The effect of annealing temperature and holding time on the mechanical properties of pure titanium castings was investigated by means of microhardness test, compression test, microscopic observation, and EDS. Casting process was carried out under
argon
gas and the heat treatment was carried out under air. The results were as follows :
1. The mechanical properties of the specimens heat-treated at 500, 750℃ were slightly increased, but those of specimen heat-treated at 1,000℃ were remarkably increased by prolonged holding time.
2. The microstructures of specimens heat-treated at 500, 750℃ were bulntly serrated α struture, but that of specimen heat-treated at 1000℃ showed the mixture of acicular α and platelike α structurers with a great number of fine
precipitates.
3. The surface reaction layer was gradually thinned away by prolonged holding time at 1,000℃, Al and Si elements of the surface reaction layer were homogeneously diffused to the inside of the specimen.
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