Papers by Keyword: Surface Defect

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Authors: Sheng Nan Yang, Zheng Yi Jiang, Dong Bin Wei
Abstract: The behaviour of the surface defects on the continuous casting slab during hot rolling is investigated using the commercial FE-code LS-DYNA. The thermo-elastic-plastic material model is chosen in the simulation models, and the material implemented in the simulation is the austenitic stainless steel 304. The numerical results show the significant morphological changes of the surface defects during hot rolling and afford valuable indications for a deeper understanding of the underlying process. An accelerated crack growth and propagation are observed for the edge cracks, and the closure behaviour is found in the transverse and longitudinal cracks. The effect of temperature is significant on both the roll and the strip in hot rolling process. The developed models consider different types of mesh and element, thermal conditions, and rolling schedules. The predicted relationship between rolling conditions, the temperature distribution of crack, and the full history of temperature variation are discussed in this study.
Authors: Akira Miyasaka, Jun Norimatsu, Keisuke Fukada, Yutaka Tajima, Yoshiaki Kageshima, Daisuke Muto, Michiya Odawara, Taichi Okano, Kenji Momose, Yuji Osawa, Hiroshi Osawa, Takayuki Sato
Abstract: The production of 150 mm-diameter SiC epitaxial wafers is the key to the spread of SiC power devices. We have developed production technology of the epitaxial growth for 4° off Carbon face (C-face) 4H-SiC epitaxial layers on 150 mm diameter substrates. Several growth parameters and hardware were optimized to obtain high uniformity wafers. We have succeeded in fabricating high quality C-face wafers with smooth surface and high uniformity.
Authors: Nicolas G. Wright, Konstantin Vassilevski, Irina P. Nikitina, Alton B. Horsfall, C. Mark Johnson, Praneet Bhatnagar, Peter Tappin
Abstract: New results are presented of a surface trench defect observed during anneal of room temperature Al implants. The size of the surface defect is proportional to anneal temperature and occurs predominantly in the implanted zone. Signs of lattice strain are observed outside the implanted zone as well.
Authors: Xuan Wang, Wei Liu, Hui Cao, Dong Ping Ma
Abstract: Steel surface defect detection is the key point of this research. The paper mainly focuses on the image processing and image feature extraction of the steel plate surface. The paper also focuses on the calculating procedure and results of the fractal dimension in different defects images. It can be concluded from the results of the study, fractal dimension of the defect images becomes an important feature of the steel plate surface image pattern recognition.
Authors: Wu Bin Li, Chang Hou Lu, Jian Chuan Zhang
Abstract: In order to guarantee the steel bar quality, we describe the category of steel bar surface defects in details. Generally, there are about two main categories of steel bar surface defects which include linear and area-like defects. Secondly, the characteristics of the steel bar surface image are analyzed at large. Both of them support a foundation for the future inspection of steel bar surface quality.
Authors: Feng Yan, Chun Li Liu, Ke Qiang Yu
Abstract: In producing stainless steel cold rolling strip, stripe and decorative pattern shape defects occur on the surface, and influence its quality. This paper uses the spot investigation, defects microscopic analysis and scanning electron microscopy spectrometer methods in order to give a detailed analysis about surface defects, discusses the essence of defects, causes and effects process, puts forward valuable suggestions and provides reliable data for the actual production.
Authors: Pavel Gejdoš, Lenka Klakurková, Martin Juliš, Miroslava Horynová, Michaela Remešová, Eduard Hégr
Abstract: Alkaline blackening is one of the most popular surface treatment technology of components with the requirement for higher surface corrosion resistance, increased hardness, and the decorative appearance.This contribution deals with the appearance of surface defects on carburized steel components after the process of alkaline blackening, which appeared to be red shiny stains on an otherwise black matte surface of the component. The occurrence of defects on surface was observed several days after the alkaline blackening process. By means of metallographic methods, direct connection between surface defects and the microstructure of the material was found.Contribution further deals with the influence of microstructure and technological parameters on the quality of the final surface layer of the components.
Authors: X.Z. Zhang, Zheng Yi Jiang, A. Kiet Tieu, Hong Tao Zhu, Z.W. Tian
Abstract: There are many defects on the surface of continuous casting slab, such as corner cracks, longitudinal cracks etc. To analyze the cracks and determine their locations, two-dimensional heat transfer mathematical model and thermal elasto-plastic stress model of slab casting were established in this paper. The process of solidification, temperature field, and thermal stress distribution on slab surface were analyzed using finite element method. The effect of thermal stress on the cracks on the slab surface was discussed. The location of the cracks caused by thermal stress can be predicted. This is useful for finding approaches to overcome these defects.
Authors: Qiang Song
Abstract: This paper is concerned with the problem of automatic inspection of hot-rolled plate surface using machine vision. An automated visual inspection (AVI) system has been developed to take images of external hot-rolled plate surfaces and the detailed characteristics of the sensor system which include the illumination and digital camera are described. An intelligent surface defect detection paradigm based on morphology is proposed to detect structural defects on plate surfaces. The proposed method has been implemented and tested on a number of hot-rolled plate surfaces. The results suggest that the method can provide an accurate identification to the defects and can be developed into a commercial visual inspection system.
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