Quenching and Partitioning (Q & P), an innovative heat treatment process was developed by J. G. Speer in 2003 to produce third generation high strength steels with improved toughness for making chassis of high speed cars. The Q & P process was applied to the low alloy AISI-4340 steel for different partitioning time periods. The characterization process encompassed microscopic study through optical microscope and hardness testing by micro Vickers hardness tester. Also, corrosion behaviour of different samples, partitioned at various time periods was studied by Gamry Potentiostat. Light optical microscopy revealed that microstructure consists of lath martensite and inter lath blocky retained austenite. The volume fraction of the retained austenite showed an initial progressive increase in proportion with the partitioning time but later pursued   a decrease at partitioning time of 60 and 120 sec, steadily. The hardness values were increased from 236 HV for a non-heat treated sample to 477 HV for 15 sec partitioned sample thereafter decreased with increase in partitioning time. The electrochemical test results showed a continued mitigation in the corrosion rate from 3.581 mpy for non-heat treated sample to 0.08 mpy for the 30 sec partitioned steel sample.