热轧大H型钢组织预测及工艺设计

发布时间：2018-04-21 16:46

本文选题：H型钢 + 热轧　；参考：《北京科技大学》2015年博士论文

【摘要】：H型钢具有众多优点,在建筑、造船、机械制造等众多领域均有广泛的应用,是国家鼓励使用的节能环保型“绿色钢材”。H型钢复杂多样的使用环境对H型钢的组织和性能提出了新的、更高的要求。为了经济、便捷地生产合格的产品,基于现有的研究成果,面向组织的生产工艺设计方法被建立起来。本文以Q235B钢种HN800×300H型钢作为研究对象,结合山东莱芜钢铁集团公司大型H型钢生产线的实际工艺,采集了轧制力、温度等生产实测数据,对H型钢开坯前、精轧后和空冷后产品的组织进行了金相观察与分析,并通过热模拟实验建立了Q235B钢的高温流变应力模型。在此基础上,基于ABAQUS软件建立了H型钢全轧程组织预测仿真模型,分析了轧制力、温度场、组织场等仿真结果,验证了仿真模型的准确性,为H型钢工艺设计研究提供了数据支撑。在分析结果的基础上,基于Hodgson组织预测模型,采用灵敏度分析方法提出了面向组织的正向工艺设计及优化方法,便捷、有效地解决了轧制过程晶粒细化的问题；采用逆向设计方法提出了面向组织的逆向工艺设计方法,有效地解决了生产指定晶粒尺寸轧钢产品的问题。本文的主要工作及结论如下： (1)采用单道次压缩实验数据,构建了考虑再结晶信息的新型高温流变应力函数,准确描述了Q235B钢的高温变形行为。同时,基于ABAQUS用户子程序VUMAT和UMAT构建了适用于显式轧制过程计算和适用于隐式间隙过程计算的材料模型,成功地将高温流变应力函数模型和弹塑性增量本构关系引入了仿真模型中。 (2)分析总结了现有的经典再结晶模型,并采用单道次压缩实验和双道次压缩实验数据分析验证组织演化模型的准确性、适用性,证明Hodgson模型是较为准确的、适用的。分析Hodgson模型得出了模型包含的固有缺陷,并提出了相应的解决办法,保证了仿真计算结果的准确性、合理性。同时,基于ABAQUS用户子程序VUMAT和UMAT成功引入组织演化模型,实现了H型钢轧制过程组织预测仿真计算。 (3)结合材料模型和组织预测模型,根据轧制规程构建了HN800x300H型钢轧制过程组织预测仿真模型,并采用网格重构和数据传递等方法实现了全轧程组织预测计算。轧制力结果分析表明,开坯过程轧制力仿真值与实测值相对误差在1.60%-28.63%之间。组织预测结果分析表明,奥氏体晶粒尺寸在轧制过程减小,间隙过程长大,且腹板奥氏体晶粒尺寸在精轧过程变化不大,而翼缘和R角在精轧过程反复减小和增大；R角晶粒尺寸最大、翼缘次之,腹板最小,分布规律与金相观察结果一致。 (4)采用灵敏度分析方法,结合优化算法实现了H800×300H型钢开坯轧制工艺的正向设计。基于灵敏度定义,结合Hodgson再结晶模型建立了单道次、多道次过程奥氏体晶粒尺寸对工艺参数的灵敏度方程,并采用该方程分析得出温度、第6道次应变速率和间隙时间、第7道次应变和和间隙时间对开坯后奥氏体晶粒尺寸影响最大的结论,进而设计了新工艺,使得开坯后奥氏体晶粒尺寸约为43.10μm,较原工艺所得奥氏体晶粒尺寸值减小38.34%。 (5)基于Hodgson再结晶模型,建立了逆向工艺设计方法,并将其应用于H800×300H型钢开坯轧制的工艺设计,实现了面向组织的轧制工艺设计。在假设已知温度和变形量变化范围的基础上,建立了不同组织演化路径下应变速率、间隙时间和初始晶粒尺寸的可行域的数学模型；同时以工艺距离为度量,提出了工艺参数选择的依据,解决了工艺路径存在多条的问题,并保证了工艺路径的有效性。采用逆向工艺设计方法所得的H型钢开坯轧制新工艺通过适当降低轧制温度、缩短间隙时间、调整应变量大小实现了设计目标,开坯轧制后奥氏体晶粒尺寸达到预期的50μm,证明了逆向工艺设计方法的准确性、有效性。
[Abstract]:H steel has many advantages. It is widely used in many fields, such as building, shipbuilding, mechanical manufacturing and so on. It is an energy saving and environment-friendly "green steel" type.H steel which is encouraged by the state to use the complex and diverse environment to put forward new and higher requirements for the organization and performance of H type steel. Some research results have been established for organization oriented production process planning.
In this paper, the Q235B steel HN800 x 300H steel is taken as the research object. Combined with the actual process of the large H steel production line of Shandong Laiwu iron and Steel Group Corporation, the measured data of rolling force and temperature are collected. The microstructure of the product is observed and analyzed after the finish rolling of H steel, after the finishing rolling and after the air cooling, and Q2 is established by the thermal simulation experiment. The high temperature rheological stress model of 35B steel is based on this, based on the ABAQUS software, the simulation model of the whole rolling process of H steel is established, and the simulation results of rolling force, temperature field and tissue field are analyzed. The accuracy of the simulation model is verified, and the data support for the study of H steel process design is provided. Based on the analysis results, Hodgson is based on the Hodgson. An organization oriented forward process design and optimization method is proposed by the method of sensitivity analysis, which is convenient and effective to solve the problem of grain refinement in the rolling process, and a reverse design method of reverse design is put forward by reverse design method, which effectively solves the problem of producing steel rolling products with specified grain size. The main work and conclusions of this article are as follows:
(1) a new high temperature rheological stress function, which considers the recrystallization information, is constructed to describe the high temperature deformation behavior of Q235B steel accurately. At the same time, the material model, based on the ABAQUS user subroutine VUMAT and UMAT, is constructed to calculate the explicit rolling process and apply to the calculation of the implicit clearance process. The high temperature flow stress function model and elastoplastic incremental constitutive relation are introduced into the simulation model.
