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Evaluation of Process Capability in Gas Carburizing Process to Achieve Quality through Limit Design Concept

材料热处理学报 2004年第5期25卷 395-397页

作者： K. Palaniradja N. Alagumurthi V. Soundararajan Department of mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Steel is the most important metallic material used in industry. This is because of the versatility of its engineering properties under different conditions. In one condition it can be very mild, soft and suitable for any forming operation. In another condition the same steel can be very hard and strong. This versatility is made possible by the different heat treatments that the steel can be subject to. One such treatment is Gas carburizing. This is the most widely used process for surface hardening of low carbon steels. In this method the surface composition of the steel changes by diffusion of carbon and or nitrogen and result in hard outer surface with good wear resistance properties. A striking feature of Gas Carburizing process is that in this process the original toughness and ductility remains unaffected even after heat treatment. 3% nickel chromium case hardened low carbon steels are widely used for critical automotive and machine applications such as rack and pinion, gears, camshaft, valve rocker shafts and axles which requires high fatigue resistance. Fatigue behaviour of case carburized parts depends to a great extent on the correct combination of Hardness Penetration Depth (HPD) and the magnitude of hardness at the surface and beneath the surface with low size and shape distortion. In order to reduce the manufacturing costs in terms of material consumption and elimination of the number of processing steps, the effect of Gas carburizing parameters on the fatigue behaviour should already be considered in the parameter design stage. Therefore it is of importance to optimize the gas carburizing process variables to attain quality products with respect to hardness and case depth. In the present paper, the evaluation of process capability was carried out through a Limit Design Concept called orthogonal array design of experiment. To optimize the process variables the influence of several parameters (Holding time, Carbon potential, Furnace temperature and Quench

关键词：气体渗碳最优化碳势存放时间消火时间炉温

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Study on Surface Engineering of Normalized Steels Subjected To Machine Hardening

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材料热处理学报 2004年第05B期25卷 1329-1332页

作者： N.Alagurmurthi K.Palaniradja V.Soundararajan Department of mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Engineering the surfaces of components to improve the life and performance of parts used in automotive and aerospace engineering is the active area of research. Suitable Thermal/ mechanical/Thermo mechanical surface engineering treatments will produce extensive rearrangement of atoms in metals and alloys and corresponding marked variations in Physical, Chemical and mechanical properties. Among the more important of these treatments are heat treatment processes such as hardening by Quenching, Induction hardening and Case Carburizing which rely on phase transformations to produce desired changes in mechanical properties. Other processes where phase transformation occur are casting, welding and machining etc. [1] Phase transformation may be homogeneous or heterogeneous. Homogeneous involves rearrangements in the structure of the material taking place simultaneously in all parts of the solid, while the heterogeneous transformation involves structural changes which are more localized. Alternatively they could be called as Isothermal and Nonisothermal transformation. But irrespective of the classification, these transformations alter the structure of the material giving rise to changes in the mechanical and physical properties of the processed material. It is of interest to review some consequences of surface modification in isothermal (Normalizing) and nonisothermal transformations (Machining) of low carbon steels.

关键词：正火钢研磨硬化比能能量区别速率

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Analysis on Phase Transformation (ATP) Using Computational Thermal Principles (CTP)

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材料热处理学报 2004年第05B期25卷 716-719页

Computer analysis based on computational thermal principles to predict the transformation kinetics in steels at varying temperatures is of great practical importance in different areas of heat treatment. As a result, using the theory of transient state heat conduction with convective boundary conditions, an efficient program named "ATP" (Analysis on Phase Transformation) has been developed to determine the temperature distribution under different quenching conditions for different geometries such as plate, cylinder and sphere. In addition to these the microstructures and the corresponding hardness developed during quenching are predicted using Time Temperature Transformation (TTT) diagram incorporated in the analysis. To approve our work, dilation curves, Heisler charts and time-temperature history curve have been generated. This paper deals with basic objective of the program (ATP) determination of temperature, microstructure and hardness distribution and also includes an online prediction of austenite-pearlite and austenite-martensite transformation in steels along with the corresponding retained fractions. The quenching of a cylinder in gases, liquids and liquid metals is analyzed to show the non-liner effect of cylinder diameter on the temperature and microstructures. Further in the program we have considered a typical 1080 steel cylinders quenched in water for predicting and comparing the program results with experimental values and can be extended even to other grades of steels. The numerical results of program are found to be in good agreement with the experimental data obtained. Finally the quenching process analysis described in the study appears to be a promising tool for the design of heat-treatment process parameters for steels.

