STEEL FOR MECHANICAL CONSTRUCTION, METHOD OF HOT-SHAPING OF A PART FROM THIS STEEL, AND PART THUS OBTAINED.

摘要

The invention relates to a steel for mechanical construction, wherein its composition in percentages by weight is: 0.35%C1.2%; 0.10%Mn2.0%; 0.10%Si3.0%; tracesCr4.5%; tracesMo2.0%; tracesNi4.5%; tracesV0.5%; tracesCu3.5% with CuNi %+0.6 Si % if Cu0.5%; tracesP0.200%, tracesBi0.200%, tracesSn0.150%, tracesAs0.100%, tracesSb0.150%, with 0.050%P %+Bi %+Sn %+As %+Sb %0.200%, tracesAl0.060%; tracesCa0.050%; tracesB0.01%; tracesS0.0200%; tracesTe0.020%; tracesSe0.040%; tracesPb0.070%; tracesNb0.050%; tracesTi0.050%; the remainder being iron and impurities resulting from the manufacture. The invention also relates to a method of hot-shaping a steel part, wherein: a billet of steel of the preceding composition is obtained; it is heated to an intermediate temperature between its solidus temperature and its liquidus temperature under conditions such that the solid fraction has a globular structure, and thixoforging of the said billet is carried ou t so as to obtain the said part; and cooling of the said part is carried out. Finally, the invention relates to a part made from thixoforged steel, wherein it has been produced by the preceding method.