Wang Guo-dong

A three-dimensional finite element simulation of the vertical–horizontal rolling process in the width reduction of slab

Abstract A thermal coupling analysis is carried out by the full three-dimensional rigid–plastic finite element method to simulate vertical–horizontal rolling process during width reduction in the roughing stands of a hot strip mill. The slab shape, the spread and temperature as calculated are in good agreement with the experimental results in production mills, and the sectional distribution of temperature is given.

3-D rigid–plastic FEM analysis of the rolling of a strip with local residual deformation

Abstract A strip with longitudinal ribs is one type of new-shaped strip that has been developed in recent years. The main characteristic of the rolling of a strip with ribs is that there is local residual deformation on a normal flat, and it is a new forming process that has the deformation characteristics of both strip- and shaped-steel. Using the rigid–plastic FEM, the forming process is analyzed in this paper and the numerical results of the change of the rib height in the deformation zone and of quantities such as rib height, the separating rolling load and the spread ratio have been obtained, the result of calculation being in accordance with those of the experiment.

Three-dimensional thermo-mechanical finite element simulation of the vertical–horizontal rolling process

Abstract This paper presents a three-dimensional thermo-mechanical analysis of the vertical–horizontal rolling process utilised in the large width reductions of slabs in hot strip mills. The theoretical analysis is based on the utilisation of the finite element flow formulation to characterise the material flow, to predict the distribution of temperature and to estimate the roll separating force. The numerical predictions were verified by metal experiments performed at the hot strip mill unit of Bao Steels (China). The experimental work consisted of the monitorisation of the surface temperature and of the roll separating force for several rolled slabs. The theoretical distribution of stress obtained from the numerical simulation of the process is also analysed.

Self-Learning and Its Application to Laminar Cooling Model of Hot Rolled Strip

The mathematical model for online controlling hot rolled steel cooling on run-out table (ROT for abbreviation) was analyzed, and water cooling is found to be the main cooling mode for hot rolled steel. The calculation of the drop in strip temperature by both water cooling and air cooling is summed up to obtain the change of heat transfer coefficient. It is found that the learning coefficient of heat transfer coefficient is the kernel coefficient of coiler temperature control (CTC) model tuning. To decrease the deviation between the calculated steel temperature and the measured one at coiler entrance, a laminar cooling control self-learning strategy is used. Using the data acquired in the field, the results of the self-learning model used in the field were analyzed. The analyzed results show that the selflearning function is effective.

Analysis of the non-steady state vertical–horizontal rolling process in roughing trains by the three-dimensional finite element method

Abstract The vertical–horizontal rolling process is often used to accomplish width reduction so as to provide a synchronising operation between the continuous slab casting and hot rolling processes. Numerical simulation of the non-steady state deformation behaviour around the head and tail ends during this process is made by the full three-dimensional rigid–plastic finite element method. An explanation is provided in the theory for the ‘thin element technique’ at the inlet surface of velocity discontinuity. To deal with the interpolation of friction within a surface of an element contacting partly with the roll, a new term, so-called ‘pseudo shape function’, is presented and a related new equation formula is deduced. The calculated shape of the slab edge, the separating force and the rolling torque are consistent with those measured experimental ones for the model material lead.

Shifting-roll profile and control characteristics

Abstract CVC (continuously variable crown) technology is a new method for controlling strip shape and profile. The key to developing this technology is the principle for designing the CVC roll profile. This paper analyzes this point in depth, and points out that the conventional CVC roll profile is composed of a cubic curve. With the aid of experimental research, it is confirmed that this type of CVC roll is effective for controlling the center buckle and edge buckle. Furthermore, a new type of CVC roll profile with a quintic curve is designed. Theoretical study has been made, which shows that the newly designed CVC roll is effective for controlling quarter buckle.

Application of synergetic artificial intelligence to the scheduling in the finishing train of hot strip mills

Abstract In Synergetic Artificial Intelligence, Fuzzy Theory and Expert System can simulate logical inference ability in left-half-brain of human being. Theory models and Artificial Neural Networks can simulate thinking of images in right-half-brain of human being. All these parts of the methods fuse each other. It can settle many problems that can not be solved by traditional methods. In paper, Synergetic Artificial Intelligence is introduced and is applied to scheduling in finishing train of hot strip mills.

PRECIPITATION BEHAVIOR OF CARBIDE DURING HEATING PROCESS IN Nb AND Nb-Mo MICRO-ALLOYED STEELS

As an important carbide forming element, Nb plays an important role in steel. Precipitated Nb can restrain the austenite grain growth during soaking process and provide precipitation strengthening after g /a phase transformation. Precipitated or dissolved Nb can inhibit recrystallizaton of deformed austenite. Recently, both Nb and Mo are added in steel to enhance the role of Nb. However, these kinds of researches mostly focused on continual cooling process of g /a transformation or isothermal process during tempering, and precipitation behavior of MCtype carbide in steel containing Nb and Mo during reheating process and the effect of Mo on precipitation of Nb C in ferrite were rarely reported. Therefore, in this work, precipitation behaviors of MC-type carbide and the synergis-tic effect of Nb and Mo in steel containing Nb or Nb-Mo during reheating process at the heat rate 20 ℃/min were investigated by means of Vickers hardness test, SEM, HRTEM and DSC. The results show that both Nb and NbMo steels have hardness peaks at 300 and 700 ℃, which are attributed to the precipitation of e-carbide and MCtype carbide, respectively. The MC-type carbide precipitates at about 650 ℃ during reheating process, which is in a good agreement with the nose temperature of MC-type carbide calculated by Avrami equation.(Nb, Mo)C particle forming in Nb-Mo steel during precipitation has a small mismatch with ferrite matrix compared with Nb C, leading to the decrease of interfacial energy. Thus, the precipitation kinetic of MC-type carbide in Nb-Mo steel is faster than that in Nb steel, which results in the denser and finer MC-type carbide and higher precipitation strengthening effect.

Forward and Backward Slip Models in MAS Rolling Process and Its On-Line Application

Based on the MAS rolling process in plate mill, the mathematical models of forward and backward slips of the wedges at plate head and tail were derived. According to the new model, the difference between the forward slip of the wedge and that of the normal part of the plate is obviously very small. The deviation is less than 2. 5% in general. Thus, in actual application, the forward slip of normal part of the plate can be used to calculate the length of rolled plate instead of the derived model. The rationality of this simplified method was confirmed with the application in Shougang 3 500 mm plate mill. The test results showed that the wedges of plate head and tail are symmetrical. The plate width deviation is greatly decreased by using the MAS method.

Derivation of Simplified Models of Plan View Pattern Control Function for Plate Mill

The plan view pattern control theoretical models were simplified. Under the condition of constant volume for the plan view pattern compensation, the relation between the thickness and the length can be simplified to the linearity in the segment for the plan view pattern control function. The compensation volume can be dispersed for easy calculation. By comparing the model calculation result with the actual result, it was concluded that the simplified model can be used for the online control process.