METHOD OF THERMAL TREATMENT OF WELDED CONNECTIONS FROM MARAGING STEELS Russian patent published in 2004 - IPC

FIELD: thermal treatment of maraging steels welded connections.

SUBSTANCE: the invention is pertinent to the field of thermal treatment of the structures made out of dispersion-hardening steel alloys and working in conditions of both high and low temperatures, vibrations and hostile environments, in particular to the thermal treatment of the soldered - welded structures containing details made out of a maraging steel such as Н18К8М5Т. The technical result of the invention is restoration of 90 % ultimate stress limit of a welded seam of an item made out of the basic aged material - namely the steel of Н18К8М5Т type under condition of heating the whole item up to 80°С, and also for a case when heating of the whole item is not circumscribed. The technical result is achieved by the fact, that a welding of a joint of an aged material - steel of Н18К8М5Т type - is performed by a 1400±100 W focused electronic beam with a speed of 25±2 mm/s. Then the item is cooled down in vacuum up to ambient temperature, then it is treated with liquid nitrogen, then it is subjected to isothermal annealing at the temperature of 480±5°С during 3.5±0.5 minutes and again it is cooled down to the ambient temperature. In the cases, when heating of the whole item should not exceed 80°С, the isothermal annealing is substitute for a local multicycled heating of the seam by a defocused electron beam up to 480+5°С, cooled down to ambient temperature. At that the total time of the welded connections kept at the temperature of 480±5°С is no less than 3.5 ± 0.5 minutes.

EFFECT: the invention ensures restoration of 90 % ultimate stress limit of a welded seam of an item made out of the steel of Н18К8М5Т type.

3 cl, 2 dwg, 1 ex