MICROALLOYED STEEL WITH GOOD RESISTANCE TO HYDROGEN FOR THE COLD-FORMING OF MACHINE PARTS HAVING HIGH PROPERTIES

摘要

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: 0.3C %0.5 0.20Mo %0.45 0.4Mn %1.0 0.4Cr %2.0 0.04Ni %0.8 0.02Nb %0.045 0.03V %0.30 0.02Ti %0.05, with Ti3.5 N 0.003B %0.005% S %0.015 P %0.015, and optionally 0.05Si %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.