Patent ID: 7005017

Claim:
A method of hot-shaping a steel part, which comprises obtaining a billet of steel with the following composition in percentages by weight: 0.35%≦C≦1.2% 0.10%≦Mn≦2.0% 0.10%≦Si≦3.0% traces≦Cr≦4.5% traces≦Mo≦2.0% traces≦Ni≦4.5% traces≦V≦0.5% traces≦Cu≦3.5% with Cu≦Ni %+0.6 Si % if Cu≧0.5% traces≦P≦0.200%, traces≦Sn≦0.150%, traces≦As≦0.100%, traces≦Sb≦0.150%, with 0.050%≦P %+Bi %+Sn %+As %+Sb %≦0.200%, traces≦Al≦0.060% traces≦Ca≦0.050% traces≦B≦0.01% traces≦S≦0.0200% traces≦Te≦0.020% traces≦Se≦0.040% traces≦Pb≦0.070% traces≦Nb≦0.050% traces≦Ti≦0.050% the remainder being iron and impurities resulting from the manfacture; heating the billet to an intermediate temperature between its solidus temperature and its liquidus temperature under conditions such that the solid fraction of the billet has a globular structure; thixoforging the billet so as to obtain the said part; and cooling the said part.