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Surface nanostructure formation mechanism of 45 steel induced by supersonic fine particles pombarding

Journal of University of Science and Technology Beijing 2008年第5期15卷 561-567页

作者： Dema Ba Shining Ma Changqing Li Fanjun Meng Department of Remanufacture Engineering Academy of Armored Force Engineering Beijing 100072 China

By means of supersonic fine particles bombarding （SFPB）,a nanostructured surface layer up to 15 μm was fabricated on a 45 steel plate with ferrite and pearlite phases. To reveal the grain refinement mechanism of SFPB-treated 45 steel,microstructure features of various sections in the treated surface were systematically characterized by X-ray diffraction （XRD）,scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Grain size increases with an increase of depth from the treated surface. Plastic deformation and grain refinement processes are accompanied by an increase in strain. Plastic deformation in the proeutectoid ferrite phases has precedence over the pearlite phases. Grain refinement in the ferrite phases involves： the onset of dislocation lines （Dls）,dislocation tangles （DTs） and dense dislocation walls （DDWs） in the original grains; the formation of fine lamellar and roughly equiaxed cells separated by DDWs; by dislocation annihilation and rearrangement,the transformation of DDWS into subboundaries and boundaries and the formation of submicron grains or subgrains; the successive subdivision of grains to finer and finer scale,resulting in the formation of highly misoriented nano-grains. By contrast,eutectoid cementite phase accommodated strain in a sequence as follows： onset of elongated,bended and shear deformation under deformation stress of ferrites,short and thin cementites with a width of about 20-50 nm and discontinuous length were formed. Shorter and thinner cementites were developed into ultra-fine pieces under the action of high density dislocation and strains. At the top surface,some cementites were decomposed under severe plastic deformation. Experimental evidences and analysis indicate that surface nanocrystallization of 45 steel results from dislocation activities,high strains and high strain rate are necessary for the formation of nanocrystallites.

关键词： surface nanocrystallization grain refinement mechanism microstructure 45 steel

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Solution of an Inverse Problem of Heat Conduction of 45 steel with Martensite Phase Transformation in High Pressure during Gas Quenching

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Journal of Materials Science & Technology 2002年第4期18卷 372-374页

作者： Heming CHENG, Tianchun HE and Jianbin XIEDepartment of Engineering Mechanics, Kunming University of Science and Technology, Kunming 650093, China Dept. of Eng. Mech. Kunming Univ. of Sci. and Technol. Kunming 650093 China

In order to simulate thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heat transfer coefficient is a key parameter. The explicit finite difference method, nonlinear estimation method and the experimental relation between temperature and time during gas quenching have been used to solve the inverse problem of heat conduction. The relationship between surface temperature and surface heat transfer coefficient of a cylinder has been given. The nonlinear surface heat transfer coefficients include the coupled effects between martensitic phase transformation and temperature.

关键词： 45 steel Phase transformation Heat conduction

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Investigation on the Bonding Mechanism of M42 Powder High-speed steel and 45 steel

Investigation on the Bonding Mechanism of M42 Powder High-sp...

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2011 First International Conference on High Performance Structures and Materials Engineering (ICHPSM 2011)

作者： Hang You Xianrui Wang Cui Liang Xiaoqin Ding Xiaoyun Han Jinfu Xu Institute of Materials Science and Engineering East China University of Science and Technology Institute of Materials Engineering Ningbo University of Technology

The sintering of M42 P/M high speed steel followed by jointing to 45 steel had been accomplished at one step by using spark plasma sintering（SPS） *** on the traditional diffusion theory and the designed structure of M42/45 steel joint,the bonding mechanism and models with the interface forming process of the bimetal have been proposed *** jointing and valuation of M42/45 steel interface are a comprehensive synergy process between fusion and diffusion *** former one takes priority at the early sintering process,while the later one becomes dominant over the followed sintering process.

关键词： M42 powder high-speed steel 45 steel SPS Bonding Diffusion

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The Numerical Simulation of No.45 steel in High Speed Cutting

The Numerical Simulation of No.45 Steel in High Speed Cuttin...

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2012 International Conference on Computer Science and Artificial Intelligence(CSAI 2012)

作者： Gui-Qiang Liang Ting-Ting Guo Fei-Fei Zhao BinZhou Vocational College

With Cockroft-Latham criterion of Chip fracture as the criteria of failure, The machining process for 45 steel when high speed machining was numerical simulated by setting up orthogonal cutting finite element method model, and the formation process of collapse chip was abtained. Then the cutting stress curve and the cutting temperature field were analysed, the results showed that the cutting force and the cutting temperature produced larger fluctuations. The numerical imitation results provide foundation for further research for the design of tool geometry size and the cutting mechanism and parameter optimization for 45 steel when high speed machining.

关键词： 45 steel High speed machining Collapse chip Numerical simulation

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ANALYSIS ON MECHANISM OF FRACTURE FOR THE SURFACE-HARDENING steel

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Journal of Wuhan University of Technology(Materials Science) 1995年第4期10卷 18-23页

作者：章桥新张东明黄孝友 Wuhan Univ of Technology Wuhan China

The tensile characteristic of nitrocarburized 45 steel treated by different cooling rates was studied in this work. We had observed a new kind zigzig tensile curve and it showed that the tensile curve and the characte... 详细信息

关键词： 45 steel nitrocarburizing fracture mechanism

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Novel evaluation method for metal workability during cross wedge rolling process

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Advances in Manufacturing 2021年第3期9卷 473-481页

作者： Ming Cheng Ming-Jie Shi Petrenko Vladimir Rui-Xue Wang Shi-Hong Zhang Institute of Metal Research(IMR) Chinese Academy of Sciences(CAS)Shenyang110016People’s Republic of China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026People’s Republic of China Physical-Technical Institute of the National Academy of Sciences of Belarus 220141MinskBelarus

This study presents a novel method using a disk-like sample to assess the workability of metal during the cross wedge rolling(CWR)*** this method,we can quantitatively evaluate the moment destruction which occurs at the center of the sample during *** this study,45 steel was selected to demonstrate the proposed ***,we designed a model for the tools and sample,conducted finite element simulations to analyze the distribution regulations of metal flow,stress,and strain,and evaluated the relationship between the damage and moving distance of the tool during the forming ***,we obtained the optimal deformation temperature range,rolling speed,and geometry parameters for the ***,experiments were conducted from 20℃ to 1200℃ to verify the accuracy of the developed *** was demonstrated that the model was significantly accurate in accessing the workability of 45 steel in the CWR *** proposed method could be generalized to investigate the CWR process for other materials,such as aluminum alloys,superalloys,titanium alloys,etc.

关键词： Cross wedge rolling(CWR) 45 steel Workability Damage Finite element simulation

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