bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability Based Design Optimization Framework for Boat Propeller
Authors: Makhloufi A. , Mansouri M. , Radi Bouchaib , El Hami Abdelkhalak
Published: April 2015

The need for improvements in engineering designs especially for coupled structures is nowadays becoming a major industry request. Today there is a desire to perform optimizations in order to receive optimal system properties. However, for computationally expensive simulation models, an optimization may be too tedious to be motivated. Deterministic approaches are unable to take into account all the variability’s that characterize design input properties without leading to oversized structures. The objectives of this work are to quantify the influence of material and operational uncertainties on the performance of structures coupled with fluid, and to develop a reliability-based design and optimization methodology for this type of the structures. Such a problem requires a very high computation cost, which is mainly due to the calculation of gradients, especially when a finite element model is used. To simplify the optimization problem and to find at least a local optimum solution, a new method based on semi-numerical solution is proposed in this paper. The results demonstrate the viability of the proposed reliability-based design and optimization methodology relative to the classical methods, and demonstrate that a probabilistic approach is more appropriate than a deterministic approach for the design and optimization of structures coupled with fluid
Effect of Plasma Gases on the Structure and Properties of WC-CrC-Ni Coatings
Authors: Richert Maria , Nejman Ilona , Poręba Marek , Sieniawski Jan , Kuczek Łukasz
Published: April 2015

The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coatings deposited at the graphite substrate has been investigated. The coatings were deposited by plasma spraying method in equipment Cham Pro –Thermal Spray Systems produced by Sulzer company. The microstructure of coatings were investigated by light microscopy (MO) and scanning electron microscopy (SEM). The performed investigations have been shown that with the increasing of amounts of argon and reducing volumes of helium and nitrogen, the microhardnees increased. The plasma gases also influenced on the porosity of coatings. Keywords: WC-CrC-Ni coatings, plasma spraying, microstructure, porosity Acknowledgement: The work was supported by project No INNOTECH – K2/IN2/9/181851/NCBR/13
The Possibility of Deposition of Diamond and DLC Coatings by PACVD Method
Authors: Poręba Marek , Zawadzka Paulina , Richert Maria , Sieniawski Jan , Strączek Tomasz , Kapusta Czesław
Published: April 2015

The Diamond like carbon (DLC) and diamond coatings were deposited on a steel substrate using plasma assisted chemical vapor deposition (PA CVD) method. The parameters of deposition were analyzed in relation to the effectiveness of the process and the quality of coatings. It was found that the DLC coatings formed only at specific conditions of temperature and pressure of precursor gases. The characterization of coatings were performed by Raman spectromicroscopy, X-ray diffraction and infrared spectromicroscopy which allowed us to recognize the dominant phases and the distribution of bonds inside the coatings. The chemical bonds such as sp2 C-C, sp3 CH3/CH2 and sp3 CH were found in microstructure coatings. The maps of distribution of bonds in the coatings were also prepared. Additionally, their microstructure was investigated by scanning electron microscopes which have revealed a spherical grains morphology of the coatings.
Characteristics of the G200CrNiMo4-3-3 Cast Steel in as Cast State
Authors: Rożniata Edyta , Krawczyk Janusz , Dąbrowski Robert , Pacyna Jerzy
Published: April 2015

The subject of investigations constituted the G200CrNiMo4-3-3 cast steel applied for metallurgical rolls. This is the material, which microstructure can be modified by the heat treatment. The presented hereby work concerns the initial state (as cast condition) of the investigated cast steel. This cast steel constitutes the initial material for the heat treatment. The morphology of carbide precipitates, including the cementite precipitated on grain boundaries of the primary austenite, hypereutectoid cementite precipitated in the Widmannstӓtten system and lederburitic cementite, were characterised in the study. The results of investigations of mechanical and fractographic properties of the G200CrNiMo4-3-3 cast steel, were also presented. Among others, the values of fracture work in the impact test, fracture toughness (KIc) and wear resistance were given. The crack pathway together with the hypereutectoid cementite fraction role in its development, was presented. The obtained investigation results, presented in the hereby paper, will constitute the comparison base for the assessment of the heat treatment influence on the microstructure and properties of the tested G200CrNiMo4-3-3 cast steel.
Surface Tension in a Cu-Pb-Fe Liquid Alloy (XCu=0.9)/Al2O3/Gaseous Phase System
Authors: Sak Tomasz , Pietrzyk Stanisław
Published: April 2015

