Disclosed is a free-cutting steel containing Ti- and/or Zr-carbosulfide as
inclusion and having good machinability both in turning and drilling. The
free-cutting steel consists essentially of, in mass %, C: 0.05-0.80%, Si:
0.01-2.5%, Mn: 0.1-3.5%, Ti+0.52Zr: 0.03-1.2%, S:0.015-0.6% and the
balance of Fe and inevitable impurities, and is characterized in that the
contents of Ti, Zr and S meet the condition of (Ti+0.52Zr)/S<2. The
free-cutting steel may contain, in addition to the above basic alloy
composition, Ca: 0.0005-0.02% and/or Mg: 0.0003-0.02%. The latter steel
exhibits much more improved machinability.
Révélé est un acier facile à couper contenant le Ti et/ou le Zr-carbosulfide comme inclusion et ayant la bonne usinabilité dans la rotation et le forage. L'acier facile à couper consiste essentiellement en, en % de masse, C : 0.05-0.80%, silicium : 0.01-2.5%, manganèse : 0.1-3.5%, Ti+0.52Zr : 0.03-1.2%, S:0.015-0.6% et l'équilibre du Fe et des impuretés inévitables, et est caractérisé parce que le contenu du Ti, du Zr et du S rencontre la condition de (Ti+0.52Zr)/S
