IRON-BASED ALLOY SINTERED BODY AND ITS MANUFACTURING METHOD

To provide an iron-based sintered body having high strength and high rigidity as sintered and its manufacturing method.SOLUTION: An iron-based alloy sintered body characterized in that a component composition includes Mo: 0.5 mass% or more to 2.0 mass% or less, Cu: 1.8 mass% or more and 10.2 mass% or less, and C: 0.2 mass% or greater and 1.2% or less, a remainder consists of Fe and inevitable impurities, and a microstructure is made of lower bainite, lower bainite and upper bainite, lower bainite and martensite or lower bainite and upper bainite and martensite, the microstructure, in a relative frequency distribution of Vickers hardness provided with grades to 1000 by an increment of 100 from 0, has the largest relative frequency in any one of classes of 400 Hv or larger and smaller than 500 Hv, 500 Hv or larger and smaller than 600 Hv, 600 Hv or larger and smaller than 700 Hv, 700 Hv or larger and smaller than 800 Hv, and 800 Hv or larger and smaller than 900 Hv, and the largest relative frequency is over 0.50.SELECTED DRAWING: None 【課題】焼結ままで高強度かつ高靭性を有する鉄基合金焼結体を、その製造方法とともに提供する。【解決手段】成分組成が、Ｍｏ：０．５質量％以上２．０質量％以下、Ｃｕ：１．８質量％以上１０．２質量％以下、及びＣ：０．２質量％以上１．２質量％以下を含み、残部がＦｅと不可避不純物からなり、ミクロ組織が、下部ベイナイト、下部ベイナイトと上部ベイナイト、下部ベイナイトとマルテンサイト又は下部ベイナイトと上部ベイナイトとマルテンサイトからなり、ミクロ組織が、０から１００刻みで１０００まで階級を設けたビッカース硬さの相対度数分布において、４００Ｈｖ以上５００Ｈｖ未満、５００Ｈｖ以上６００Ｈｖ未満、６００Ｈｖ以上７００Ｈｖ未満、７００Ｈｖ以上８００Ｈｖ未満又は８００Ｈｖ以上９００Ｈｖ未満のいずれかの階級に最も大きい相対度数を有し、該最も大きい相対度数が０．５０超である、鉄基合金焼結体。【選択図】なし