SPHEROIDAL GRAPHITE CAST IRON FOR PISTON, INTEGRATED PISTON AND MARINE ENGINE

PROBLEM TO BE SOLVED: To provide a spheroidal graphite cast iron for piston excellent in heat resistance and life while maintaining strength and hardness, an integrated piston formed by the spheroidal graphite cast iron and a marine engine with the piston.SOLUTION: The spheroidal graphite cast iron for piston according to an embodiment contains, by mass, C:2.7 to 4.3%, Si:2.0 to 3.5%, Mn:0.3 to 0.8%, Mg:0.02 to 0.10%, Cu:0.3 to 1.0%, Cr:0.05 to 0.90%, Mo:0.05 to 1.00% and the balance Fe with inevitable impurities. The C content and the Si content are in a composition range surrounded by lines connecting points of Point A(2.7%,3.5%), Point B(3.2%,2.0%), Point C(4.3%,2.0%) and Point D(3.8%,3.5%) represented by (C content, Si content) successively in a figure showing a relationship between the C content and the Si content.SELECTED DRAWING: None 【課題】強度及び硬さを維持しつつ、耐熱性及び寿命に優れたピストン用球状黒鉛鋳鉄、この球状黒鉛鋳鉄によって形成された一体型ピストン、及びこのピストンを備える舶用エンジンを提供する。【解決手段】 実施形態のピストン用球状黒鉛鋳鉄は、質量で、Ｃ：２．７〜４．３％、Ｓｉ：２．０〜３．５％、Ｍｎ：０．３〜０．８％、Ｍｇ：０．０２〜０．１０％、Ｃｕ：０．３〜１．０％、Ｃｒ：０．０５〜０．９０％、Ｍｏ：０．０５〜１．００％を含有し、残部がＦｅ及び不可避的不純物からなる。そして、Ｃ含有量及びＳｉ含有量が、Ｃ含有量とＳｉ含有量との関係を示す図において、（Ｃ含有量，Ｓｉ含有量）で示される点Ａ（２．７％，３．５％）、点Ｂ（３．２％，２．０％）、点Ｃ（４．３％，２．０％）、点Ｄ（３．８％，３．５％）の各点を順次結ぶ線で囲まれた組成範囲内にある。【選択図】なし