A study of the influence of strain path change on the microstructure and mechanical properties of low carbon steel using plate and bar rolling

This paper presents an experimental study of the effect of strain path changes with reference to rolling. The fundamental idea considered is to utilize the characteristics of plate rolling and bar rolling. Plate rolling is characterized as monotonic compressive loading while bar rolling is characterized as cross compressive loading. A four-pass plate rolling and bar rolling experiment was designed so that the material experiences the same amount of strain at each pass during rolling. The rolling experiment was carried out at moderately high temperatures (450, 550 and 650°C). The microstructures and mechanical properties of a low carbon steel acquired from two types of rolling experiments were compared. The results revealed that the differences in strain path attributed to monotonic loading (plate rolling) and cross loading (bar rolling) significantly influenced microstructures and mechanical properties.     

整坯轧制在半连轧生产线上的应用

为降低生产成本,增加经济效益,石横特殊钢厂采用自由活套工艺,使轧件在Φ32 0mm×6与Φ2 80mm×6机组之间形成大活套,并通过采取“设计推套器、侧活套台、切尾剪、夹送辊”等技术创新措施,实现了整坯轧制在半连轧生产线上的应用。应用表明:盘条盘重增加2 80kg ,尾部耳子和直条短尺材减少5 0 % ,直条成材率提高0 93% ;轧制间隙时间缩短,年产量增加4万t。     

钛合金棒材三辊螺旋轧制成形数值模拟

利用有限元软件Deform-3D建立钛合金棒材三辊螺旋轧制过程的三维有限元仿真模型,对棒坯轧制从咬入到稳定轧制的全过程进行了模拟分析.研究得出三辊螺旋轧制中棒坯的变形规律,分析了钛合金棒坯成形过程中应力应变情况及轧辊的载荷.该研究对于轧制缺陷控制有着重要的指导意义,为轧机的工艺参数和关键零部件的设计提供了重要依据.     

青钢半连轧棒材生产线切分轧制工艺初探

针对青钢半连轧棒材生产线生产Φ12、Φ14mm带肋钢筋时制约生产力的问题 ,采用了自行设计的切分轧制方案 ,并对轧辊材质、导卫装置型式进行优选 ,使生产效率明显提高 ,合格率达 98 82 %。     

四切分棒材轧制技术在连轧厂的应用

介绍了广州钢铁集团连轧厂引进的四切分棒材轧制技术和主要设备概况;并针对原工艺设备存在的问题,采取了多项措施:如改进料形,精心进行速度调整,严格切分箱装配及安装制度等。改进后年效益在500万元以上。     

棒材轧制轧件出口断面形状预测及平均轧辊半径的新计算模型

对圆—椭圆—圆孔型轧制合金钢,提出了接触边界临界点的概念,建立了出口断面形状预测模型,推导出临界点的解和新的等效接触断面面积公式,给出了计算平均轧辊半径的新模型。为验证新模型,完成了棒材轧制试验,并且利用刚塑性有限元法对轧制过程进行了模拟。将不同模型得到的理论结果与实验值和模拟值作比较,证明新模型具有很高的精度,因此可以用于精轧孔型设计和轧制工艺参数的设定。     

Φ10mm带肋钢筋三切分轧制工艺的控制要点

分析了合肥钢铁集团有限公司连轧棒材厂Φ10mm带肋钢筋三切分轧制工艺的特点及三切分轧制中的控制要点，并针对生产中存在的问题提出了改进措施。     

Analytical model for prediction of deformed shape in three-roll rolling process

In process design of bar rolling, accurate prediction of deformed shape of the rolled workpiece is important in determining the total number of passes. Thus, development of an approximate analytical model for predicting an accurate rolled shape with less computation time will be beneficial for practical purpose. In the present study, such a model for the three-roll system with multi-passes was developed by deriving spread and geometrical configuration formulae from the finite element (FE) analysis results of a seven-passes sequence rolling. In FE simulations, process parameters such as the initial workpiece geometry and the amount of roll draft and roll speed were varied. By comparing spread ratios of FE simulation results three representative geometry changes (round–curved hexagonal, curved hexagonal–hexagonal, and hexagonal–hexagonal) were identified. For each representative geometry change those two formulae were determined in the present investigation. The formulae determined were further applied to a three-roll process with four-passes sequence. The final workpiece geometry predicted based on the model developed was found to be in good agreement with experimental and FE simulation results. Thus, the analytical model developed in the current approach can be effectively used in the design of multi-pass three-roll rolling processes.     

