科创中国

Based on the microstructure evolution of AZ31 magnesium alloy during hot compression, the recrystallization grain size model and dynamic recrystallization percentage model were established on the cellular automaton(CA) model. The dislocation density model, the critical dislocation density model, the nucleation rate model and grain growth model of magnesium alloy AZ31 were deduced by thermal compression experiments under different deformation conditions. Combining the specific evolution rules of cellular automata, the cellular automata model was established. The simulation results and accuracy of cellular automata were verified by stress-strain curves and grain size. Based on the experimental data and the JMAK theory, the recrystallization grain size model and dynamic recrystallization percentage model were deduced. By DEFORM-3D analysis software, the change of grain size distribution and dynamic recrystallization percentage distribution in deformation were obtained.

Zhibing Chu;Duo Zhang;Lianyun Jiang;立峰 马;Yugui Li;庆学 黄

Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering

2018-3-1

Electron backscatter diffraction (EBSD) of the microtexture in the tertiary oxide scale after hot rolling were investigated. The surface asperity flattening and grain refinement of Fe₃O₄ were produced at a thickness reduction of 28% and a cooling rate of 28 °C/s. Microtexture development of Fe₃O₄ manifests as a strong θ fibre parallel to oxide growth, including the {100}<001> and {001}<110> textured components, whereas the {0001}〈101〉0> component dominates in α-Fe₂O₃ as the favoured basal slip. The tribological effect of α-Fe₂O₃ at the contact surface of steel and rolls was considered at low and high thickness reductions. The propagation of cracks along the Fe₃O₄ grain boundaries could create a dish to collect nanoparticles during lubrication and thereby changed the wear rates.

Xianglong Yu;Zhengyi Jiang;Jingwei Zhao;Dongbin Wei;济 周;Cunlong Zhou;庆学 黄

Tribology International

2016-1-1

The requirements of the plate straightening process on the response process of hydraulic cylinder in the praxis were studied, a concept of combined given curve was proposed to alleviate the impact of the system with large mass and inertia during the response for the step and ramp signals and its harm on the whole system. Combined with the nonlinear PID control backed up by the tracking differentiator, a composite controller was proposed based on the combined given curves of the displacement, velocity and acceleration. The feasibility and practicality of the proposed algorithm were verified by simulations and the practical application in the full-hydraulic straightening machine.

Hua Jun Zhang;庆学 黄;Long Quan

Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and Technology Edition)

2013-3

In the classical straightening theory, it supposes that the geometric central layer and stress neutral layer are a coincidence. However, there is some offset in fact. This is one of the reasons why straightening force is inaccurate in the straightening process. In this paper, the boundary element subfield method is used to analyze the three-dimension elastic–plastic deformation of a bimetal composite plate in the straightening process. At first, the boundary integral equation of a bimetal composite plate is established by the boundary element subfield method. Then, through analyzing the deformation in the rolled piece straightening, it shows that the geometric central layer does not coincide with the neutral layer. The formula of the neutral layer offset is established and the change law is discussed. At the same time, the influence of the neutral layer offset on the precision of straightening force is researched. From the numerical analysis, it shows that the error of the straightening force reaches to 5% whether considering the neutral layer offset. This demonstrates that the neutral layer offset is one of the important factors to give the straightening force inaccurately. It is ought to consider the neutral layer offset when the model of straightening force is established.

H. L. Gui;立峰 马;X. G. Wang;X. Yang;庆学 黄;Q. Li

Applied Mathematical Modelling

2017-10

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate (CBR) was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12∼1.2 N/m during the soft argon blowing.

Rui Wang;燕平 包;Yihong Li;Aichun Zhao;Yafeng Ji;Xiao Hu;庆学 黄;Jiansheng Liu

2016

For the high-speed angular contact ball bearing, the relationship between the equilibrium equation of the gyroscopic torque of a rolling element and the coefficient of friction between the rolling element and groove is analyzed. The internal load of this ball bearing that sustains a purely axial load is calculated. And the variation rule of the coefficient of friction required by the equilibrium of gyroscopic torque axial force and rotational speed is determined. Calculations show that at a certain rotational speed, the selection of axial force should consider the combined influence of contact force, gyroscopic torque, and coefficient of friction.

