CAST IRON PIPE AND METHOD FOR PRODUCING CAST IRON PIPE

Japanese Patent JP2022149444

A

To provide a cast iron pipe that does not cause a coating defect in an inner surface treatment process, at low cost.SOLUTION: The cast iron pipe includes: a graphite layer 2 that contains spheroidized graphite 4; and a decarburized layer 3 that is formed in a region closer to the inner surface of a pipe body than the graphite layer 2 and contains the spheroidized graphite 4 having a relatively lower density than the density of the spheroidized graphite 4 in the graphite layer 2. A method for producing the cast iron pipe includes: an annealing step of forming the graphite layer 2 that contains the spheroidized graphite 4 and the decarburized layer 3 that contains the spheroidized graphite 4 having a relatively lower density than the density of the spheroidized graphite 4 in the graphite layer 2, in the region closer to the inner surface of the pipe body than the graphite layer 2, by subjecting the pipe body that has been formed by a centrifugal casting method, to annealing heat treatment; and a removal step of exposing the decarburized layer 3 to the inner surface of the pipe body, by removing a defective layer which has been formed in a region closer to the inner surface of the pipe body than the decarburized layer 3 in the annealing step.SELECTED DRAWING: Figure 1

JPH0617186	SPHEROIDAL GRAPHITE CAST IRON MEMBER AND MANUFACTURE THEREOF
JPS6462439	CASTING OF SPHEROIDAL GRAPHITE CAST IRON HAVING EXCELLENT MACHINABILITY

NISHIHARA YOSHIKAZU

JP2021051611A

October 06, 2022

March 25, 2021

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KURIMOTO LTD

C22C37/04; B22D13/02; B24B5/40; C21D9/08

Naoya Kamada
Bunji Kamata
Yaichiro Nakatani
Masanori Akatsuka

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