X65厚管线板控冷工艺与翘曲分析

The Study of Controlled Cooling Technology and Warping of X65 Heavy Pipeline Plate

通过扩展Avrami相变动力学模型、开发线性混合热膨胀模型和使用Leblond相变诱导塑性(TRIP)模型建立了X65厚管线板控冷过程的热力耦合有限元模型,全面考虑了相变潜热、相变膨胀、TRIP效应、热膨胀等机制.用该模型对3种控冷模式下X65厚管线板控冷过程的温度场和应力/应变场进行了模拟,并分析了控冷模式对翘曲变形的影响.结果表明:不对称冷却产生的上下表面间的温差所导致的应力/应变场的不对称分布是材料翘曲的根本原因;交替冷却不仅可降低温差,还可大幅减小材料的翘曲;实现上下表面对称冷却和采用交替冷却是保证产品平直和性能均匀的有效方法.

A thermo-mechanical coupled finite element model is established, which combines the modified Avrami transformation dynamics model, the linear mixture thermal expansion model, and the Leblond transformation induced plasticity （TRIP）model. The model considers latent heat, transformation dilatation, TRIP effect, as well as thermal expansion and elasto plastic deformation. The influence of three different controlled cooling modes on temperature field and stress, strain field of X65 heavy pipeline plate is simulated and the warping of plate is analyzed. The result shows that the main reason of warping is the temperature difference between the top and bottom surfaces from unsymmetric cooling, which causes the unsymmetric distribution of stress and strain field. Alternate cooling, in which laminar cooling and air cooling appear alternately, decreases the temperature difference and reduces the magnitude of warping strongly. To avoid warping and to realize the uniformity of properties, it is more effective to maintain the cooling homogeneity between the top and bottom surface of plate during controlled cooling, and to use alternate cooling.