scholarly journals Effect of a Novel Hot-core Heavy Reduction Rolling Process after Complete Solidification on Deformation and Microstructure of Casting Steel

2019 ◽  
Vol 59 (12) ◽  
pp. 2283-2293 ◽  
Author(s):  
Hai-jun Li ◽  
Tian-xiang Li ◽  
Rui-hao Li ◽  
Mei-na Gong ◽  
Zhao-dong Wang ◽  
...  
2020 ◽  
Vol 14 ◽  
Author(s):  
Xiao-bin Fan ◽  
Hao Li ◽  
Yu Jiang ◽  
Bing-xu Fan ◽  
Liang-jing Li

Background: Rolling mill vibration mechanism is very complex, and people haven't found a satisfactory vibration control method. Rolling interface is one of the vibration sources of the rolling mill system, and its friction and lubrication state has a great impact on the vibration of the rolling mill system. It is necessary to establish an accurate friction model for unsteady lubrication process of roll gap and a nonlinear vibration dynamic model for rolling process. In addition, it is necessary to obtain more direct and real rolling mill vibration characteristics from the measured vibration signals, and then study the vibration suppression method and design the vibration suppression device. Methods: This paper summarizes the friction lubrication characteristics of rolling interface and its influence on rolling mill vibration, as well as the dynamic friction model of rolling interface, the tribological model of unsteady lubrication process of roll gap, the non-linear vibration dynamic model of rolling process, the random and non-stationary dynamic behavior of rolling mill vibration, etc. At the same time, the research status of rolling mill vibration testing technology and vibration suppression methods were summarized. Time-frequency analysis of non-stationary vibration signals was reviewed, such as wavelet transform, Wigner-Ville distribution, empirical mode decomposition, blind source signal extraction, rolling vibration suppression equipment development. Results: The lubrication interface of the roller gap under vibration state presents unsteady dynamic characteristics. The signals generated by the vibration must be analyzed in time and frequency simultaneously. In the aspect of vibration suppression of rolling mill, the calculation of inherent characteristics should be carried out in the design of rolling mill to avoid dynamic defects such as resonance. When designing or upgrading the mill structure, it is necessary to optimize the structure of the work roll bending and roll shifting system, such as designing and developing the automatic adjustment mechanism of the gap between the roller bearing seat and the mill stand, adding floating support device to the drum shaped toothed joint shaft, etc. In terms of rolling technology, rolling vibration can be restrained by improving roll lubrication, reasonably distributing rolling force of each rolling mill, reducing rolling force of vibration prone rolling mill, increasing entrance temperature, reducing rolling inlet tension, reducing strip outlet temperature and reasonably arranging roll diameter. The coupling vibration can also be suppressed by optimizing the hydraulic servo system and the frequency conversion control of the motor. Conclusion: Under the vibration state, the lubrication interface of roll gap presents unsteady dynamic characteristics. The signal generated by vibration must be analyzed by time-frequency distribution. In the aspect of vibration suppression of rolling mill, the calculation of inherent characteristics should be carried out in the design of rolling mill to avoid dynamic defects such as resonance. It is necessary to optimize the structure of work roll bending and roll shifting system when designing or reforming the mill structure. In rolling process, rolling vibration can be restrained by improving roll lubrication, reasonably distributing rolling force of each rolling mill, increasing billet temperature, reasonably arranging roll diameter and reducing rolling inlet tension. Through the optimization of the hydraulic servo system and the frequency conversion control of the motor, the coupling vibration can be suppressed. The paper has important reference significance for vibration suppression of continuous rolling mill and efficient production of high quality strip products.


2010 ◽  
Vol 3 (1) ◽  
pp. 65-71
Author(s):  
Armindo Guerrero ◽  
Javier Belzunce ◽  
Covadonga Betegon ◽  
Julio Jorge ◽  
Francisco J. Vigil

2020 ◽  
Vol 982 ◽  
pp. 121-127
Author(s):  
Shuo Li ◽  
Qing Dong Zhang

A cylindrical indenter was designed to simulate the roller and 304 stainless steel / Q235A carbon steel plate with different roughness were bonded together. The interfacial bonding behavior was investigated by SEM, ultrasonic “C” scanning detection and nanoindentation test. The result reveal that with the increase of contact pressure between interfaces, the atoms of dissimilar metals begin to diffuse across interfaces in some regions, then form island-like bonding regions, and eventually extend to the whole interface. There are no obvious cracks on the surface of stainless steel and carbon steel after deformation. The cold roll-bonding mechanism of stainless steel and carbon steel is that elements on both sides of the interface diffuse and form a shallow diffusion layer under pressure to ensure the joint strength, and the joint bonding strength is greater than the strength of carbon steel matrix. In addition, the surface morphology of base metal has a great influence on the interfacial bonding quality. The higher surface roughness values increases the hardening degree of rough peak, which makes real contact area difficult to increase and reduce the interfacial bonding quality.


Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 384
Author(s):  
Tomasz Dembiczak ◽  
Marcin Knapiński

Based on the research results, coefficients in constitutive equations, describing the kinetics of dynamic, meta-dynamic, and static recrystallization in high-carbon bainitic steel during hot deformation were determined. The developed mathematical model takes into account the dependence of the changing kinetics in the structural size of the preliminary austenite grains, the value of strain, strain rate, temperature, and time. Physical simulations were carried out on rectangular specimens. Compression tests with a flat state of deformation were carried out using a Gleeble 3800. Based on dilatometric studies, coefficients were determined in constitutive equations, describing the grain growth of the austenite of high-carbon bainite steel under isothermal annealing conditions. The aim of the research was to verify the developed mathematical models in semi-industrial conditions during the hot-rolling process of high-carbon bainite steel. Analysis of the semi-industrial studies of the hot-rolling and long-term annealing process confirmed the correctness of the predicted mathematical models describing the microstructure evolution.


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