Phase Transformation Law of DP1180 Dual Phase Steel for Automobile During Continuous Cooling Transformation

In order to study the phase transformation characteristics of DP1180 dual phase steel for automobile during continuous cooling transformation, metallographic examination and microhardness test were carried out on DP1180 dual phase steel samples under different cooling rates. The continuous cooling transformation curve of the dual phase steel was drawn, and the phase transformation law of DP1180 steel during continuous cooling was analyzed. The results show that the continuous cooling transformation curve of DP1180 dual phase steel for automobile is divided into ferrite transformation zone, bainite transformation zone and martensite transformation zone. Ferrite-bainite transformation mainly occurs when the cooling rate is less than 0. 5 ℃·s^-1. The martensite appears in the microstructure when the cooling rate increases to 1 ℃·s^-1. The ferrite decreases with the increase of cooling rate, and the microstructure becomes martensite and bainite when the cooling rate reaches 10 ℃·s^-1. The microstructure is mainly martensite when the cooling rate is higher than 40 ℃·s^-1.