棒材4线切分轧制技术的开发与应用

介绍了水城钢铁公司二轧厂棒材4线切分轧制工艺的开发情况;重点介绍了Φ12mm带肋钢筋孔型系统的选择、导卫系统和活套等的设计及4线切分轧制中的调整操作要点。该技术的开发成功使小时产量提高50%以上,节省能源25%以上。     

高温、中应变速率下预测四道次连续轧制力的流变应力方程(英文)

为了计算在应变速率100～400s-1、温度900～1050℃条件下四道次连续线材轧制过程中的轧制力,提出了一个流变应力方程。基本概念是对Shida模型和Misaka模型进行改进。通常用这2种模型建立的流变应力本构方程来描述高温材料在不同应变率下的变形行为。将改进模型与有限元方法相结合来计算应变速率100～400s-1、温度900～1050℃条件下的四道次连续轧制过程中的轧制力。测量材料在每个道次的轧制力和表面温度,并与预测值进行比较。结果表明,在高温、中应变速率条件下,Misaka模型比Shida模型更好。在900℃时,采用Misaka模型的轧制力误差为-5.7%。在1050℃时,采用Misaka模型的轧制力误差为-15.2%,而采用改进的Misaka模型的轧制力误差降低到1.8%。由此可以得出,对于高温、中应变速率的线材轧制过程,改进的Misaka模型能用来预测高温材料的变形行为。     

马钢全连续式棒材车间工艺设备设计特点

介绍了马鞍山钢铁股份有限公司新建的年产 60万t全连续棒材生产线的工艺特点及设备设计特点。     

Mathematical model to simulate thermo-mechanical controlled processing in rod (or bar) rolling

This study presents a mathematical model for computing the thermo-mechanical parameters such as the strain and strain rate at a given pass and the temperature variation during rolling and cooling between inter-stands (pass), to assess the potential for developing “Thermo-Mechanical Controlled Process” technology in rod (or bar) rolling, which has been a well-known technical terminology in strip (or plate) rolling since the 1970s. The model has then been applied to a four-pass (oval-round or round-oval) bar rolling sequence for predicting the pass-by-pass AGS, by incorporating the equation for recrystallization behavior and AGS evolution being widely used in strip rolling. The predicted AGS was compared with those obtained from the hot torsion experiment. Results revealed the proposed model, coupled with the recrystallization behavior and AGS evolution model developed for strip (or plate) rolling, might be applied directly to rod (or bar) rolling. We also found that the recrystallization behavior during rod rolling was significantly influenced by the method for calculating the thermo-mechanical parameters, especially the strain.     

FEM analysis for hot rolling process of AM60 alloy

The rolling of AM60 sheets for 50%reduction was analyzed with DEFORM to investigate the hot deformation process. The simulated results show that the sheet velocities at the entrance(21 mm/s) and at the exit(37 mm/s) are less and larger than roll velocity,respectively.From the entrance to the neutral point,the velocity at the sheet surface is greater than that at the middle point of sheet in thickness,while that from the neutral point to the exit shows the opposite pattern.The effective strain of the shee...     

高线减定径区带肋钢筋堆钢问题的解决

通过对高速线材生产线在生产带肋钢筋盘条时减定径区堆钢原因的分析，对成品孔型和进、出口导卫进行丁改进，从而使因堆钢而造成的平均事故时间由原来的40min／班减少至5min／班。     

HRB400钢筋在线材轧机上的生产实践

焦作钢铁股份有限公司在复二重线材轧机上进行了Φ6～Φ10mmHRB40 0钢筋的生产 ,通过调整化学成分 ,改造轧线设备 ,并控制冷却工艺 ,生产出了合格钢筋。     

An analysis of accumulated deformation in the Equal Channel Angular Rolling (ECAR) process

Accumulated deformation during a new ECAR process is analyzed. It is found that the effect of the normal strain component is not negligible. The minimum accumulated strain is measured as 0.408 in one-pass ECAR deformed 6063 aluminum alloy sheet. Submicron grain structure is obtained in a 6063 Al alloy sheet by 3-pass ECAR deformation and recrystallization at 250°C for 30 min. This article is based on a presentation made in the symposium “The 7^th KIM-JIM Symposium & the 3^rd International Symposium on nanostructured Materials Technology”, held at KINTEX, Ilsan, Korea, October 27–28, 2005 under auspices of the Korean Institute of Metals and Materials, The Japan Institute of Metals and Center for Nanostructured Materials Materials Technology.     