The surface tension of the liquid ternary Cu-Pb-Fe alloys at the constant content of copper (XCu=0.9)-refractory material Al2O3-gaseous phase was determined. The experiments were performed in the range of temperature between 1100 and 1350 °C at the different content of lead and iron (XFe/XPb+XFe). The surface tension was determined by sessile drop method. The composition of the investigated alloys corresponds to the composition of the Cu-Pb-Fe alloys obtained via the reduction of the slag obtained during the direct-to-blister flash smelting process in an electric furnace. Images of the liquid drops were made using the X-ray technique and the surface tension values were calculated using the corresponding software programs.
An Analytical Model for the High Temperature Low Sag Conductor Knee Point Determination
Authors: Mamala Andrzej , Knych Tadeusz , Smyrak Beata , Kwaśniewski Paweł , Kiesiewicz Grzegorz , Jabłoński Michał , Ściężor Wojciech
Published: April 2015

The modern high voltage power overhead lines operate with high temperature low sag (HTLS) conductors due to possibility of the current capacity increase. HTLS conductors are material and technological advanced solutions. The main advantage of HTLS conductors is a special designed operation conditions which cause the transformation of tensile stresses from the external aluminium base layers to the core. The conditions of this transformation are called “knee point” because a rapid change of the conductor sag - temperature relationship is observed. Prediction of conditions of the “knee point” temperature (KPT) is a key problem during overhead line design. The KPT is a function of different factors like conductor materials properties, conductor design, span parameters, sagging procedures and overhead line exploitation conditions. The paper presents an original theoretical model for HTLS conductors KPT calculations and shows some examples and comparisons of the different conductor designs and parameters.
Influence of Severe Plastic Deformation Induced by HE and ECAP on the Thermo-Physical Properties of Metals
Authors: Skiba Jacek , Dominiak Adam , Wiśniewski Tomasz S. , Pachla Wacek , Kulczyk Mariusz , Przybysz Sylwia
Published: April 2015

The study is aimed at comparing the changes which occur in the microstructure and thermo-physical properties of pure copper (99.9%) and when copper alloyed with chromium and zirconium subjected to severe plastic deformation (SPD). The plastic deformation techniques employed were hydrostatic extrusion (HE), equal channel angular pressing (ECAP), and a combination of these two processes. The materials thus obtained had an ultra-fine-grained structure with the thermo-physical properties differing from those of the untreated materials. It appeared that there is a correlation between the deformation method employed and the thermo-physical properties of the materials, such as diffusivity and specific heat.
An Analysis of the Microstructure and Mechanical Properties of Rapidly Solidified Al-1Fe-1Ni-5Mg Alloy
Authors: Kula Anna , Blaz Ludwik , Sugamata Makoto
Published: April 2015

Experiments on Al-1Fe-1Ni-5Mg alloy were performed to determine the effect of rapid solidification (RS) on the material strengthening, which result from the refining of the grain size and intermetallic compounds. Additionally, an enhancement of the material strengthening due to magnesium addition was also observed. RS procedure was performed using spray deposition of the molten alloy on the rotating water-cooled copper roll. As a result, highly refined structure of rapidly solidified flakes was obtained. Using common powder metallurgy (PM) techniques, i.e. cold pressing, vacuum degassing and hot extrusion, as received RS-flakes were consolidated to the bulk PM materials. For comparison purposes, the conventionally cast and hot extruded Al-1Fe-1Ni-5Mg alloy was studied as well. RS process combined with hot pressing and extrusion procedure was found to be very effective method for the manufacture of fine grained material and effective refinement of intermetallic compounds. However some inhomogenity of particles distribution was observed, which was ascribed to varied cooling rate dependent on the particular spray-drop size. Mechanical properties of as-extruded material were examined using compression test at 293K – 873K. High strength and ductility of as-extruded RS material with respect to conventionally produced alloy were observed. However, the effect of enhanced mechanical properties of RS material is observed only at low deformation temperatures. It was found that increasing deformation temperature above 400K results in negligible hardening of RS samples if compared to conventionally produced material.
Experimentally Investigate the Vortex Ferro-Viscosity under Directional Field
Authors: Ho Je Ee , Yen Chen Lung , Lin Jian Xun
Published: April 2015

