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Hydrogen and Neutron Irradiation Induced hardening in Vanadium Alloys

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中国核科技报告 2002年 943-948页

作者： CHEN Jiming

It is well known that vanadium alloy will face to strong neutron irradiation and hydrogen environments as a structural material in a fusion reactor. Some researches have reported that vanadium alloy took strongly hardening after an exposure to hydrogen environment and irradiation by neutron at a temperature lower than 400 ℃[1 -3]. The ductility of the alloy was lost largely, even entirely brittle fracture

关键词： Vanadium alloy hardening Hydrogen and neutron irradiation

ANN Based Model for Estimation of Transformation hardening of AISI 4340 Steel Plate Heat-Treated by Laser

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Materials Sciences and Applications 2015年第11期6卷 978-994页

作者： Guillaume Billaud Abderazzak El Ouafi Noureddine Barka Mathematics Computer Science and Engineering Department University of Quebec at Rimouski Rimouski Canada

Quality assessment and prediction becomes one of the most critical requirements for improving reliability, efficiency and safety of laser surface transformation hardening process (LSTHP). Accurate and efficient model to perform non-destructive quality estimation is an essential part of the assessment. This paper presents a structured and comprehensive approach developed to design an effective artificial neural network (ANN) based model for quality estimation and prediction in LSTHP using a commercial 3 kW Nd:Yag laser. The proposed approach examines laser hardening parameters and conditions known to have an influence on performance characteristics of hardened surface such as hardened bead width (HBW) and hardened depth (HD) and builds a quality prediction model step by step. The modeling procedure begins by examining, through a structured experimental investigations and exhaustive 3D finite element method simulation efforts, the relationships between laser hardening parameters and characteristics of hardened surface and their sensitivity to the process conditions. Using these results and various statistical tools, different quality prediction models are developed and evaluated. The results demonstrate that the ANN based assessment and prediction proposed approach can effectively lead to a consistent model able to accurately and reliably provide an appropriate prediction of hardened surface characteristics under variable hardening parameters and conditions.

关键词： Laser hardening Process AISI 4340 Steel Case Depth Hardened Bead Width Artificial Neural Network

Nonlinear Model of Image Noise: An Application on Computed Tomography including Beam hardening and Image Processing Algorithms

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Applied Mathematics 2014年第8期5卷 1240-1251页

作者： Rafael Miller-Clemente Marlen Perez Diaz Larisa Zamora Matamoros Sue Edyvean Department of Mathematics and Computing Universidad de Oriente Santiago de Cuba Cuba Medical Exposure Department Public Health England (PHE) Chilton UK Radiation Medical Physics Group Centre of Medical Biophysics Universidadde Oriente Santiago de Cuba Cuba Universidad Central Marta Abreu Santa Clara Cuba

This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the new-born. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.

关键词： CT Nonlinear Noise Model Beam hardening Effect Image Processing Filters Effect

The Effect of Heat Treatment Atmosphere on hardening of Surface Region of H13 Tool Steel

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Journal of Materials Science and Chemical Engineering 2013年第6期1卷 20-29页

作者： Timotius Pasang Zhan Chen Maziar Ramezani Thomas Neitzert Dominique Au Department of Mechanical Engineering Auckland University of Technology Auckland New Zealand

The main objective of the die heat treatment is to enhance the surface hardness and wear properties to extend the die service life. In this paper, a series of heat treatment experiments were conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied and although each heat treatment condition resulted in a different hardness profile, it did not affect the results for gas nitriding. All samples subjected to the nitriding process produced similar thicknesses of hardened case layer with average hardness of 70 - 72 HRC if the initial carbon content is not too low. It was shown that heat treatment without atmospheric control results in a lower hardness on the surface since the material was subjected to decarburization effect. The stainless steel foil wrapping around the sample and heat treatment in a vacuum furnace could restrict the decarburization process, while pack carburization heat treatment resulted in a carburization effect on the material.

关键词： Carburization H13 Tool Steel hardening Heat Treatment Atmosphere Nitriding

Electrolytic surface hardening of steel, cast iron and aluminium-bronze

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China Foundry 2006年第3期3卷 184-189页

作者： Suhas Keshav Paknikar National Centre for Technical Services Pune India

Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel, cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

关键词： electrolytic hardening process variables, S. G. iron, steel, aluminum-bronze

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Properties of Rapid hardening Controlled Low Strength Material Made of Recycled Fine Aggregate from Urban Red Brick Construction Waste

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World Journal of Engineering and Technology 2017年第2期5卷 188-197页

作者： Jin Ran Jinxi Zhang Beijing Key Laboratory of Traffic Engineering Beijing University of Technology Beijing China Key Laboratory of Expressway Maintenance Technology of Ministry of Transport (Jinan) Jinan China

