scholarly journals Root Cause Analysis of Surface Cracks in Heavy Steel Plates during the Hot Rolling Process

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 801 ◽  
Author(s):  
Abbas Bahrami ◽  
Mahdi Kiani Khouzani ◽  
Seyed Amirmohammad Mokhtari ◽  
Shahin Zareh ◽  
Maryam Yazdan Mehr

This paper investigates the root cause of the formation of surface cracks on hot-rolled C–Mn constructional steel heavy plates. Cracks are rather evenly distributed over the surface in the form of colonies of cracks. Samples were cut from the heavy plate. The microstructure of samples in the as-cast and hot-rolled states were studied using optical and electron microscopes as well as energy dispersive X-ray spectroscopy (EDS). Results show that cracks are heavily oxidized. De-carburized areas are also seen alongside cracks. The crack tip is in the form of a deer-horn, indicating that crack branching has taken place during deformation. The crack initiation sites are V-shaped grooves on the surface of as-cast slabs. Correlations between microstructures, processing parameters, and crack formation are discussed.

2020 ◽  
Vol 989 ◽  
pp. 699-704
Author(s):  
Nikita S. Deryabin ◽  
Sergey M. Chernyshev ◽  
Sergey N. Veselkov

Under the current conditions, the consumption of special purpose alloys or steels is growing. This is due to the development of the import substitution program. It should be noted, that such materials possess specific deformation behavior, which requires providing particular conditions of a hot rolling process. One of the characteristics of the deformation behavior is the narrow thermal plastic range. Therefore, it is necessary to conduct a hot rolling in several stages, which include interchange of heating and rolling processes. For the purpose to resolve the issue, the experience of the multilayer hot rolling of plates has been investigated where all advantages of this way of a hot rolling process were used. Based on the method of the multilayer hot rolling, the pack rolling has been developed which gives the possibility of production of hot-rolled plates from special purpose alloys or steels.


2012 ◽  
Vol 706-709 ◽  
pp. 2101-2106
Author(s):  
Xiu Hua Gao ◽  
Hui Fang Lan ◽  
Lin Xiu Du ◽  
Chun Lin Qiu

The low cost Q460 and Q550 steel plates were produced in the 4200mm wide and heavy plate mill using Normal Hot Rolling and High Rate Cooling (NHR+HRC) process. The effect of both rolling processes on microstructure and mechanical property was studied. The results indicate that new type process can realize the good match between microstructure and mechanical properties. Meanwhile the new technology can short rolling time, reduce alloying addition, and improve the output of mill, it is also promote iron and steel industry developing continuously.


2011 ◽  
Vol 474-476 ◽  
pp. 325-329 ◽  
Author(s):  
Jie Jin ◽  
Gang Huang

Establishment of numerical model for hot rolled bar and analysis the changes from the discrete points on surface during the hot bar rolling process (includes velocity, displacement, equivalent stress, equivalent strain). And the position of surface defects can be effectively predicted form this. Compared with the actual hot rolling bar production, numerical simulation was in good agreement with it. So that the numerical simulation analysis has practical significance for optimizing processing parameters and process design to ensure product quality.


2005 ◽  
Vol 488-489 ◽  
pp. 337-340
Author(s):  
Dong Yim Chang ◽  
Bong Sun You ◽  
Bum Sik Kam ◽  
Won Wook Park

AZ31 magnesium plates with 1mm in thickness were fabricated by casting and subsequent hot rolling process. Both wheel-band continuous casting (modified Properzi) and horizontal continuous casting (HCC) machine were designed and employed to produce AZ31 alloy plates. The plates with 5x50mm in size produced by modified Properzi process exhibited good surface qualities that were sustained during following rolling process. Surface qualities of HCC plates with 120x30mm in size were very sensitive depending on the processing parameters. Homogenization treatment or surface machining before rolling was effective to get good thin plate. By means of rolling process, microstructures were refined effectively to the size of 7~10µm.


