Deformation behavior of the surface defects of low carbon steel in wire rod rolling

Son, Il‐Heon; Jd, Lee; Choi, Seong-Soo; Dl, Lee; Im, Yong‐Taek

doi:10.1016/j.jmatprotec.2007.11.129

Cited by 23 publications

(6 citation statements)

References 9 publications

(5 reference statements)

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“…For instance, the temperature of the outer surface could be dropped below 500 • C at the hard contact area of the rod with rolls, which can make different microstructures and mechanical properties among surface areas [2,27]. Furthermore, it could induce surface defects of a rod during shape rolling, i.e., surface flaws [1,28], abnormal grain growths [29], decarburizations, and martensite transformations in the surface area. Accordingly, it is necessary to analyze the rod temperature for at least the following four regions in order to fully understand the thermal behavior of the rod during hot shape rolling: center, hard contact surface, soft contact surface, and non-contact surface.…”

Section: Measured Temperature Of a Workpiece With Areamentioning

confidence: 99%

Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling

Hwang¹

2020

Processes

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The thermal behavior of a rod during the hot shape rolling process was investigated using the off-line hot rolling simulator and numerical simulation. Additionally, it was compared with a plate during the flat rolling process to understand the thermal behavior of the rod during the hot rolling process in more detail. The temperature of the rod and plate during the hot rolling process was measured at several points with thermocouples using the rolling simulator, and then the measured temperature of each region of a workpiece was analyzed with numerical simulation. During hot rolling process, the temperature distribution of the rod was very different from the plate. The temperature deviation of the rod with area was much higher than that of the plate. The variation in effective stress of the rod along the circumferential direction can induce the temperature difference with area of the rod, whereas the plate had a relatively lower temperature deviation with area due to the uniform effective stress on the surface area. The heat generation by plastic deformation during the forming process also increased the temperature deviation of the rod with area, whereas strain distribution of the plate during flat rolling contributed to the uniformity of temperature of the plate with area. The higher temperature deviation of the rod along the circumferential and radial directions during the shape rolling process can increase the possibility of occurrence in surface defects compared to the plate during flat rolling.

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Section: Measured Temperature Of a Workpiece With Areamentioning

confidence: 99%

Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling

Hwang¹

2020

Processes

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“…And what is similar with the Fig.25 is that the crack width decreases as the rolling pass increases. 28 shows the values of contact pressure of transversal crack on slab corner during V 1 , V 2 , V 3 rolling process under different groove fillet radius of grooved edger roll. From the figure, it could be found that the value of contact pressure of transversal crack increases with the groove fillet radius increasing during V 1 rolling process (from 80MPa to 100MPa).…”

Section: > Contact Pressurementioning

confidence: 99%

FE Analysis of Evolution of Defects during Rolling

Yu¹

2010

Finite Element Analysis

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Defects might appear in materials, such as cracks, inclusions. The evolution behavior of defects in steels during rolling severely affects the rolled products quality. In this chapter, the author summed up the previous researches on the evolution of cracks and inclusions during rolling, mainly contains the researches on the evolution of surface cracks by 2D thermo-mechanical FEM, the evolution of surface cracks during vertical-horizontal (V-H) rolling by 3D FEM, the evolution of internal cracks during V-H rolling, the evolution of inclusions during flat rolling. Evolution of surface cracks by 2D thermo-mechanical FEMSince the brittle fracture model proposed by Griffith last century, a large number of researchers and engineers have carried out a lot of work that focuses on the behavior of cracks. The research reports on the appearance and the propagation of cracks in rolled steels during rolling were investigated [22~25]. Considerable investigations have been carried out on applying FEM for simulation of the propagation and closure of cracks in materials during rolling. A self-healing shape memory alloy (SMA) composite was simulated via a finite element approach that allows crack to propagate in a brittle matrix material by Burton, et al [26]. The SMA wires were carefully (1) where  is density; c is specific heat; k is coefficient of heat conductivity; q  is internal heat source strength, which is the plastic work done of slab deformation during rolling.where m is coefficient of heat transform by plastic work done, 95 .During hot rolling, the thermal transfers between the slab surface and the external environment contain two ways: heat emission and convection current. When the slab is not in the deformation zone, the heat radiation is much larger than the heat convection which could be neglected. According to the Stefan-Boltzman equation,S is the coefficient of Stefan-Boltzman; S B is the blackness on slab surface, T is the slab surface temperature;  T is the temperature of environment. The heat transfers between the slab surface and the work roll is calculated by the Eq. (4). ) (where h i is the coefficient of convective heat transfer between the slab and the roll; T R is the temperature of roll. The coupled thermal-mechanical method is solved by dynamic explicit approach [35]. The heat transfer equations are integrated using the explicit forward-difference time integration rule:

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“…Compared to extensive studies on crack initiation and propagation in metallic materials performed during the last decades, there are few reports on crack healing in metals. Based on the existing researches on crack healing in metallic materials, the healing methods mainly include electro pulsing treatment [2,3,4,5], heat treatment [6,7,8,9], and hot plastic deformation [10,11,12]. From the previous research, the cracks with a width less than 50 µm and a length less than 150 µm could be healed by different healing methods.…”

Section: Introductionmentioning

confidence: 99%

Crack Healing and Mechanical Properties Recovery in SA 508–3 Steel

et al. 2019

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Internal cracks could be healed under the process of hot plastic deformation. In this study, mechanical properties recovery after crack healing in SA 508–3 steel were investigated. Microstructures of the crack healing zones were observed using an optical microscope (OM) and electron back scattered diffraction (EBSD) technology, and the recovery degrees of mechanical properties in the crack healing zones with the healing temperature and a reduction ratio were tested systematically. The results showed that the internal cracks in SA 508–3 steel disappeared and were replaced by newly formed grains, achieved by recrystallization and abnormal grain growth. The tensile properties of crack healing zones could be fully restored, while their impact and low cycle fatigue properties could only be partially achieved. The recovery degrees of mechanical properties in crack healing zones increased with increasing the healing temperature and reduction ratio in the temperature range of 950–1050 °C. When the temperature was above 1150 °C, the impact properties began to deteriorate because of grain coarsening and larger MA (martensite–austenite) constituents. The microstructural evolution of the crack zone in the SA 508–3 steel was sketched.

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Deformation behavior of the surface defects of low carbon steel in wire rod rolling

Cited by 23 publications

References 9 publications

Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling

Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling

FE Analysis of Evolution of Defects during Rolling

Crack Healing and Mechanical Properties Recovery in SA 508–3 Steel

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