The present invention relates to an
alloy steel for low temperature vacuum
carburizing, and more particularly, to an
alloy steel for low temperature vacuum
carburizing, wherein, where the thermal
processing of
carburizing and
quenching is performed at 810° C. or so of an available minimum carburizing temperature of a conventional vacuum carburizing furnace, it is able to securing an adequate ferrite phase (α) to improve the
thermal distortion according to the thermal
processing of an annulus gear, and to satisfying shape restrictions such as a roundness or a cylindricity of the annulus gear to be manufactured. An
alloy steel for a low temperature vacuum carburizing according to the present invention, the
alloy steel is composed of a chief element of Fe, wherein the
alloy steel is formed so that dissolved
oxygen (DO) is 10 ppm or less in an alloy
system which comprises 0.17˜0.24 weight percent of C, 0.8˜1.2 weight percent of Cr, 0.4˜0.8 weight percent of Mn, 0.80˜1.20 weight percent of Si, 0.020 weight percent or less of P, 0.020 weight percent or less of S, 0.015˜0.045 weight percent of V, and the remaining weight percent of Fe.