780 MPa级冷轧塑性诱导相变钢研究

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

塑性诱导相变钢(TRIP钢)微观组织由铁素体、马氏体和残余奥氏体组成的具有较高强度和良好塑性的优质钢板。为了研究连续冷却条件下过冷奥氏体的转变规律,测定了试验钢的连续冷却转变曲线(CCT曲线),研究了冷却速度对显微组织和硬度的影响。结果表明,相变区域包括A→P转变区、A→B转变区和A→M转变区。当冷却速度提高到2℃/s时,不仅出现A→P转变,而且伴随有A→B转变。当冷却速度提高到3℃/s,仅有A→B转变。当冷却速度提高到10℃/s,出现A→M转变。根据实验室研究结果,进行了工业试制,成品态的屈服强度、抗拉强度、伸长率A_(50)和n值分别为535 MPa、815 MPa、29.5%和0.25,力学性能满足TRIP780要求。

The microstructure of transformation induced plasticity steel （TRIP） is composed by martensite and retained austenite, and have high qualified steel plate with high strength and good ferrite, plasticity. 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 microstructure 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. steel, CCT curve, microstrueture, phase transformation, hardness