardness 135), cavities can be machined readily or produced by cold hobbing if the impressions are not too deep. Type P6 takes a high-luster finish if carburized to the proper surface carbon content; the maximum carbon content is 0.50% for the die-casting dies and 0.80-1.00% for molds for plastics. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: TS-399. Producer or source: Tool steel mills.