In this study, apparent ferro-viscosity on applied directional field, through the evaluation of mean piping flow velocity, is examined. Here viscosity in magnetized ferro-flow is found to be closely dependent on the field intensity as well as direction, which is quite different from the constant thermal property usually used in traditional fluid dynamics problem. To predict ferro-magnetization and ferro-viscosity induced under horizontal and vertical field imposed , an auxiliary electromagnetic mechanism is then designed and set up ,As a result, the apparent viscosity ,for ferro-concentration ψ0.4 and 0.04 exposed to field in different direction, will initiate a faster growth within field strength of 6~12 mT where the quick magnetization of ferro-particles starts working, and magnetic field along with flow direction is found to have more potential to induce viscous drag. While compared with theoretic results on Brownian relaxation theory in Langevin function, experimental vortex viscosity behave a good agreement within the working magnetic intensity 0~36 mT and their maximum relative errors will be less than 10% and 50% for ferro-concentration ψ0.4 and 0.04 at working temperature at 25 o c.
The Friction and Wear of Silicon Nitride Ceramic with BSA Lubricant
Authors: Zhou Jing Ling , Zhai Chun Shu , Yang Su Yun , Wu Shu Qian , Wu Guo Qing , Xu Hai Li
Published: April 2015

To research the friction and wear of silicon nitride ceramic with bovine serum albumin lubricant, the tribological properties of silicon nitride ceramic against stainless steel were investigated on CETR UMT-2 under lubrication of bovine serum albumin, deionized water, physiological saline and physiological saline mixed with bovine serum albumin. The worn surfaces of silicon nitride ceramic ball and stainless steel pin were examined with a digital microscope (VHX-2000). The friction coefficients of steady state are 0.26, 0.35, 0.69 and 0.8 under bovine serum albumin, physiological saline mixed with bovine serum albumin, physiological saline and deionized water. The lowest friction coefficient of steady state is 0.26 which is under lubrication of bovine serum albumin. The highest friction coefficient is 0.8 under the lubrication of deionized water. The measured worn areas of silicon nitride ceramic balls are 1282.3μm2, 1898.6μm2, 2753.9μm2 and 3645.7μm2 under bovine serum albumin, physiological saline mixed with bovine serum albumin, physiological saline and deionized water. The smallest worn area of silicon nitride ceramic ball is 1282.3μm2 which is measured under the lubrication of bovine serum albumin. The highest worn area of silicon nitride ceramic ball is 3645.7μm2 which was measured under the lubrication of deionized water. The same wear mechanism of silicon nitride ceramic ball had been found under the lubrication of bovine serum albumin, deionized water, physiological saline and physiological saline mixed with bovine serum albumin. The depth of scratches of worn surface of silicon nitride ceramic ball lubricated with BSA is 3μm which are the shallowest.
Analysis of the Thermo-Mechanical Coupling of Elasto-Plastic Rough Body during Rotating Process
Authors: Chen Jing Jing , Huang Jian Meng , Gao Cheng Hui , Lin Xie Zhao
Published: April 2015

A finite element model is developed to study the transient thermo-mechanical contact between a rough body and a flat body. The model consideres the heat flux coupling, the interaction among adjacent contact asperities and elasto-plastic deformation of the rough body. It is observed that the temperature / contact pressure / stress are coupled and fluctuate obviously when the interaction of contact asperities enhances. The fluctuation of the VonMises equivalent stress makes the equivalent plastic strain of the frictional surface layer accumulate continually which might cause fatigue wear and plastic deformation wear of the material when the frictional rotating process repeated.
Structural, Electrical, and Resistance Force Characteristics of Ga-In-Sn Eutectic Alloys
Authors: Shen Y.F. , Horng Jeng Haur , Wen C.C. , Fang Jau Shiung
Published: April 2015

