Mechanical properties of metal injection moulded 316L stainless steel using both prealloy and master alloy techniques

Stainless steel 316L MIM components can be made from either prealloyed powders or from master alloys blended with carbonyl iron powder. In this study these two techniques were compared using prealloyed and master alloyed gas atomised powders of -16 mum and -22 mum sizes. Four different compounds were prepared, characterised and injection moulded into tensile bars. The bars were compared for green strength, green defects, sintered strength and microstructure. The green components are stronger when carbonyl iron powder is used with the gas atomised master alloy. This material also seems to be less susceptible to moulding defects. The sintering strength of the material produced using the prealloyed powder was higher than the master alloyed prepared material. Little difference in mechanical properties existed between the materials fabricated from gas atomised prealloyed -16 mum and the -22 mum powders. Also, the viscosity of the mixtures was higher for the -16 mum material and the master alloy mixtures than for the -22 mum gas atomised prealloyed powders.