Ball-mill grinding kinetics of master alloys for steel powder metallurgy applications

The grinding kinetics of three newly developed master alloys for steel powder metallurgy applications were investigated using a laboratory ball-mill. Non-first order grinding kinetic is observed for the three master alloys as the breakage rate increases with grinding time due to the work hardening of the ductile phase in the microstructure. Agglomeration of fine particles is observed after a critical time at which d90 reaches its lowest value (~ 30 μm). Critical times are related to the hardness and the microstructure of the different master alloys. Agglomeration of fine particles can be overcome with the use of a process control agent. In this study, the addition of stearic acid to master alloy powders prior to grinding successfully eliminates agglomeration for long grinding times (d90 ~ 16 μm after grinding for 270 min).

The grinding kinetics of three newly developed master alloy powders were investigated using a laboratory ball-mill. Non-first order kinetics and agglomeration/aggregation of fine particles after a critical time is observed for the three powders. The use of stearic acid as a process control agent enhances the fineness of the powders for long grinding times.Figure optionsDownload as PowerPoint slideResearch Highlights
► The grinding kinetics of three master alloy powders is presented.
► Non-first order grinding kinetic is observed for the three powders.
► Grinding kinetic of the three master alloys is model by the batch grinding equation.
► Critical grinding time depends on the microstructure of the master alloy powders.
► Stearic acid as a process control agent enhances the fineness of the ground powders.