This work aims at investigating the electrical property and the friction force of Ga-In-Sn eutectic alloys. The performance of the alloys is increasingly needed on conducting lubricant. Resistance force dependence of normal force was examined by atomic force microscopy, and the results showed that Ga65In21Sn14 had the highest friction coefficient of 3.07 and Ga80In13Sn7 had a lowest friction coefficient of 1.46. Electrical resistivity of the studied eutectic alloy was from 25.9 to 27.7 μΩcm at 25°C. Accordingly, the electrical resistivity as a function of temperature revealed a temperature coefficient of ranging from 12.67 ✕10-3 °C-1 to 4.94 ✕10-3 °C-1. High thermally stable and wetting capability make the studied Ga-In-Sn alloys can potentially be used as a conducting lubricant.
Tribology Management and Applications in China Steel
Authors: Huang Yi Sheng
Published: April 2015

Mass amount of equipment and harsh operating condition in steel plants require comprehensive management system, along with lubrication techniques such as lubricating oil quality improvement, used oil monitoring, etc., to ensure proper tribological condition for all mechanical components. In that case, cost management is essential to evaluate the performance of tribology management. This paper is intended to discuss the system establishment, scope of work and actual applications of tribology management in China Steel.
Tribological Characteristics of Amorphous Hydrogenated DLC in the Presence of Commercial Lubricating Oil
Authors: Al Mahmud K.A.H. , Kalam M.A. , Masjuki H.H. , Mobarak H.M.
Published: April 2015

Currently diamond like carbon (DLC) coatings application for automotive components is becoming a favorable strategy to cope with new challenges faced by automotive industries. DLC coating is very effective to lower the coefficient of friction and wear rate, which in turn could improve fuel efficiency and durability of the engine components. Commercially available fully formulated lubricating oils are specially produced to enhance the lubrication of ferrous materials. Therefore, nonferrous coating (DLC) interaction with commercial lubricating oil needs to be investigated. In this current investigation, coefficient of friction and wear rate were investigated by ball on plate tribo testing machine at different temperatures in the presence of SAE 40 lubricating oil. At high test temperature coefficient of friction decreases, however wear rate increases for the a-C:H coated plate, however, steel/steel contact shows opposite trend of coefficient of friction and wear rate change.
Ball Screw Device Applied to Heavy Loading Condition
Authors: Tsai Shang Hua , Hwang Yih Chyun , Kang Chao Yuan , Chen Hui Chen
Published: April 2015

With the rising of public environmental awareness and energy saving goal, high efficient transmission of ballscrew is widely used for production equipment. Of all the ballscrew application, heavy loading is the most stringent operation condition. The crucial techniques for this application are ball recirculation system and lubrication design. In this article, a heavy-load type ballscrew is verified to meet the application requirements through experiments, dynamic simulations and test runs on test bench.
Feasibility Study of Micro-Hole Wall Grinding by Micro-Elastic Abrasive Particles
Authors: Tsai Feng Che , Yang Shie Chen , Mao Tsuo Fei , Huang Hsi Chuan , Li Tsung Lun
Published: April 2015

This study aims to develop a polishing process improvement technology for deep micro-hole knockout hole wall with high aspect ratio, and discuss the optimal polishing parameter combination of abrasive jet machining method and micro-elastic abrasive particles for deep micro-hole knockout hole wall surface. A micro-elastic abrasive process technology was thus developed. The experimental results showed that the micro-elastic abrasive has better grinding effect on the surface roughness of knockout hole wall in length of 300 mm and in inside diameter of ψ2mm in the machining conditions of jet pressure 0.5MPa, volume mixing ratio 2:1 of abrasive particles to additive and vacuum attraction 70 cmHg. It was improved from 2.39 μm Ra (10.74 μm Rmax) to 0.08 μmRa (1.12 μm Rmax), proving the feasibility of micro-elastic abrasive. The surface was improved well, and the process time was shortened greatly.
The Surface Parameters Analysis of Magnesium Alloys Sheet during Warm Isothermal Forming
Authors: Yang Tung Sheng , Yang Z.X. , Chang Sheng Yi
Published: April 2015