In some cases of emergency backfill engineering projects, traditional backfill materials cannot meet the requirements of fast construction due to their long curing time. This study presents a new kind of rapid hardening controlled low strength material, which utilizes both rapid hardening sulphoaluminate cement and recycled fine aggregate from urban red brick construction waste. Totally, sixteen mixtures were prepared for the experiment with different cement-to-sand ratios and water-to-solid ratios. The flowability and bleeding rate of fresh mixture were measured to evaluate its workability, and the compressive strength of hardened mixture was tested to evaluate its rapid hardening and mechanical properties. Test results indicate that rapid hardening controlled low strength material containing recycled fine aggregate from urban red brick construction waste can achieve the desirable flowability, but the bleeding rate increases with the increase of flowability. In addition, 2-hour compressive strength can reach 0.08 - 0.12 MPa, and 4-hour compressive strength is 0.32 - 1.54 MPa, which can meet the requirements of emergency backfill construction. At last, based on the derived compressive strength, a fitting model for predicting compressive strength evolution of this new rapid hardening backfill material is developed, which fits accurately with these experimental data.

关键词： Controlled Low Strength Material Rapid hardening Sulphoaluminate Cement Recycled Fine Aggregate Construction Waste Urban Red Brick Workability Compressive Strength

STUDY OF THE THERMODYNAMICS DURING THE HYDRATION AND hardening OF ANHYDRITE

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Journal of Wuhan University of Technology(Materials Science) 1989年第1期4卷 27-35页

作者：岳文海赵青南

The process of hydration and hardening of the anhydrite,and the condition of practical use of its products have been studied by way of the thermodyna- mic calculation.The calculated results show that the hydration reaction of anhydrite is a spontaneous process and follows the dissolution-crystallization mechanism it is also shown that the drying-curing temperature of the anhydrite products can not be higher than 85℃ and the temperature of practical use of its products can't be higher than 48℃ under the moist environment.

关键词： Anhydrite Hydration hardening Thermodynamics

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Laser Surface hardening of Tool Steels—Experimental and Numerical Analysis

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Journal of Surface Engineered Materials and Advanced Technology 2013年第2期3卷 146-153页

作者： Abdel-Monem El-Batahgy Ramadan Ahmed Ramadan Abdel-Rahman Moussa Manufacturing Technology Department Central Metallurgical R & D Institute Cairo Egypt Mechanical Engineering Department Faculty of Engineering Helwan University Helwan Egypt. Spare Parts Sector Egyptian Iron and Steel Company Helwan Egypt

This research work is focused on both experimental and numerical analysis of laser surface hardening of AISI M2 high speed tool steel. Experimental analysis aims at clarifying effect of different laser processing parameters on properties and performance of laser surface treated specimens. Numerical analysis is concerned with analytical approaches that provide efficient tools for estimation of surface temperature, surface hardness and hardened depth as a function of laser surface hardening parameters. Results indicated that optimization of laser processing parameters including laser power, laser spot size and processing speed combination is of considerable importance for achieving maximum surface hardness and deepest hardened zone. In this concern, higher laser power, larger spot size and lower processing speed are more efficient. Hardened zone with 1.25 mm depth and 996 HV surface hardness was obtained using 1800 W laser power, 4 mm laser spot size and 0.5 m/min laser processing speed. The obtained maximum hardness of laser surface treated specimen is 23% higher than that of conventionally heat treated specimen. This in turn has resulted in 30% increase in wear resistance of laser surface treated specimen. Numerical analysis has been carried out for calculation of temperature gradient and cooling rate based on Ashby and Easterling equations. Then, surface hardness and hardened depth have been numerically estimated based on available Design-Expert software. Numerical results indicated that cooling rate of laser surface treated specimen is high enough to be beyond the nose of the CCT diagram of the used steel that in turn resulted in a hard/martensitic structure. Numerically estimated values of surface temperature, surface hardness and hardened depth as a function of laser processing parameters are in a good agreement with experimental results. Laser processing charts indicating expected values of surface temperature, surface hardness and hardened depth as a function of different wider range of laser processing par

关键词： High Speed Tool Steels Laser Surface hardening Ashby and Easterling Heat Transfer Equations Design Expert Software Laser Processing Charts

Calculation of Temperature Field During Laser Transformation hardening of Cylindrical Bodies

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Journal of Shanghai Jiaotong university(Science) 2000年第1期5卷 72-75页

作者： Liwen Zhang, Lixia Wei Guoliang Zhang, J. Th.MDe Hosson Yuanliang Xia , Fugang Wang 1.The State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams 2.Material Engineering Department of Dalian University of Technology, Dalian 11 60

A Two-dimensional transient heat transfer model for laser transformation hardening process of cylindrical bodies has been developed. The surface heat loss of the sample, the latent heat of phase transformation, and the temperature dependence of thermal properties of material were considered. The laser heat source was considered as a moving Gaussian heat flux with a constant velocity. Finite element method was used to calculate the transient temperature field. A program to calculate the temperature field was developed using FORTRAN language. The transient temperature field, the width and depth of laser transformation hardening zone of 42CrMo steel sample during laser transformation hardening process was calculated. The widths and depths of laser transformation hardening zones of 42CrMo steel samples were also measured experimentally. The calculated widths and depths of laser transformation hardening zones are in good agreement with the experimental results.

关键词： Laser Transformation hardening Temperature Field Cylindrical Body

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