| 摘要 |
PROBLEM TO BE SOLVED: To provide case hardening steel capable of producing a high precision gear. SOLUTION: The case hardening steel is produced by continuous casting, and provided that the microsegregation degrees of C and Mn in the cross-section in the radial direction of a slab are prescribed by both of a difference between the maximum value and the minimum value in all measuring points obtained by measuring the contents of the respective elements on a plurality of equally divided lines on the cross-section in the radial direction of the slab and a difference in the contents in the measuring points adjoining on a plurality of the equally divided lines, the difference between the maximum value and the minimum value is≤0.03%, the difference in the contents at the adjoining measuring points is≤0.02%, and preferably, the slab has a componential composition comprising, by mass, 0.10 to 0.35% C, 0.03 to 2.5% Si, 0.20 to 2.50% Mn, 0.01 to 2.50% Cr, 0.01 to 0.70% Mo, 0.01 to 2.0% Ni, 0.005 to 0.1% Al and 0.0040 to 0.0250% N, and, if required, added with one or more selected from W, V, Ti, Nb, Zr and B. COPYRIGHT: (C)2006,JPO&NCIPI
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