Study on the Transformation Induced Plasticity Steel of 780 MPa Grade Cold Rolled

The microstructure of transformation induced plasticity steel(TRIP) is composed by ferrite,martensite and retained austenite, and have high qualified steel plate with high strength and good plastici-ty.To study super-cooled austenite transformation under the condition of continuous cooling,the determi-nation of continuous cooling transformation curve had been done, and the influence of cooling rate on mi-crostructure and hardness had been investigated.The results showed that the phase transition area included A to P transition zone, and A to B transition zone and A to M transition zone.When the cooling rate was increased to 2℃/s,both A to P transformation and A to B transformation occurred.When the cooling rate was increased to 3℃/s,only A to B transformation took place.When the cooling rate was increased to 10℃/s,A to M transformation occurred.Based on the experimental results,the industrial production have been done and achieved satisfied TRIP 780 strip where the yield strength,tensile strength and elongation A₅₀ and n value were 535 MPa,815 MPa,29.5% and 0.25,respectively.