Influence of delubrication process on the properties of sintered PM components

Paper in proceeding, 2013

Problems associated with improper delubrication are frequently encountered during the manufacturing of sintered components but are very difficult to identify in a continuous sintering process. The effect of delubrication parameters on the final properties of chromium prealloyed PM steels has been studied by varying the delubrication processing conditions (thermo-profile and processing atmosphere) followed by sintering in Ar/10%H2 mixture at 1120 ºC. The best results after sintering were obtained for the compacts delubricated at 450 °C in dry nitrogen. Increasing the delubrication temperature to 900 °C resulted in slightly higher impact energy and as-sintered oxygen content but high carbon loss and lower hardness. Delubrication in air resulted in high carbon losses and the lowest impact energy and hardness values. These effects were related to considerable surface oxide changes during delubrication detected by HR SEM+EDX analyses. Delubrication at 300 °C was insufficient resulting in soot formation and inferior as-sintered mechanical properties.