This study uses the finite element method (FEM) to predict the workpiece surface parameters, including contact area ratio and surface roughness, of asperity flattening in indentation and sliding contact for magnesium alloys sheet during warm isothermal forming. Contact area ratio and surface roughness are investigated for different process and material parameters, such as sliding distance, temperature, normal pressure and bulk strain rate by finite element analysis. The predicted results of the surface parameters from the finite element analysis are in good agreement with the results obtained from experiments.
Dynamic Frictions between AISI 316L and 3MTM TrizactTM Structured Abrasive Belts during Mirror-Like Polishing
Authors: Yang Bo Sung , Yeh Jin Cheng , Tsai Ming Shin , Liao Jing Lun , Wu Shun Yi , Hsu Jar How , Tsai Hsi Hsun
Published: April 2015

polishing is an essential process for deriving of the mirror-like surface of the AISI 316L stainless steel to minimize the surface roughness. Sliding, plowing and cutting, the fundamental mechanisms of abrasive machining, are occurred during the polishing and then would decrease the roughness on the surface. By 3MTM TrizactTM structured abrasive belts, the previous stainless steel are polished. Pyramid arrays containing the abrasives and epoxy formed on the belt give the abrasive machining. The glass transition and degradation temperatures of epoxy are about 150 and 250 degrees, respectively. The friction coefficient between the AISI 316L workpiece and 3MTM TrizactTM structured abrasive belt under different rotational speed may affect the polishing efficiency and the cost. The mechanism of the abrasive machining includes the sliding, plowing and cutting while the previous two are preferred during polishing. By 3MTM TrizactTM Structured Abrasive belts, the grit sizes are #800 and #2000, the MIM stainless steel cases are polished. The contact dynamic friction coefficient induces a higher specific polishing energy, the polishing temperature is thus increased. Deriving the friction coefficient is therefore important for stainless steel polishing. Experimental results indicate that the dynamic friction coefficient decreases respect to the rotational speed and the press-on force of workpiece. The coefficients of friction of all the workpieces under different tangential velocity are in a large range of 1.2–5.6, but the friction coefficient of the tangential velocity of 23.56 m/sec shows slightly variation even press-on force in 5 Newtons or in 20 Newtons.
Surface Roughness Effects on Fluid Flow between Two Rotating Cylinders
Authors: Srirattayawong Sutthinan , Gao Shian
Published: April 2015

In general, the thin fluid film problems are explained by the classical Reynolds equation, but this approach has some limitations. To overcome them, the method of Computational Fluid Dynamics (CFD) is used in this study, as an alternative to solving the Reynolds equation. The characteristics of the two cylinders contact with real surface roughness are investigated. The CFD model has been used to simulate the behavior of the fluid flows at the conjunction between two different radius cylinders. The non-Newtonian fluid is employed to calculate the lubricant viscosity, and the thermal effect is also considered in the evaluation of the lubricant properties. The pressure distributions, the fluid film thickness and the temperature distributions are investigated. The obtained results show clearly the significance of the surface roughness on the lubricant flow at the contact center area. The fluctuated flow also affects the pressure distribution, the temperature and the lubricant viscosity in a similar pattern to the rough surface profile. The surface roughness effect will decrease when the film thickness is increased.
Effects of the Ultra-Dispersed Nano-Diamond Additive on the Grease Boundary Lubrication Performance in the Reciprocating Journal Bearing Test
Authors: Hsieh Hung Tai , Chen Guan Lin , Tsai Ping Hsueh , Chu Hsiao Yeh
Published: April 2015