2011 ◽  
Vol 295-297 ◽  
pp. 1267-1273
Author(s):  
Yu Yan Liu ◽  
Xing Qian Li ◽  
Zi Li Jin

Based on CSP technics, using Gleeble1500-D hot simulation machine, making the single, dual, multi-pass compression experiment of Q345B steel with rare earth Nd respectively, different deformation conditions influencing Q345B steel of recrystallization behavior and the microstructure evolution rule in the hot rolling process have been studied. The results show that: the single, dual-pass experiments of Q345B steel with rare earth Nd are according with general experimental rules. According to single, dual-pass results, we establish multi-pass compression project. In that project, the grain samples with rare earth element Nd are finer than others. It explains that appending rare earth Nd has the obvious function of refining grains. At the same time, the degree of refining grains is different in the different project. It explains that in order to obtain fine grains, we should choose feat technics. By contrast, we can educe that the grains are more fine and uniform in a project.


2011 ◽  
Vol 399-401 ◽  
pp. 264-267
Author(s):  
Hai Yan Wang ◽  
Hui Ping Ren ◽  
Le Han ◽  
Zi Li Jin ◽  
Hao Sun

Microstructure of X80 pipeline steel with different hot rolling process was compared using Optical microscopy (OM), Bulk X-ray texture and micro orientation analysis was carried out by Orientation distribution function (ODF) and Electron back-scattered diffraction (EBSD), to analyze the various texture components of the pipeline steels under two different rolling processes. The results show that the final microstructures under the two schedules both present typical acicular ferrite characteristic. On the other side, the corresponding textures were found mainly comprised of two fibers in the rolling and normal direction in hot rolled X80 steel plate, there were obvious {112} , {110} , and {111} fiber, which seemed to be related with the mechanical properties anisotropy. Therefore, the influences of the microstructure and texture on the anisotropy were also discussed in this paper.


2011 ◽  
Vol 291-294 ◽  
pp. 137-140
Author(s):  
Yao Min Zhu ◽  
Qiu Ran Gao ◽  
Feng Zhang Ren ◽  
Shi Jie Fang

The effects of the hot-rolling process on microstructures and strength were investigated for two kinds of magnesium alloy Mg-Zn-Y and Mg-Zn-Y-Nd. In comparison with the as-cast alloys, the tensile strength of Mg-Zn-Y and Mg-Zn-Y-Nd both increases 45%, whereas their elongation decreases 73%, 60% via hot-rolling process, respectively. The results show that the dynamic recrystallization process and the pining effect of I-phase during hot rolling contribute to the fine-grained structure formation. The hot-rolling process has refined the grain size greatly.


2021 ◽  
Vol 11 (12) ◽  
pp. 5526
Author(s):  
Hyun-Hee Kim ◽  
Sung-Jin Kim ◽  
Sung-Min Yoon ◽  
Yong-Joon Choi ◽  
Min-Cheol Lee

In a hot rolling process, excessive friction between rollers and steel plates may lead to the formation of scratches on the steel plate. To reduce scratch formation in the finishing mill of the hot rolling process, two techniques are proposed in this work: flying touch and velocity synchronization. The proposed flying touch method can reduce the impact of the generated force when the upper roller collides with the steel plate. In addition, the proposed velocity synchronization method can decrease the frictional force resulting from the velocity difference between the rollers and steel plate. The effectiveness of the proposed methods was demonstrated through simulations and experiments using a 1/40 downscaled hot rolling simulator. The simulations and experimental results demonstrate that the proposed methods can reduce the magnitudes of friction and impact forces that lead to scratch formation on the steel plates in the hot rolling process.


2017 ◽  
Vol 750 ◽  
pp. 124-128
Author(s):  
Yunus Turen ◽  
Didem Güzel ◽  
Huseyin Zengin ◽  
Yavuz Sun ◽  
Hayrettin Ahlatci

In this study, the effect of Sn addition on corrosion resistance of as-cast and hot rolled AZ31 magnesium alloy was investigated. Sn additions were made by 0.2 wt%, 0.5 wt% and 1 wt%. An electric resistance furnace was used to produce alloys. Hot rolling process was performed at 350 °C by 40% thickness reduction at one rolling pass. Microstructure characterizations were performed by optical (OM) and scanning electron microscope (SEM). Immersion tests and electrochemical analyses were performed to investigate the corrosion resistance of the alloys. A 3.5% NaCl working solution at room temperature was used in both corrosion tests. The results showed that Sn addition decreased the primary dentrite size and restricted the growth of secondary dentritic arm. The as-cast structures transformed to dynamically recrystallized grain structures after hot-rolling process in all the alloys. Corrosion resistance of AZ31 magnesium alloy tended to decrease with Sn addition. This decrease was more clear in homogenized and hot-rolled states while there were some flactuations in as-cast states.


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