平整加工对高强钢抗畸变能力的影响及优化

为解决高强带钢在生产加工过程中产生的板形缺陷和畸变，本文采用裂纹柔度法测量单下辊传动平整加工前后620JJ带钢内部残余应力，并依据残余应力在厚度或板宽方向分布不均将导致带钢发生畸变，定义带钢应力不平衡度为畸变评价指标，分析了平整工艺对带钢内部残余应力分布和畸变的影响，并利用ABAQUS有限元模拟探究了工艺优化方案。结果表明：裂纹柔度法能够准确表征带钢内部残余应力；应力不平衡度可以直观地表征带钢产生畸变的可能性；平整加工对带钢的主要影响是应力的均衡化和降低整体残余应力水平，平整前后各测点弹性应变能极值与平均值差值从169.25 MPa·mm降至141.86 MPa·mm,带钢内部残余应力的最大值由463.26 MPa降至363.6 MPa;将平整工艺改为双辊传动、增加摩擦力、增加张力、增加轧制力等方式均可有效改善应力不平衡度。

Effect and optimization of flattening process on anti-distortion ability of high-strength steel

In view of the shape defects and distortion of high-strength strip steel during production and processing, the crack compliance method was adopted to measure the internal residual stress of 620JJ strip steel before and after flattening process with single bottom roller drive.Since the uneven distribution of residual stress on the directions of thickness or plate width led to the distortion of the strip,the stress unbalance of the strip was defined as distortion evaluation index.The influence of the flattening process on the residual stress distribution and distortion inside the strip was analyzed, and the ABAQUS finite element simulation was used to explore the process optimization scheme. Results show that the crack compliance method could accurately characterize the residual stress inside the strip.The degree of stress unbalance could intuitively characterize the possibility of strip distortion.The main effects of flattening on the strip were the equalization of the stress and the reduction of the overall residual stress.The difference between the extreme value and the average value of elastic strain energy at each measuring point before and after flattening reduced from 169.25 MPa·mm to 141.86 MPa·mm, and the maximum value of residual stress inside the strip reduced from 463.26 MPa to 363.6 MPa.The flattening process was optimized by using two-roller transmission and increasing friction, tension, and rolling force respectively,and the stress unbalance could be effectively improved.