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针对卷取温度为500℃的12 mm厚X70管线钢热轧带钢,利用MARC有限元软件建立层流冷却过程中的热-力-相变耦合的数学模型,计算两种下上冷却水比时层流冷却过程中温度场、应力、应变、相变体积分数和翘曲度随时间的变化.结果表明:1.25水比的冷却过程中,厚度方向上各面的冷却速度不一致,导致水冷前期带钢上下表面应变不同,带钢会产生向上的翘曲,冷却过程中边部最大的翘曲量达到21.84 mm;水冷后期带钢板形会逐渐恢复平直,但由于水冷过程中发生塑性变形,终冷时厚度方向上贝氏体含量的差异,卷取时带钢边部依然有-9 mm的翘曲量.上下表面的不均匀冷却是引起翘曲的根本原因.在保证X70管线钢性能条件下,采用1.58的下上水比工艺,卷取时边部翘曲量仅为-0.58 mm,合适的下上水比能大幅度减小层流冷却过程中带钢的横向翘曲.
Aiming at the hot-rolled 12 mm thick X70 pipeline hot-rolled steel strip with a coiling temperature of 500 ℃, a mathematical model of thermo-mechanical-mechanical coupling during the laminar cooling was established by MARC finite element software. Temperature, stress, strain, volume fraction of phase change and warpage over time during laminar cooling were studied.The results show that the cooling rate of each side in the thickness direction is not the same during the cooling process of 1.25 water ratio, The upper and lower surface of the strip with different strain, the strip will produce upward warp, the maximum warping of the edge of the cooling process reaches 21.84 mm; late strip shape water cooling will gradually restore straight, but due to plastic deformation during water cooling, The difference of bainite in the thickness direction at the time of final cooling, the amount of warpage at the edge of the strip remained at the time of coiling was -9 mm.The uneven cooling on the upper and lower surfaces was the root cause of warpage.When the performance of X70 pipeline steel Under the conditions of 1.58 under the water ratio of the process, the amount of warping when the edge of the curl is only -0.58 mm, the appropriate ratio of water under the Sheung Shui can significantly reduce the laminar flow in the process of cooling the lateral warpage.