(2) analyzing and summarizing the existing classic recrystallization models, and using single channel compression experiment and double channel compression test data analysis to verify the accuracy and applicability of the organization evolution model, and prove that the Hodgson model is more accurate and applicable. The analysis of Hodgson model gives the inherent defects of the model type, and puts forward the corresponding solutions. It ensures the accuracy and rationality of the simulation results. At the same time, based on the ABAQUS user subroutine VUMAT and UMAT, the organization evolution model is successfully introduced, and the simulation calculation of the microstructure prediction of the H steel rolling process is realized.
(3) combining the material model and the organization prediction model, the simulation model of the microstructure prediction of HN800x300H steel rolling process is constructed according to the rolling regulation. The whole rolling process prediction calculation is realized by means of grid reconstruction and data transfer. The analysis of rolling force results shows that the relative error between the simulation value of rolling force and the measured value is 1.60%-28. 63%. The analysis of the microstructure prediction results shows that the austenite grain size decreases in the rolling process, the gap process grows, and the austenite grain size of the web has little change in the finishing process, while the flange and R angle decrease and increase repeatedly in the finishing process; the R angle grain size is the largest, the flange is the second, the web is the smallest, the distribution law and the metallographic observation result. Agreement.
(4) using the sensitivity analysis method and combining with the optimization algorithm, the forward design of H800 x 300H steel rolling process is realized. Based on the sensitivity definition and the Hodgson recrystallization model, the sensitivity formula of the austenite grain size to the process parameters is established, and the temperature is obtained by the equation analysis, and the sixth pass should be obtained. The influence of the speed and clearance time, the seventh pass strain and the interval time on the grain size of the austenite after opening is the most important, and a new process is designed, which makes the grain size of austenite after opening is about 43.10 m, and the austenite grain size value of the original process decreases by 38.34%..
(5) based on the Hodgson recrystallization model, a reverse process design method is established and applied to the process design of H800 x 300H steel rolling. The organization oriented rolling process design is realized. On the basis of the change range of the known temperature and deformation, the strain rate, clearance time and initial stage under the different evolution path are established. A mathematical model of the feasible region of the grain size; at the same time, the basis of the process parameter selection is put forward with the technological distance as the measure. The problem of multi strip in the process path is solved, and the effectiveness of the process path is guaranteed. The new process of rolling H steel rolling through the reverse process design method can reduce the rolling temperature and shorten the interval through the proper reduction of the rolling temperature. The design goal was achieved by the time of clearance and the adjustment of the size of the strain. The grain size of austenite reached the expected 50 m after rolling, which proved the accuracy and effectiveness of the reverse process design method.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG335.11

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