FIELD: metallurgy.
SUBSTANCE: invention refers to metallurgy. To upgrade hardenability and weldability a welded part is produced out of steel, wt %: 0.40≤C≤0.50, 0.50≤Si≤1.50, 0≤Mn≤3, 0≤Ni≤5, 0≤Cr≤4, 0≤Cu≤1, 0≤Mo+W/2≤1.5, 0.0005≤B≤0.010, N≤0.025, Al≤0.9, Si+Al≤2.0, if necessary, at least one element chosen out of the group V, Nb, Ta, S and Ca with contents (wt %) less, than 0.3 and/or out of Ti and Zr with contents less or equal 0.5, iron and impurities, formed at welding - the rest; at that values of contents AL, B, Ti, N expressed in thousandths shares % of the said composition meet the following ratio: 
at K=Min(I*; J*), I*=Max (0; I) and J*=Max (0; J), l=Min(N, N-0.29(Ti-5) J=Min (N; 0.5(N-0.52 Al+
). The part has bainitic, martensite or martensite-bainitic structure, additionally containing from 3 to 20% of residual austenite. The method of fabrication of the welded part of the above said composition includes heating of the part to the temperature of austenitising within the range from Ac3 to 1000°C preferably from Ac3 to 950°C, then cooling to the temperature less or equal 200°C in such a way that in the core of the part the rate of cooling from 800°C to 500°C exceeds or is equal to the critical bainitic rate; if necessary annealing is performed at the temperature less or equal to Ac1.
EFFECT: upgraded hardenability and weldability of welded steel part.
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