抄録
During the past ten years many researches to shorten the time of malleablising have been done both in Japan and foreign countries. More than seventy hours annealing, however, is necessary for graphitising of ordinaruy white cast iron in nowadays.
Recent publication have described that the quenched white cast iron graphitise in shorter times compare to other ordinary white cast irons with no treatment.
But these treatments can not be applied to industrial production method because of its quenching crack in various section which are particulary sensitive to cooling speed. Another report noted on the short cycle malleable cast iron using centrifugal casting.
Casting molten white iron in metal mold also shorten its graphitising time comparatiyely.
Both these malleable cast irons, however, were not med for industrial application in these days. This paper report that pouring in metal mold the molten iron, which would show in green sand mold a mottled iron flacture, shorten the malleableising cycle remarkably.
By using metal mold and sand core, we could get an pipe union having micrographic structure of black heart malleable, temper carbon and ferrite ground, only by five or six hours annealing in laboratory.