Zhao Chunjiang;Yu Xiaokai;庆学 黄;Ge Shidong;Gao Xin

Tribology International

2015-7

When an output curve force is applied to a horizontal servo cylinder with a heavy load, the piston rod bears a dynamic partial load based on the installation and load characteristics, which significantly affects the frequency response and control accuracy of the servo cylinder. Based on this partial load, increased friction can lead to cylinder bore scuffing, leakage, lack of output power, or even system failure. In this paper, a novel asymmetric static-pressure support structure is proposed based on the principle of hydrostatic support. The radial component force of a dynamic partial load is balanced by cooperation between the support oil cushion of the variable hydraulic pressure support structure, oil cushion of the supportive force, and the damper. Adaptive control of the servo cylinder piston rod, guide sleeve, and piston, as well as the cylinder oil film friction between lubricated surfaces is achieved. In this paper, theoretical design and analysis of the traditional hydrostatic bearing structure and novel structure are presented. A hydraulic dynamic shear scissor is used as a research target to derive a structural dynamic model. Comparative simulations are performed using Matlab Simulink. Additionally, flow field analysis of the novel structure is performed, which verifies the rationality and feasibility of the proposed structure and system.

Linan Ma;庆学 黄;立峰 马;Qiangjun Ma;Wenze Zhang;Heyong Han

Chinese Journal of Mechanical Engineering (English Edition)

2019-12-1

Based on experimental results and theoretical analysis at different temperatures and time of unit diffusion quantity, the mixing entropy in the reaction process between iron and molten tin, is investigated within the range of 260∼350°C. The mixing entropy is plotted versus the dimensional time, which showed that the difference value of it at different time was an upward trend. At different temperatures, the mixing entropy of the system increased with the temperature, tin atoms diffusing into the matrix gradually becaming greater, so as to there has been a appreciable increase in the values of mixing entropy. In addition, the mixing entropy's increase trend becomes smoothly with the temperature increasing, and the entropy change of the system is decreasing more obvious with the temperature increasing.

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

2012

Based on rolling-cut simulation, a 3000 mm single-shaft, double-eccentricity and cut-to-length rolling shear of a certain large-scale iron and steel company that adopts asymmetric new-type structure is used as the calculation model by establishing motion path equation of spatial shear mechanism. After comparing and analyzing the shear force on steel plates with asymmetric front and rear, connecting rod force, and horizontal force component of connecting rod, the asymmetric formula is deduced. The asymmetric crank structure can decrease the horizontal force component of connecting rod during rolling-cut process, increase the effective drive force of connecting rod at the period of the maximum shear force, and decrease the extrusion of blade arc on steel plate edge as well. Theoretical analysis results and on-spot steel plate shear quality show that the asymmetric structure is an important means to improve shear capability, decrease blade wear, prolong blade life and improve shear quality.

庆学 黄;Lifeng Ma;Jinbao Li;Jianmei Wang;Qisheng Zhang;Chunjiang Zhao

Jixie Gongcheng Xuebao/Chinese Journal of Mechanical Engineering

2008-5

AZ31B cast rolled magnesium alloy sheets were rolled under conditions with temperature of 350℃ and rolling speed of 0.5 m/s, whose dimension was 150 mm×150 mm×7 mm, and rolling reduction 10%, 20%, and 30%. Then numerical simulation was carried out under these same rolling conditions. Moreover, magnesium alloy sheet's surface temperature field and stress state were analyzed, and then its mathematics model of surface temperature gradient was established. Edge cracks' damage and temperature distribution of finite element numerical simulation's results were analyzed in addition to their microstructure after rolled. Simulated results were compared with experimented. It can be drawn the conclutions that at the same temperature, with rolling reduction increasing, plastic deformation heat of magnesium sheet will increase, but small reduction will promote brittle phase of MgZn₂ and Mg₂Si generated. Therefore, reducing quantities of long strip twins and brittle phase is one of key factors about controlling edge cracks.

立峰 马;Zhining Pang;庆学 黄;Ziyong Ma;Jinbao Lin;Zhigang Li

Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering

2014-9-1