冷却工艺对热轧高强带钢残余应力的影响

Effect of cooling process on reducing residual stress of hot rolled high strength strip

为分析不同层流冷却工艺对热轧高强带钢残余应力的影响规律,以ABAQUS有限元软件为基础,采用FORTRAN语言编写用户子程序,建立热轧高强带钢快速冷却过程的有限元模型,对带钢层流冷却过程中温度场、组织及应力场的演变规律进行耦合计算。针对现场工艺,设计并实施过冷奥氏体连续冷却转变(CCT)试验和残余应力测试等试验对模型进行校正。以校正后的模型作为基础模型,修改基础模型的初始条件和边界条件,建立与边部遮挡、稀疏冷却、后段冷却、降低初始温差等4种层流冷却工艺对应的有限元模型,以定量分析4种工艺对减小带钢残余应力的效果。研究结果表明:原来无应力的带钢,经过层流冷却后,带钢宽度方向的应力分布变为边部有较大的压应力,中部有较小的拉应力。4种工艺都能有效减小残余应力,降幅从高到低依次为降低带钢横向初始温差、稀疏冷却、边部遮挡、后段冷却。

In order to analyze the influence of different laminar cooling technology on residual stress of steel strip, a finite element model of strip was established with ABAQUS and FORTRAN named basic model. Multiple experiments were carried out to verify the accuracy of the basic model such as continuous cooling transformation（CCT） test of super cooled austenite and residual stress measurement. The evolution of temperature, phase transformation and stress of the strip during cooling process were expressed with coupling calculation. Other four finite element models were established based on the basic model by changing its initial condition and boundary condition. The new models represented four cooling technology named edge masking, sparse cooling, posterior cooling, and initial transverse temperature difference controlling. The results show that the stress distribution on strips tends to be high compressive stress on edge and tensile stress on middle section. The effect of the four cooling technologies on the residual stress reduction is ranked as initial transverse temperature difference controlling, sparse cooling, edge masking and posterior cooling.