This study analyzes the tribological performance of the test results of the journal bearing wear tester designed for the simulation of the toggle pin motion in the plastics injection molding machine. Grease with or without the addition of ultra-dispersed nanodiamond (UDD) particles were all tested in the durability tests. It showed that the grease with UDD additive could effectively extend the life of grease more than twice as long as the grease life without UDD additive in the reciprocating heavy-load and low-speed journal bearing tests.
Atomistic and Finite Element Contact Analysis of an Asperity and a Rigid Flat
Authors: Tan Chung Ming , Lin Chao Ming , Tsai Hung Jung
Published: April 2015

The elastic-plastic finite element and atomistic models for the frictionless contact of a deformable sphere pressed by a rigid flat is presented. The evolution of the elastic-plastic contact with increasing interference is analyzed using two different analysis tools. The simulation results show that deformation mechanisms revealed in the two different analysis tools are quite different from each other. The physical phenomena “jump-to-contact” and “force drops during dislocation emission” are observed in our atomistic simulations which can not be seen in the continuum analysis.
Numerical Analysis of Annular Seal with Different Distribution of Surface Texture
Authors: Guo An Nan , Wang Xiao Jing , Gang Shen , Jiang Deng Feng
Published: April 2015

Surface texturing has been shown to reduce friction and increase the film thickness in various tribological applications (hydrodynamic bearings, mechanical seals, and cylinder-liner contacts). Studies have reported that surface-texture can reduce the resistance of sliding friction pair, increase the oil film thickness, increase the bearing’s capacity. Surface texture structure’s design and layout are very important, unfavorable design may lead to be counterproductive. In this paper, in combination with the 650mm seal structure, we are using the main design of groove type to seal the inner surface texture, so as to study the geometry structure and distribution's influence on seal property.
Tribological Characteristics of Silicon Nitride Ceramic in Three Water-Based Lubricants
Authors: Zhou J.L. , Yang Su Yun , Zhai C.S. , Cheng Z.M. , Wu Shu Qian , Wu G.Q.
Published: April 2015

The friction coefficient of tribology pair between silicon nitride ceramic and stainless steel was researched with bovine serum albumin, saline and water lubricants. The coefficient of friction of silicon nitride in bovine serum albumin is lower than those in saline and water. Using digital microscope, the worn surfaces of silicon nitride and stainless steel were viewed. The groove depths of worn stainless steel surface were measured. The depth with bovine serum albumin is shallower than those in saline and water. The results showed that ceramic in bovine serum albumin has good tribological characteristic. This research provides the reference for the development of ceramic artificial joint.
Effect of Alloying Elements and Heating Parameters on the Hardness of Quenched and Tempered Steel 42CrMo after Induction Hardening
Authors: Jiang Bo , Wen Xin Li , Zhou Le Yu , Zhao Min , Zhao Hai Dong , Liu Ya Zheng
Published: April 2015

The effect of alloying elements, heating rate and quenching temperature on the hardness of steel 42CrMo after induction hardening were investigated by thermal simulation tests, hardness tests, optical microscopy (OM) and scanning electronic microscopy (SEM). The steel No.2 was obtained by adding 1.49% Ni and reducing 0.32% Cr in steel No.1. Experimental results show that the hardness of steel No.1 decreases while that of steel No.2 slightly increases under the quenched temperature of 900 °C when the heating rate increases from 100 °C/s to 300 °C/s. When the heating rate is 300 °C/s, the hardness of steel No.1 increases sharply with the elevating of the quenched temperature. However, the hardness of steel No.2 increases gently with the quenched temperature increasing below 900 °C but keeps constant above 900 °C. It is interesting that the hardness of steel No.2 is obviously higher than that of steel No.1 under the same heating process. This phenomenon can be attributed to the following aspects: firstly, the Ac1 and Ac3 temperatures can largely decrease and the dissolution of carbide proceeds further; secondly, the addition of alloying element and the dissolution of carbide in the austenite can improve the hardenability of steel and thus increase the volume percentage of martensite in the quenched microstructure; in addition, the quenched microstructure of steel No.2 is finer than that of steel No.1 which undoubtedly helps the increase of hardness. In consideration the disadvantage of higher quenched temperature and heating rate, it is comprehensive to determine the quenched temperature as 900 °C and heating rate as 100 °C/s in order to increase the hardness of steel No.2.
A Phase-Field Model for Rapid Solidification with Non-Equilibrium Solute Diffusion
Authors: Wang Hai Feng , Lai Cun , Zhang Xiao , Wang Kuang , Liu Feng
Published: April 2015

