Effect of silicon, vanadium and nickel on microstructure of liquid phase sintered M3/2 grade high speed steel

Liquid phase sintering of M3/2 grade high speed steel (HSS) was carried out at 1270 degrees C in high vacuum reaching near full density starting from loose packed powder. Focus is placed oil the study of the effects of the addition of Si. Ni and V as elemental powder and cooling rates oil the as sintered microstructure, the main objective being improving M6C characteristics and control of pearlite appearance. Slow cooling from the sintering temperature and Si addition in wt% resulted in a completely fine pearlitic matrix with less elongated and more uniformly distributed M6C precipitates. Adding V or Ni in wt-% quantities decreased the amount of pearlite owing to MC formation and delayed pearlite formation. The study involved the use of thermodynamic modelling and sintering cycle optimisation as well as the evaluation of sintered material by means of optical and scanning electron microscopy, X-ray diffraction and hardness testing.