ROUGH SHAPE MATERIAL FOR VACUUM CARBURIZATION AND METHOD FOR PRODUCING THE SAME

To provide a rough shape material for vacuum carburization in which abnormal grain growth during vacuum carburization is surely suppressed, and to provide a method for producing the same.SOLUTION: Provided is a rough shape material for vacuum carburization, which has a chemical component composition containing, in mass%, C: 0.13 to 0.28%, Si: 0.01 to 1.20%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.050% or less, Cr: 0.30 to 2.20%, Mo: 0.60% or less (including 0%), Al: 0.027 to 0.090%, and N: 0.0060 to less than 0.0140%, and in which the balance is Fe and unavoidable impurities as well as the following equation (1) is satisfied. The number of AlN precipitates having a circle-equivalent diameter of 100 nm or more in the cross section is 1.5 pieces/100 μm2 or less. Al×N≤0.00090...(1), where the element symbol in the equation (1) indicates the value of the content percentage (mass%) of each element.SELECTED DRAWING: Figure 1 【課題】真空浸炭時の異常粒成長を確実に抑制した真空浸炭用粗形材及びその製造方法を提供しようとするものである。【解決手段】真空浸炭用粗形材である。質量％で、Ｃ：０．１３〜０．２８％、Ｓｉ：０．０１〜１．２０％、Ｍｎ：０．１０〜１．５０％、Ｐ：０．０３０％以下、Ｓ：０．０５０％以下、Ｃｒ：０．３０〜２．２０％、Ｍｏ：０．６０％以下（０％を含む）、Ａｌ：０．０２７〜０．０９０％、Ｎ：０．００６０〜０．０１４０％未満を含有し、残部がＦｅ及び不可避的不純物よりなると共に、下記式（１）を満足する化学成分組成を有する。断面における円相当径１００ｎｍ以上のＡｌＮ析出物が１．５個／１００μｍ2以下である。 Ａｌ×Ｎ≦０．０００９０ ・・・（１）ただし、式（１）中における元素記号は、各元素の含有率（質量％）の値を示す。【選択図】図１