Patent ID: 11332800

Abstract:
The invention relates to a method for internal high-pressure forming and hardening of galvanized pipes made of sheet steel in which a pre-fabricated pipe is used; the pipe has at least one inlet opening (5) and a cavity (4); the pipe is heated to a temperature above the austenitization temperature (AC3) of the respective steel alloy and after the achievement of a desired degree of austenitization, is inserted into an internal high-pressure forming tool and acted on with a pressurized medium, which is forced into the cavity (4) through the at least one inlet opening (5) until the pipe fills a predetermined mold (2) of the tool, characterized in that the forming tool is heated to a temperature between 400 and 650° C., in particular 450-550° C., and the pressurized medium is likewise heated and has a temperature of 400-650° C.; after the austenitization, the pipe is allowed to passively cool or is actively cooled to a temperature of 400-600° C., but a temperature above the martensite starting temperature (Ms) of the selected steel alloy, and the cooling of the pipe for hardening purposes only takes place after the removal from the mold.