厚板厚向温度分布对热轧过程金属变形的影响

基于温控形变耦合工艺下轧件厚向温度分布的特点,即使轧件厚向芯表温差相等,但厚向温度梯度不同,会对金属变形产生不同的影响。通过数值模拟,研究了厚板厚向温度梯度对轧件内部金属变形的影响。对于芯表温差为300 ℃的温度场,随着冷却强度与水冷时间的不同,沿钢板厚向会形成“近表层大温度梯度区+近芯部等温区”的混合温度场。随着冷却强度的增大,水冷时间的减少,近芯部等温区厚度逐渐增加。经模拟计算,当钢板近芯部等温区厚度增加至1/2板厚时,轧件芯部应变值减少约0.015。结果表明,大冷却强度、少水冷时间的温控形变耦合工艺,会弱化轧件厚向变形渗透效果。另外,随着近芯部等温区厚度的增加,头部沿纵向金属变形不均匀性减小,表明大冷却强度、少水冷时间的温控形变耦合工艺,有利于提高轧件头部沿长度方向的金属流动均匀性。

Effect of temperature distribution along plate thickness on the metal deformation during hot rolling

According to thickness direction temperature distribution characteristics of rolled piece based on rolling with inter-pass cooling process,even if the temperature difference between heart and surface of rolled piece is equal,different temperature gradient in thickness direction will have different influence on metal deformation.The effect of thickness temperature gradient on the metal deformation in plate was studied by simulation.For the temperature field with a heart-surface temperature difference of 300 ℃,according to the different cooling capacity and cooling time,the "near surface temperature gradient field and near heart isothermal temperature field" would be formed in the thickness direction of the plate.The near heart isothermal field thickness increases with the increasement of water cooling capacity and reduction of cooling time.Through simulation,when the near heart isothermal field thickness of plate increases from 0 mm to half thickness of plate,the strain at the plate heart decreases by about 0.015.The results show that high water cooling capacity and low cooling time will weaken the permeability of deformation.In addition,with the increasement of the near heart isothermal field thickness,the plate head metal flow inhomogeneity along the longitudinal direction will decrease.It indicates that high water cooling capacity and low cooling time will improve the deformation uniformity of the head along length.