A study of the effect of the deformation parameters on recrystallization behavior in the rod rolling process

Rod rolling is a process in which the deformation of the workpiece between the work rolls is quite different from the rod drawing process, but the area strains (natural logarithm of area reduction ratio) multiplied by a constant have been used in the calculation of the pass-by-pass evolution of austenite grain size in rod (or bar) rolling without any verification. Considering that the deformation parameters (strain and strain rate) at a given pass play a crucial role in determining recrystallization behavior, the calculation method for the deformation parameters associated with rod rolling should be examined. In this study, a series of numerical simulations has been carried out using an area strain model [5] and an analytic model [6] which calculate the pass-by-pass strain in the rod rolling process, focusing on the effect of the calculation method for the pass-by-pass strain on the recrystallization behavior and evolution of AGS (austenite grain size) during a given pass. These have been investigated for a six-pass rolling sequence (oval-round or round-oval) designed for this study by incorporating the recrystallization and AGS evolution model being widely used in hot rolling. It was found that the recrystallization behavior and evolution of AGS during a given pass were significantly influenced by the calculation methods for deformation parameters. The area strain model lacks mathematical grounds to be used as input to the equations for recrystallization and AGS evolution.     

轧辊参数对铝合金薄板冷轧过程应力应变的影响

铝合金薄板轧制过程中,研究轧辊参数对板材应力应变分布和影响对于确定轧辊参数合理范围、实现冷轧精确成形及预测具有重要意义.本文基于ABAQUS建立了铝合金3A21O薄板带材(30 mm×2 mm,宽度×厚度)冷轧成形三维非线性有限元模型,分析了轧辊直径、轧辊转速对板材应力应变分布的影响.结果发现:(1)压下量为50％时,不同轧辊参数下板材应力分布变化较小,应变分布变化较大,等效塑性应变波动范围为1.68～2.83; (2)改变轧辊参数下,伸长应变分布存在三种形式:“凹”字形、梯形和抛物线形;(3)改变轧辊直径后,厚向应变、伸长应变发生较大变化,局部点处应变相差可达17.9％,增大直径和轧辊转速有利于提高厚度均匀性.     

An experimental investigation on the deformation behavior during wire flat rolling process

In the present study a laboratory flat rolling machine is utilized to assess the deformation behavior of low and high carbon steel wires in wire flat rolling process. The effects of friction coefficient, rolling reduction and roll speed on rolling force and deformation behavior of the wires are experimentally investigated. It is found that the roll speed affects considerably the rolling force but a negligible effect on deformation behavior. It is noted that by increasing the roll speed, the rolling force may decrease or increase depending on the magnitude of the roll speed. Also, the deformation behavior of the wires in flat rolling is formulated. A relationship is developed for calculating the width of contact area between the wire and rolls as a function of rolling reduction. This relationship depicts that the width of contact area is proportional to square root of rolling reduction. Furthermore, two relationships are derived to predict the spreading of the wires after flat rolling. It is found that the relationships are applicable for both the low and high carbon steel wires.     

棒线材多道次轧制过程的静力隐式有限元模拟及模型优化

借助有限元分析软件MSC.Marc,采用三维热机耦合有限元模型和静力隐式算法,对多道次连轧稳态轧制过程进行模拟分析。模型中轧辊间距采用真实尺寸。基于静力隐式算法的特性,在优化模型中引入刚性推动体,实现模型的简化。比较优化前后两种有限元模型的模拟结果及参数,表明该文所建立的优化模型可以在保证较好的计算精度前提下,显著地提高运算效率。应用优化模型模拟粗轧六道次连轧过程,温度变化模拟结果与实际测量结果吻合较好。