This invention, weight % with, carbon (C)0.03 - 0.30%, silicon (Si) 0.01 - 0.30%, manganese (Mn) 0.2 - 2.0%, phosphorus (P) 0.02 - 0.10%, sulfur (S) 0.06 - 0.45%, bismuth (Bi) 0.04 - 0.20%, tin (Sn) 0.04 - 0.20%, boron (B)0.001 - 0.015%, nitrogen (N) 0.001 - 0.010%, all oxygen (T [O]) consists of 0.002 - 0.025% and remainder Fe and the inevitable impurity, machinability and the hot rolling which feature that tin, the bismuth, the sulfur, manganese, boron and nitrogen satisfy fixed relationshipIt regards the environmental friendship type unleaded free-cutting steel where characteristic is superior. According to this invention, although not to be inferior to the former lead content free-cutting steel, or possessing excellent machinability it is possible to offer the environmental make friends unleaded free-cutting steel. Because as for this invention, hot ductility being superior, it is possible, to minimize the defective occurrence of the surface the case of hot rolling, there is a big effect in improvement of hot rolling productivity.
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