Comparative study of two rolling bond process for super-thick Q235B

In paper, two rolling bond processes for heavy-gauge steel plate Q235B were studied and the processes were simulated by MARC software. The mechanical properties and microstructure at the interface were comparative analyzed for the two bonded plates using different rolling process. Using MARC software analysis for two rolling process, the ratio of equivalent stress in rolling process /yield stress in current temperature from surface to center portion was relatively uniform for rolling bonded

Simulation of Bimetallic Bush Hot Rolling Bonding Process

Three-dimensional model of bimetallic bush was established including the drive roller and the core roller. The model adopted the appropriate interface assumptions. Based on the bonding properties of bimetallic bush the hot rolling process was analyzed. The optimum reduction ratio of 28% is obtained by using the finite element simulation software MARC on the assumption of the bonding conditions. The stress-strain distribution of three dimensions was research assumptions to interface deformation of rolling. At the same time, based on the numerical simulation, the minimum reduction ratio 20% is obtained by using a double metal composite bush rolling new technology from the experiment research. The simulation error is not more than 8%

Study on the Control Method of Mine-Used Bolter Manipulator Based on Fractional Order Algorithm and Input Shaping Technology

Mine-used bolter is the main equipment to solve the imbalance of excavation and anchor in well mining, and the manipulator is the main working mechanism of mine bolt drilling rig. The manipulator positioning requires high rapidity and stability. For this reason, this paper proposes a composite control method of “input shaping + fractional order PDμ control”. According to the mathematical model of the valve-controlled cylinder, the fractional-order controller PDμ is developed. At the same time, the input shaping is used to feed forward the accurate positioning and path planning of the manipulator, which not only improves the robustness of the system, but also shortens the stability time of the system and restrains the maximum amplitude of the system vibration. In this paper, the control effects of fractional order PDμ controller and integer order PD controller are compared. The results show that the maximum amplitude of the control system is reduced by 75% and the stabilization time is reduced by 60% after using the fractional order PDμ controller, which fully reflects the superiority of the fractional order controller in response speed, adjusting time, and steady-state accuracy. Finally, the control effects of “input shaping + fractional order PDμ control” and fractional order PDμ controller on the stability of the system are compared. The maximum amplitude of the system was reduced by 50% by using “input shaping + fractional order PDμ control”. Numerical simulation confirms the feasibility and effectiveness of the composite control method. This composite control method provides theoretical support for the precise positioning of the manipulator, and the high stability and high safety of the manipulator also expand the application scope and depth of the composite control method

Numerical Simulation of One-Dimensional Fractional Nonsteady Heat Transfer Model Based on the Second Kind Chebyshev Wavelet

In the current study, a numerical technique for solving one-dimensional fractional nonsteady heat transfer model is presented. We construct the second kind Chebyshev wavelet and then derive the operational matrix of fractional-order integration. The operational matrix of fractional-order integration is utilized to reduce the original problem to a system of linear algebraic equations, and then the numerical solutions obtained by our method are compared with those obtained by CAS wavelet method. Lastly, illustrated examples are included to demonstrate the validity and applicability of the technique

The effects of vacuum annealing temperatures on the microstructure, mechanical properties and electrical resistivity of Mg-3Al-1Zn alloy ribbons

This paper investigates the influence of vacuum annealing temperature on the microstructure, mechanical properties and electrical resistivity of Mg-3Al-1Zn rapid solidification (RS) magnesium ribbons. The results indicate that when the annealing temperature is increased, the grain size of the ribbons is dramatically reduced from 10 to 1 μm. The highest break stress and micro-hardness is obtained at 673 K. These effects are ascribed to the dispersion strengthening caused by the high amount of fine nanoparticles distributed in the material. Electrical resistivity-temperature (ρ-T) curves have been used to provide useful information about the effects of the annealing temperature on the grain size, grain orientation and crystal structure of the ribbons. In this way, a new lightweight electric wire or connection cable line could be produced which would have good electromagnetic interference (EMI)

Effects of grain boundaries in oxide scale on tribological properties of nanoparticles lubrication

The characters of grain boundaries in oxide layers formed on substrates influence adhesion and friction behaviour, surface fracture and wear during high temperature steel processing. In this work, an electron backscattered diffraction (EBSD) analysis was conducted to investigate the role of surface grain boundary and orientation in magnetite (Fe3O4)/haematite (α-Fe2O3) scale during hot rolling, and further evaluate their effects on tribological properties of water-based nanoparticles lubrication. The results demonstrate that Fe3O4 (100) plane is strongly sensitive to the surface characteristics as the minimisation of surface energy. Coincident site lattice (CSL) boundaries in microstructure is in presence of Σ3 in the Fe3O4 and Σ13b in the Fe2O3 of the substrates subjected to a thickness reduction of 28% and cooling rate of 28 ° C/s. This is due in great part to the changes in crystal slip systems. These low-Σ CSL boundaries in oxide scale offer obstacles to the propagation of cracks, where some of nanoparticles collected would be trapped at the interface and thereby may cause high wear rates. A lubrication mechanism is proposed to explain the grain boundary effect on nanoparticles lubrication, and further to determine the dependence of frictional behaviour on surface energy, crystallographic preferred orientation (microtexture) and crystal structure. These results provide an intriguing new insight into the application of water-based lubricant with graphite nanoparticles

Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD

This work presents a fine microstructure and local misorientation study of various oxide phases in the tertiary oxide scale formed on a hot-rolled steel strip via electron back-scattering diffraction (EBSD). Local strain in individual grains of four phases, ferrite (α-Fe), wustite (FeO), magnetite (Fe3O4) and hematite (α-Fe2O3), has been systematically analysed. The results reveal that Fe3O4 has a lower local strain than α-Fe2O3, in particular, on the surface and inner layers of the oxide scale. The multiphase oxides along the cracking or α-Fe2O3 penetration generally develop a high local misorientation. Localised stain along the cracks demonstrates that the misorientation tends to be strong near grain boundaries. The high fraction of small Fe3O4 grains accumulate at the oxide-substrate interface, which leads to a dramatic increase in the intensity of local stain. This variation is due mainly to the phase transformation among the oxide phases, i.e., the Fe3O4 particles during their nucleation and growth. The combined action of stress relief and re-oxidisation is proposed to explain the formation of Fe3O4 seam at the oxide-steel interface. The present study offers an intriguing insight into the deformation behaviour of the tertiary oxide scale formed on steels, and may help with understanding the stress-aided oxidation effect of metal alloys