Abstract: The steel according to the invention is characterized in that, in order to keep its weight content of molybdenum below 0.45%, its chemical composition, besides the iron and the inevitable residual impurities that result from the smelting of the steel, corresponds to the following analysis, given as percentages by weight: 0.3?C %?0.5 0.20?Mo %<0.45 0.4?Mn %?1.0 0.4?Cr %?2.0 0.04?Ni %?0.8 0.02?Nb %?0.045 0.03?V %?0.30 0.02?Ti %?0.05, with Ti>3.5 N 0.003?B %?0.005% S %?0.015 P %?0.015, and optionally 0.05?Si %?0.20; Al %?0.05 and N %?0.015. By cold forming a hot-rolled wire rod resulting from continuous casting, it is possible to obtain, after heat treatment, “ready-to-use” coined parts, such as cap screws for example for the automotive industry, that offer a tensile strength from 1200 to more than 1500 MPa while having a good hydrogen embrittlement resistance, and this with a specially controlled “raw material” production cost.
Type:
Grant
Filed:
April 9, 2008
Date of Patent:
November 24, 2015
Assignee:
ArcelorMittal Gandrange S.A.
Inventors:
Bernard Resiak, Mario Confente, Renë Cathiard, Bernard Starck