High speed steel specimens were worked by torsion at the temperature of 1000∼1200°, and austenite grain-growth was observed with microscope. Austenite grain-boundaries were revealed by keeping the specimens at 800° for 10 minutes, the temperature bringing the nose in S curve. The outlines of the experiments are as follows :
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oindent(1) The relation between the degree of deformation, grain size and the working temperature was measured.
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oindent(2) The progress of recrystallization or grain-growth with the lapse of time after hot working was observed.
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oindent(3) The relation between the degree of deformation and the lapse of time before recrystallizing was found out.
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oindent(4) It was observed that the successive alternating working diminished the capacity of recrystallization.
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oindent(5) Coarse austenite grains were incapable of being recovered by the heat treatment.
