科创中国

The stainless steel microstructure evolution of carbon–stainless-clad steel plate was investigated during vacuum hot-rolling bonding under different deformation conditions. The results show that carbide M2C precipitates in the interior of stainless steel (SS) and carbon content increases with rising reduction ratio (ε). The dislocation density of the SS surface (ρI) is lower than that of the midst (ρM),and ρI decreases with the rising ε. However,ρM increases first and then decreases with rising ε. The dislocation density of bonding interface decreases due to the increasing size of austenite grain. Furthermore,the dislocation density of the midst is high where the high energy of carbide M₂C is concentrated for single-pass rolling,and the quantity of M2C increases with reduction ratio. Moreover,carbide almost disappeared while being transformed into austenite,and only minimal granular carbides were formed after two-pass rolling. Bonding strength increases evidently with rising ε and is inversely proportional to ρI.

Hai Bin Li;庆学 黄;Cun Long Zhou;Guang Ming Liu;Qin Ma

Medziagotyra

2016

A Boundary Element Method (BEM) is used to study the roller bearing contact problem due to its high non-linearity. The plate units are used to simulate the rollers, the bearing boundary elements are used to realize the discontinuous nature of the traction on the contact area, and the Hertz contact theory is used to revise contact widths between rollers and the inner and outer races. According to assembly and fit characteristics of rolling mill tapered roller bearings, in which both clearance fits are adopted to the inner race with the mill roll and the outer race with the shaft block, the four-objects elastic frictional contact program of bearing BEM is compiled, with which a rolling mill four-row tapered roller bearing is simulated. The shaft block direct measure method is used to measure the load distribution of the four-row tapered roller bearing. The experimental data and the result of simulation are compared, and the load distribution laws of simulation identify with the test result, which proves the validity and effectiveness of using elastic frictional contact BEM to analyze the load distribution of bearing.

Xia Yang;庆学 黄;Chuang Yan

Engineering Analysis with Boundary Elements

2015-7

Sectional rolling-mill housing of wide heavy plate mill can achieve the comparative mechanical properties as one-piece housing by preload. Research on the optimal preload can effectively decrease the deformation of the window, thus reducing the extrusion damage of the roll bearing seat. The size of the 5 000 mm sectional rough rolling-mill housing of Yingkow was measured. Based on the finite element theory, the ANSYS WORKBENCH software was used to conduct the static structural analysis of the sectional rolling-mill housing without preload. After selecting the bolt preload as the design variables and setting the objectives, the preload of the bolts was optimized by multi-objective optimization method based on the multi objective genetic algorithms. The optimal preload could ensure the mill housing with enough strength, no gap between the beam and column as well as the smallest window deformation. Both the strength and stiffness of the housing were optimized. By comparing the pressure experiments obtained stiffness value with the simulation results, it is found that the error was 5.5%, which effectively verifies the reliability of finite element simulation.

Li Jiang;庆学 黄;Lin Zhu;Xiao Min Zhang;Jiang Zhang;Pu Li

Suxing Gongcheng Xuebao/Journal of Plasticity Engineering

2016-4-28

In many PID control research, a step signal is often given to identify the PID parameter values. However, in this paper, through many simulations and experiments, the result can be obtained that there should be different PID parameters for the same system given different signals. And by the simulation and analysis of a full hydraulic straightening machine model, the result is further verified that the specic parameter values of K _P, K _I and K _D should be given to the PID controller when the system is given a different signal. The good theoretical guidance and practical application value can be obtained by the result of this paper.

Huajun Zhang;庆学 黄;Long Quan

ICIC Express Letters, Part B: Applications

2012-6

The yield stress changes during the straightening process, because of the Bauschinger effect. This effect leads to a different reduction rate in each straightening roller. To accurately estimate the straightening effect of the rolled piece, the Bauschinger effect must be considered in calculating the reduction rate. In this paper, the straightening model is described by the fast multipole boundary element method. The Bauschinger effect model is discussed in the elastic loading region and elastic plastic loading region. Young's modulus reduction and the reverse yield stress reduction are obtained for the straightening force model. The straightening force formula including the Bauschinger effect is determined by analyzing the tension and compression processes. This formula reflects the changes of the yield stress and the straightening force in the tension and compression processes. It is concluded that the Bauschinger effect is a very important factor for the precise estimation of the straightening force.

