| 摘要 |
PROBLEM TO BE SOLVED: To provide free cutting tool steel which has excellent machinability, and in which anistropy is hard to occur in mechanical properties in the cogging direction of the stock, particularly, in toughness. SOLUTION: The steel contains Fe, 0.001 to 0.6 mass% C, <=6 mass% Ni <=5 mass% Cu and <=3 mass% Al. Provided that the content of Ti is defined as WTi (mass%), and the content of Zr as WZr (mass%), Ti or Zr is contained so that X (mass%)=WTi+0.52WZr is controlled to 0.03 to 3.5 mass%. Further, provided that the content of S is defined as WS (mass%), the content of Se as WSe (mass%), and the content of Te as WTe (mass%), one or more kinds selected therefrom are contained so that Y (mass%)=WS+0.4WSe+0.25WTe is controlled to 0.01 to 1 mass%. A free cuttability impartion compound phase containing Ti and/or Zr as the main component of metallic element components, and, as bonding components, essentially consisting of C, and containing at least any of S, Se and Te is dispersedly formed in the structure.
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