| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for continuously casting a free-cutting steel for a machine structure without causing an inner crack and a surface crack. SOLUTION: (1) The free-cutting steel for the machine structure comprises 0.2-0.6% C, 0.03-1.0% Si, 0.66-2.0% Mn, 0.003-0.2% P, 0.04-0.20% S, less than 0.01% Pb, 0.1% or less Al and 0.001-0.02% N, while controlling the contents of Mn and S so as to satisfy [S%]<0.31×[Mn%]<SP>5</SP>. The steel having the composition can be continuously cast. (2) The free-cutting steel for the machine structure in the item (1) may further include one or more elements selected from one or more groups of the groups (a) and/or (b), wherein the group (a) consists of Cu, Ni, Cr, Mo, V and Nb; and the group (b) consists of Ti, Se, Te, Bi, Sn, Ca, Mg and rare earth elements. COPYRIGHT: (C)2006,JPO&NCIPI
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