ULTRALUME Press Hardenable Steel (PHS) is AK Steel's newest addition to our expanding product portfolio of Advanced High Strength Steels (AHSS). Aluminized Type 1 ULTRALUME PHS is intended for automotive steel applications where high strength, design flexibility and collision protection are paramount. Blanks produced from ULTRALUME PHS are heated in a furnace at 900° to 950 °C to bring the steel into the austenitic temperature range. The blank is then transferred to a hot forming press where the hot steel is formed into complex shapes. The steel cools rapidly inside the water-cooled dies and undergoes a phase transformation from austenite to a high strength phase - martensite. This rapid cooling, or quenching, increases the tensile strength of the steel from approximately 600 MPa to 1,400 MPa and higher. Since the steel is held in the dies during cooling, thermo-distortion and springback are avoided.
ULTRALUME PHS is continuously hot dip coated on both sides of the steel. The aluminum coating bath contains approximately 91% aluminum and 9% silicon. The metallic coating is metallurgically bonded to the steel substrate and protects the steel surface against decarburization and oxidation during hot stamping. As a result, the shot blasting operation required for hot-stamped, uncoated steel parts is eliminated.