Supersolidus liquid phase sintering of injection molded M2 tool steel

Supersolidus liquid phase sintering was used to process powder injection molded low and high carbon grade M2 tool steel, formed with a polyacetal based binder and subjected to catalytic debinding, This is a technique whereby a prealloyed powder compact is heated above the solidus temperature to form internal liquid which densifies the compact rapidly, Full density processing was possible without significant distortion in thick sections, Carbon control was achieved through temperature and atmosphere control in debinding and sintering. Debinding and sintering cycles were generated through dilatometry, sintering experiments, carbon analysis, and metallography, After catalytic removal of the polyacetal binder, samples were debound in a 50v/o H-2/50v/o N-2 atmosphere in a retort furnace heated at 5 degrees C/min to 600 degrees C for 1 h, then heated at 10 degrees C/min to 850 degrees C for 30 min. Samples were sintered in 15v/p H-2/85v/o N-2 in a batch furnace heated at 10 degrees C/min to the sintering temperature for 30 min. The sintering temperature window which produced full density with well dispersed carbides was determined to be 1275 to 1287 degrees C for 30 min, A high carbon grade which (1w/o) was processed for comparison to the low carbon grade (0.83w/o) showed similar densification behavior, at approximately 25 degrees C lower temperatures.