Study on Precipitation Hardening of C 250 Grade Maraging Steel

The present work reports effect of different heat treatment processes on the microstructure and hardness of C 250 grade maraging steel. Different heat treatment processes have been carried out and the resultant microstructure and hardeness have been characterized. Various structural characterization techniques, such as, optical microscopy, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, etc. have been adopted and the microstructural features thus evaluated have been correlated with the mechanical property, viz. hardness. Presence of Ni-3(Ti,Mo) particles in lath martensitic matrix are revealed in solution treated and aged alloy. It is found that conventional maraging treatment consisting of solution treatment at 850 degrees C, followed by forced air cooling and finally ageing at 500 degrees C gives the best hardening response. Grain refinement techniques are not much effective for the improvement of hardness of maraging steel in the age hardened condition.