Since the growth velocity can be comparable with or even larger than the solute diffusion velocity in the bulk phases, modeling of rapid solidification with non-equilibrium solute diffusion becomes quite an important topic. In this paper, an effective mobility approach was proposed to derive the current phase field model (PFM). In contrast with the previous PFMs that were derived by the so-called kinetic energy approach, diffusionless solidification happens not only in the bulk phases but also inside the interface when the growth velocity is equal to the solute diffusion velocity in liquid. A good agreement between the model predictions and experimental results is obtained for rapid solidification of Si-9at.%As alloy.
Effect of Nitrogen Content on Mechanical and Tribological Properties of HfCxNy Films Deposited by Reactive Magnetron Sputtering
Authors: Wang Shuo , Zhang Kan , Guo Xin , Du Su Xuan , Wen Mao , Zheng Wei Tao
Published: April 2015

Based on previous work on lubricant hard HfCxfilm, the HfCxNyfilmswere deposited by sputtering from theHf target in a mixture of discharging N2,Ar and CH4, and the N content in films was accurately controlled by changing the N2flow rate.Theintroduction of N into the films contributed to the presence of solid solution FCC-HfC(N) and FCC-HfNphase appeared at high N content in films. In addition, the a-C content in the filmsdecreasedwith increment ofN content in the films. In comparison with HfCxfilm, hardness of HfCxNyfilms were enhanced from 21 GPa to 25 GPa with N content rising to 6.8 at.% but then surplus N in the films impaired the hardness. The coefficient of friction and surface roughness for HfCxNyfilms increasedfrom 0.10 to 0.23 and 3.13 nm to 12.4 nm, respectively, with decreasing a-C content from 52.9 at.% to 46.3 at.%. However, the introduction of N into HfCxFilm improvedthe wear resistance of filmseffectively, and the specific friction rate for this HfCxNyfilm deposited at 8 sccm N2was only 6.17×10-7mm3/Nm about half of that of HfCxfilm (1.09×10-6mm3/Nm).
Review of Research Progress of Prestressed Treatment to the Thick-Walled Cylindrical Parts
Authors: Lu Zhi Bing , Wang Cheng Yong , Zhang Peng , Zhang Xin Yi
Published: April 2015

The mechanical properties of single layer thick-walled cylinder under the working condition and common failure forms were analyzed, and the results showed that there’s limitation to improve the load supporting capacity only by increasing the wall thickness and the strength of materials. The effective way to improve the stress distribution of single layer thick-walled cylinder is to make the cylinder forced by prestressing. The prestress on the cylinder can counterbalance a portion of the working tensile stress. Firstly, this paper describes the structural of prestressed cylinder of multilayer shrink-on and points out its disadvantage. Secondly, based on the shrink-on cylinder, three kinds of improved cylinder structure of split block shrink-on type, autofrettaged shrink-on type and wire intertwined type are elaborated. The principle, the key technology and the process methods of prestressed processing are parsed. Finally, research directions on the innovative cylinder structure with high load supporting capacity are put forward.
Characterization of Solution Treatment on AA7A55 Alloy
Authors: Lv Xin Yu , Guo Er Jun , Wang Li Juan , Han Xing , Wang Xiang Jie
Published: April 2015

