Patent ID: 7754031

Claim:
Weldable component of structural steel, wherein the chemical composition comprises, by weight: 0.10%≦C≦0.22% 0.50%≦Si≦1.50% 0%<Al≦0.9% 0%≦Mn≦3% 0%≦Ni≦5% 0%≦Cr≦4% 0%≦Cu≦1% 0%≦Mo+W/2≦1.5% 0.0005%≦B≦0.010% 0%<N≦0.025% optionally at least one element selected from V, Nb, Ta, S and Ca, at contents of less than 0.3%, and/or from Ti and Zr at contents of less than or equal to 0.5%, the remainder being iron and impurities resulting from the production operation, the contents of aluminium, boron, titanium and nitrogen, expressed in thousandths of %, of the composition also satisfying the following relationship: B ≥ 1 3 × K + 0.5 ⁢ , ( 1 ) with K=Min (I*; J*) I*=Max (0; I) and J*=Max (0; J) I=Min (N; N−0.29(Ti−5)) J=Min (N; 0.5(N−0.52 Al+√{square root over ((N−0.52 Al) 2 ÷283)})), the contents of silicon and aluminium of the composition also complying with the following conditions: if C>0.145, then Si+Al<0.95; whose structure is bainitic, martensitic or martensitic-bainitic and also comprises from 3 to 20% of residual austenite; and the chemical composition also satisfies the following relationship: % Cr+3(% Mo+% W/2)≧1.8.