To provide a cast slab of Ti-added case hardening steel in which the formation of TiN or N-enriched TiCN inclusions with a large diameter exerting adverse influence on its machinability is suppressed.
The cast slab of a Ti-added case hardening steel with a diameter of ≤23 cm is provided which has a composition comprising, by mass, 0.10 to 0.30% C, 0.03 to 1.00% Si, 0.20 to 1.00% Mn, ≤0.025% P, 0.001 to 0.030% S, ≤0.0100% N, 0.05 to 0.20% Ti, 0.003 to 0.050% Al and ≤0.0030% O, and further comprising one or more kinds selected from 0.15 to 2.00% Cr, 0.10 to 2.00% Ni, 0.03 to 0.30% Mo, 0.0001 to 0.0020% B, 0.01 to 0.20% V and 0.01 to 0.15% Nb, and the balance Fe with inevitable impurities, wherein the maximum size √ (area max) of TiC or TiNC crystallized out at an observation area of 30,000 mm
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Yokoi Satoshi