Modification of ledeburite microstructure on impeller blades by mean of heat treatment

International Seminar on Metallurgy and Materials

Purwadi, W.^1 ; Idamayanti, D.^1

Foundry Engineering Department, Politeknik Manufaktur Bandung, Indonesia^1

关键词: Gray cast iron;    Impeller blades;    Mass fraction of irons;    Rapid cooling;    Variation of wall thickness;    Water pump;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/541/1/012029/pdf
DOI  :  10.1088/1757-899X/541/1/012029

来源: IOP

【 摘 要 】

Water pump machine impeller is made of gray cast iron with some variation of wall thickness. The thin part undergoes consequently a very rapid cooling and promotes the formation of hard ledeburite, This study removes the already formed ledeburite ((α + Fe3C) + Fe3C) by mean of heat treatment. By calculating the mass fraction of iron carbide at the level of 5%, heating the material at the austenite temperature, holding it for 2 hours and cooling it subsequently in the air, ledeburite changes to ferrite and graphite. Graphite is formed discrete along the grain boundaries of previous pearlite after the completion of heat treatment. The graphite resembles a randomly oriented eutectic undercooling type D and this is associated with a decrease of hardness to 115HV at the tip of the impeller blade.