| For the purpose of investigating the applicalibity of AISI TI5 grade high speed steel for metal injection molding. The mixed elemental and prealloyed powders were sintered in a vacuum and N₂-20%H₂ atmosphere. The debinding rates of the prealloyed and the mixed elementa powder were 92.5% and 105.3%, respectively. It is considered that the fine pores existed on the surface of the prealloyed powder caused the binder to remain in the powder by a capillary action during the debinding process. The carbon contents of the prealloyed and mixed powder were 2.01wt.% and 1.79Wt.%, respectively, after debinding. When sintered at an optimum temperature in a vacuum, the rate of carbon loss after the sintering for the prealloyed and mixed elemental powder showed a little difference of 19.5% and 17.9%, respectively. When sintered in N₂-20%H₂ atmosphere the carbon loss for the mixed elemental powder was found too high, over 86%, to effectively control the carbon content. The maximum sintered densities after the vacuum sintering were above 97% for both mixed and prealloyed powder whereas the sintered densities of the mixed and prealloyed powder after N₂-20%H₂ sintering were 94% and 77.1%, respectively. Therefore it was difficult to apply the prealloyed powder into the metal injection molding process in the atmosphere of N₂-20%H₂gas. |
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