含磷高强IF钢拉矫断带的原因及机制

Research on the Factors Inducing Strip Fracture of High Strength IF Steel Containing Phosphorus During Straightening Process

采用场发射SEM及TEM研究了含磷高强IF钢拉矫断带的断口形貌及析出物的分布状态,结果表明导致断带的主要原因是晶界处大尺寸、树枝状Fe(Nb,Ti)P相的偏聚析出。通过对断带样品的热处理回溶试验及不同层冷冷速的热模拟试验,分析了造成Fe(Nb,Ti)P相晶界富集析出的温度范围及工艺要素。在机制研究的基础上,制定了热轧生产的控制要点,主要包括轧制温度、层冷冷速、成分设计、卷取温度等多个方面,成功抑制了高P类高强IF钢的拉矫断带事故发生率。

Based on the morphology observation of fracture and precipitate of high strength IF steel containing phosphorus with SEM and TEM, the segregation of coarse dendritic Fe（ Nb, Ti）P at the grain boundaries was concluded as the mainly reason inducing the strip fracture during straightening process. Through the precipitate dissolving experiments upon the fracture strip and the thermal simulation experiments simulating different lami nar cooling speed, the precipitation temperature range and factors causing Fe（ Nb, Ti）P segregation at the grain boundaries was revealed. On the basis of the theoretical research, several effective methods are proposed to reduce the occurrence of strip fracture including the optimization of rolling temperature, cooling speed of laminar cooling, composition design, and coiling temperature etc, which has succeeded in restraining the strip fracture during straightening process.