Hai Lian Gui;Qiang Li;庆学 黄

Mathematical Problems in Engineering

2015

This paper introduces the principle in the application of eddy current technology to detect defects on the surface of aluminum profile and several factors of detecting the depth and precision. On this basis it designs a set of closed-loop system which can be used for the detection and repair of defects in the production line, and outlooks its academic significance and application prospect.

Jian Jun Hao;庆学 黄;Xue Liang Zhang

2011

In this paper, a new Level-2-Computer control system is developed for heat-furnace in plate steel heat treatment line. The process layout, Level-2-Computer control system, network Structure for Level-2, software development environment, and some important calculation formulas for mathematical model for heat-furnace, have been represented, as well as the flow chart of main program for mathematical model. A large amount of operation data shows that the system is reliable, the efficiency of heat-furnace has been increased greatly, and a lot of energy has been saved. Such control system can also provide a lot of reliable real-time data for further on-line technology equipments. Moreover, a useful discovery for energy-saving emission reduction was made to develop advanced heat-furnace process control system.

Hongjie Li;Xiulian Gong;Jianmei Wang;庆学 黄

2009

Based on experimental results and theoretical analysis at different temperatures and time of unit diffusion quantity, the chemical reaction rate in the reaction process between iron and molten tin, is investigated within the range of 260∼350°C. The results indicate that the chemical reaction rate at different time decreases rapidly with the time at the same temperature, it take about four minutes to cease. Morever, the numerical value of the reaction rate at different time are close and decrease with the increasing of the temperature.

Hai Bin Li;庆学 黄;Jian Mei Wang;Hai Lian Gui;Qin Ma

2012

This paper researches the stability of the nonlinear system taking the hydraulic system of double-side rolling shear as an example. The hydraulic system of double-side rolling shear uses unsymmetrical electro-hydraulic proportional servo valve to control the cylinder with single piston rod, which can make best use of the space and reduce reversing shock. It is a typical nonlinear structure. The nonlinear state-space equations of the unsymmetrical valve controlling cylinder system are built first, and the second Lyapunov method is used to evaluate its stability. Second, the software AMEsim is applied to simulate the nonlinear system, and the results indicate that the system is stable. At last, the experimental results show that the system unsymmetrical valve controlling the cylinder with single piston rod is stable and conforms to what is deduced by theoretical analysis and simulation. The construction and application of Lyapunov function not only provide the theoretical basis for using of unsymmetrical valve controlling cylinder with single piston rod but also develop a new thought for nonlinear stability evaluation.

Jun Wang;庆学 黄;Gaocheng An;Qisong Qi;Binyu Sun

Review of Scientific Instruments

2015-10-1

Nano-magnetite (Fe₃O₄) particles have a potential to lead to the formation of lubrication tribofilm that reduces the friction and wear in hot steel strip rolling. In this paper, an attempt to fabricate the oxide film with magnetite precipitates from thermally-grown wustite (Fe_1-xO) layer during isothermal cooling of low carbon microalloyed steel, was obtained. The precipitation behaviors were investigated on Gleeble 3500 thermo-mechanical simulator under the humid air with water vapour content of 19.5vol%. Several types of magnetite precipitates were examined using scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. The tribological properties of magnetite precipitates were investigated in pin-on-disc configuration. It was found that the dispersed magnetite particles originate from either the pro-eutectoid precipitation above 570°C or the partial decomposition of wustite below 570°C. The oxide film on the presence of free particles during eutectoid precipitation could be a lubricant and consequently resist wear, particularly for the oxide scale with a typical thickness in the range of 8 to 11μm in dry air and moisture atmosphere. Furthermore, characterisation and precipitation process of the oxide scale are discussed, with respect to a probable mechanism to explain the lubricated properties has been proposed.

Xianglong Yu;Zhengyi Jiang;Dongbin Wei;Cunlong Zhou;庆学 黄;Daijun Yang

Wear

2013-4