关键词：热处理相位变换 ATP 温度分布冷却曲线 CTP

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Highlights from the literature on risk assessment techniques adopted in the mining industry:A review of past contributions,recent developments and future scope

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International Journal of Mining Science and Technology 2016年第4期26卷 691-702页

作者： Verma Shikha Chaudhari Sharad Department of mechanical Engineering YCCE CollegeRTMNU Department of mechanical Engineering YCCE College

In this paper a comprehensive review is presented of risk assessment techniques adopted in the mining industry worldwide;those techniques applied in other hazardous industries and potential techniques which are robust,mature and holistic and can be implemented for the Indian mining industry in future to enhance workplace safety are also *** from the review are indicative of the fact that socio-technical complexity of industrial systems has *** developments in the area of risk management highlight the need for implementation of the latest robust techniques of risk assessment in the mining *** consideration of the present scenario,the development of a model for risk analysis having an interface between hazard identification and risk assessment,along with an interface between risk assessment and accident causation to predict if an accident will occur under given conditions,has become dire *** will increase hazard awareness and enable mine management to select and prioritize problem areas and identify safety system weaknesses in both underground and surface *** will ultimately help decision makers,risk analysts and safety managers make a major contribution in the development of workplace safety with a near-to-zero accident rate.

关键词： Risk Risk assessment Mining HazardSafety

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On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

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材料热处理学报 2004年第5期25卷 531-535页

作者： V.Soundararajan N.Alagurmurthi K.Palaniradja Department of mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates. Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching. Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load, speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified (Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -II hardening was followed by quenching was carried out as said in Part-1 and the hardened specimen were quenched in liquid Nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, MnO.4% and the rest Iron)

关键词： AISI1095钢液态氮低温淬火抗磨损性

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Cloud Neural Fuzzy PID Hybrid Integrated Algorithm of Flatness Control

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Journal of Iron and Steel Research International 2014年第6期21卷 559-564页

作者： Chun-yu JIA Tao BAI Xiu-ying SHAN Fa-jun CUI Sheng-jie XU college of mechanical Engineering Yanshan University Department of mechanical Engineering Chengde Petroleum College

In connection with the characteristics of multi-disturbance and nonlinearity of a system for flatness control in cold rolling process, a new intelligent PID control algorithm was proposed based on a cloud model, neural network and fuzzy integration. By indeterminacy artificial intelligence, the problem of fixing the membership functions of input variables and fuzzy rules was solved in an actual fuzzy system and the nonlinear mapping between variables was implemented by neural network. The algorithm has the adaptive learning ability of neural network and the indetermi- nacy of a cloud model in processing knowledge, which makes the fuzzy system have more persuasion in the process of knowledge inference, realizing the online adaptive regulation of PID parameters and avoiding the defects of the traditional PID controller. Simulation results show that the algorithm is simple, fast and robust with good control performance and application value.

关键词： flatness control cloud model neural network fuzzy inference PID

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Optimization of Line Configuration and Balancing for Flexible Machining Lines

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Chinese Journal of mechanical Engineering 2016年第3期29卷 579-587页

作者： LIU Xuemei LI Aiping CHEN Zurui college of mechanical Engineering Tongji University

Line configuration and balancing is to select the type of line and allot a given set of operations as well as machines to a sequence of workstations to realize high-efficiency production. Most of the current researches for machining line configuration and balancing problems are related to dedicated transfer lines with dedicated machine workstations. With growing trends towards great product variety and fluctuations in market demand, dedicated transfer lines are being replaced with flexible machining line composed of identical CNC machines. This paper deals with the line configuration and balancing problem for flexible machining lines. The objective is to assign operations to workstations and find the sequence of execution, specify the number of machines in each workstation while minimizing the line cycle time and total number of machines. This problem is subject to precedence, clustering, accessibility and capacity constraints among the features, operations, setups and workstations. The mathematical model and heuristic algorithm based on feature group strategy and polychromatic sets theory are presented to find an optimal solution. The feature group strategy and polychromatic sets theory are used to establish constraint model. A heuristic operations sequencing and assignment algorithm is given. An industrial case study is carried out, and multiple optimal solutions in different line configurations are obtained. The case studying results show that the solutions with shorter cycle time and higher line balancing rate demonstrate the feasibility and effectiveness of the proposed algorithm. This research proposes a heuristic line configuration and balancing algorithm based on feature group strategy and polychromatic sets theory which is able to provide better solutions while achieving an improvement in computing time.

