Measurement and analysis of CCT curves of ship plate steel

Simulated experiment was carried out on a ship plate steel by means of Gleeble3500 hot simulation experiment machine, and the volume expansion data vs temperature were collected. Combined with the metallographic analysis and hardness test, the CCT curves of the ship plate steel were obtained. According to the CCT curves and the microstructures under different cooling rates, the phase transformation of the ship plate steel under different cooling rates was determined. With the increase of cooling rate, the microstructure of the steel is varied from the polygonal ferrite, quasi polygonal ferrite gradually to granular bainite and bainite ferrite transformation. And the microhardness is obviously increased with the cooling rate.