FIELD: welding.
SUBSTANCE: group of inventions relates to a method for the production of steel billet (1), a method for the production of a steel part welded and then molded by hot pressing and cooled, welded steel billet (1), a steel part welded, molded by hot pressing, and cooled, and the use of a steel part welded, molded by hot pressing, and cooled. For the production of welded steel billet (1), two pre-coated sheets (2) are provided. Each sheet (2) includes steel substrate (3) and has preliminary coating (5) on each of main surfaces (4). Each sheet (2), on an edge of welded joint (14), includes zone (18) of removal of preliminary coating (5). Butt welding of sheets (2) is performed using filler wire (20) to create welded joint (22) having an average aluminum content AlWJ of 0.1-1.2 wt.%. A composition of wire (20) and a proportion of added wire (20) are such that welded joint (22) has: (a) a tempering factor FTWJ such that 
(b) a nickel content NiWJ of ≤ 14-3,4xAlWJ, and a chromium content of CrWJ ≤ 5-2xAlWJ, where AlWJ is an average aluminum content in welded joint (22).
EFFECT: prevention of the probability of damage to a part obtained from a steel billet, manufactured of two welded pre-coated sheets, after hot pressing and cooling in a zone directly adjacent to a welded joint of the specified welded steel billet due to elimination of brittle fracture in the welded joint, and obtainment of a part having satisfying characteristics of safety in collision, even with relatively high aluminum content in the welded joint.
47 cl, 5 dwg, 6 tbl