关键词： flexible machining line line balancing line configuration constraints model optimization

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Research of Mechanism of Inductive Maglev Spherical Driving Joint

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Chinese Journal of Electronics 2016年第1期25卷 26-32页

作者： ZENG Li CHEN Qiuyue ZHANG Xiaohong college of mechanical Engineering Yangzhou University

The multi-degree-of-freedom inductive spherical driving joint owns high mechanical integrity and has advantages such as control and trajectory *** of its limit of rotor pose, instant stepping angle and inability to spin around any axis through center of sphere, the suspension and rotation precision of spherical reluctance driving joint isn't high and the response speed can't reach the best. Based on mechanism of rotation and suspension, due to distribution of air gap magnetic induction intensity, a novel inductive maglev spherical driving joint was presented, and electromagnetic suspending force and electromagnetic torque were established. Analyze the magnetic induction intensity, electromagnetic suspending force and electromagnetic torque through finite element simulation, build a bench test of maglev spherical driving joint, and do testing research on displacement characters and suspension and rotation characters of joint rotor.

关键词： Magnetic levitation spherical reluctance driving joint Displacement character Suspending force character Electromagnetic torque character

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Microstructure evolution of components of ZAlSi8Cu3Fe alloy in processing of thixo-diecasting

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中国有色金属学会会刊：英文版 2008年第1期18卷 109-115页

作者：王开刘昌明邹茂华韩兆堂 college of mechanical Engineering Chongqing University

The microstructures of components of ZAlSi8Cu3Fe alloy in the process of thixo-diecasting were *** effects of processing conditions on the microstructure of the alloy in the thixo-diecasting procedures of original casting billets,remelting billets and casting components were researched,and the morphological evolution of α-particles in the alloy was analyzed *** results show that,the microstructure of the original billets poured at 582 ℃ consists of rosette-like primary α-particles;in the procedure of remelting,when the temperature rises over solidus,arms in the rosette-like α-particles begin to fuse off from dendritic branches and after further heating,α-particles surrounded by liquid phase are refined by the diffusion of atoms and rounded owing to the least interface stress and interface energy principles;and in the procedure of thixo-diecasting,the morphologic characteristics of α-particles and the distribution of phases in the structure change greatly for the high shear rate under the restricted area of the ingate.

关键词： ZAlSi8Cu3Fe合金显微结构压铸技术金属学

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Effect of a Carbon Fibre-steel Fibre-graphite Conductive Filler on the Electrothermal Properties of Cementitious Materials

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 141-151页

作者： FAN Yanan WEI Hong ZHENG Hongyong DU Hongxiu Department of Architecture and Environmental Engineering Taiyuan UniversityTaiyuan 030032China college of Civil Engineering Taiyuan University of TechnologyTaiyuan 030032China

Carbon fibre,steel fibre and graphite were used as conductive fillers to prepare cementitious materials with excellent electrothermal *** electrically conductive cementitious materials with different volume dosages were analysed through compressive and flexural strength,electrochemical impedance spectroscopy and temperature rise *** equivalent circuit model was established to study the electrically conductive heat generation mechanism in the electrically conductive cementitious *** results indicate that the mechanical properties of cementitious composite materials with a ternary conductive phase are better than those of pristine cementitious materials because the fibrous filler improves their mechanical ***,the incorporation of graphite in the material reduces its *** fibrous and point-like conductive phase materials into the cementitious material enhances the overall conductive pathway and considerably reduces the electrical resistance of the cementitious material,enhancing its conductive *** volume ratios of carbon fibre,steel fibre and graphite that achieve an optimal complex doping in the cementitious material were 0.35%,0.6%and 6%,*** was determined using the mutation point of each circuit element parameter as the percolation *** addition,at a certain safety voltage,there is a uniform change between the internal and surface temperatures of the conductive cementitious material,and the heating effect in this materialis is considerably better than that in the pristine cementitious material.

关键词： cementitious composites conductive fillers electrothermal properties electrochemical impedance spectroscopy

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