An experimental study of size effects in sintering

Within the PM industry there is a consistent drive to create more efficient and cost effective material and processes. This study explores a potential route in reducing the energy required to create fully hardened PM steel. Specifically, an experiment was designed to determine if changing the initial size of the powder used in the PM steel process changes the sintering kinetics such that more hardenable steel is created. This was accomplished by creating steel of similar chemical compositions comprised of varying powder sizes. A total of 10 samples were tested composed of two chemical compositions and varying particle sizes defined as course (106-149Pm) and fine (less than 45Pm). The hardenability and final mechanical properties were tested via MPIF and ASTM standardized testing as well as SEM, WDS and optical microscopy analyses. The results from these different tests were then compared amongst similar chemical systems. The finer powder was observed to form a more homogenous, dense, and hardenable steel which was ultimately less processable.