The thermal stability of constituent particles in both as-rolled and solution treated in AA7A55 has been investigated by means of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Three types of solution treatments were used to dissolve particles constituents. Whereas the degree of recrystallization aggravates which deteriorates the properties with increasing the solution temperature, a significant amount of recrystallization exists after utilizing 480°C solution treatment whereas a much smaller extent from 480°C to 490°C. And electrochemical and exfoliation corrosion matched with the degree of recrystallization. With increasing the recrystallization the corrosion become worse.
Effects of Rare Earth on Microstructure and Mechanical Properties of Al-3.2Mg Alloy
Authors: Zhang Xin , Wang Ze Hua , Zhou Ze Hua , Xu Jian Ming , Zhong Zhao Jun , Yuan Huan Long , Wang Guo Wei
Published: April 2015

A series of Al-3.2Mg alloys with addition of 0~1.6 wt.% rare earth (Ce and La) were prepared. The microstructure of as-cast Al-3.2Mg alloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and the tensile strength was measured. The results indicated that the addition of rare earth elements refined grain size and secondary dendrite arm spacing (SDAS), and the tensile strength was affected by means of the second-phase precipitation and the grain boundary. Accordingly, the ductility of Al-3.2Mg alloys reduced with the increasing of RE addition due to the more second-phase formation.
Analysis on the Influencing Factors of Heat Transfer for the Slot Nozzle Convection Impact in Rolled Strip Preposition Ultra-Fast Cooling
Authors: Shi Jian Hui , Yuan Guo , Jiang Lian Yun , Zhao Kun , Wang Guo Dong
Published: April 2015

The aim of this work is to optimize process design parameters of the hot rolling steel strip preposition ultra-fast cooling (UFC) system, and improve the stability and uniformity of micro heat transfer during the high strength cooling process of hot rolling strip. According to the technology and equipment feature of the pre-UFC system for a factory, the convective heat transfer process of single nozzle and strip in UFC system was studied numerically by the fluid-structure interaction finite element method (FEM). The influence of different parameters on the slot impinging jet heat transfer coefficient was obtained, such as jet angle, the jet velocity, the slot nozzle width and water temperature. The results show that on the ultra-fast cooling process of the strip in the initial temperature of 850 °C and thickness of 8 mm, the global average heat transfer coefficient can be increased with the increase of jet velocity, and decrease of the cooling water temperature. The jet angle and the slot nozzle width have minimal effect on it for the whole heat transfer zone. The local average heat transfer coefficient first increased and then decreased with the increase of jet angle and slot nozzle width at the jet impingement location.
Microstructure and Tensile Deformation Behavior of a Hot-Rolled Directly Quenched and Dynamically Partitioned Steel Containing Proeutectoid Ferrite
Authors: Tan Xiao Dong , Xu Yun Bo , Yang Xiao Long , Hu Zhi Ping , Peng Fei , Ju Xiao Wei , Yu Yong Mei , Wu Di
Published: April 2015

Hot-rolling direct quenching and dynamical partitioning (HDQ&DP) processes were applied to a low-carbon steel containing silicon and manganese based on thermo-mechanical control process (TMCP) technology and ultra-fast cooling (UFC) technology. The microstructures and phase compositions were characterized and analyzed using SEM, EBSD, TEM and XRD. The mechanical properties and tensile deformation behaviors were investigated by means of uniaxial tensile test. The microstructures and tensile deformation behaviors of both HDQ&DP steel with and without proeutectoid ferrite were comprehensively expounded by comparing with each other. Results show that the amount of retained austenite in the HDQ&DP steel with proeutectoid ferrite can reach up to 17.3%, which is higher than that in the HDQ&DP steel without proeutectoid ferrite (15.7%). The HDQ&DP steel without proeutectoid ferrite possesses extremely high ultimate tensile strength (UTS) up to 1700 MPa with yield ratio about 0.73 and elongation about 11.5%. The introduction of proeutectoid ferrite can result in a moderate decrease of UTS to 1240-1400 MPa, a drastic decrease of yield ratio to 0.51-0.69 and a certain increase of elongation to 13.0-13.7%. The existence of the proeutectoid ferrite can partly enhance the work hardening ability of the steel and may improve its formability. It is concluded that the HDQ&DP steel with relatively large amount of proeutectoid ferrite and certain amount of bainite has extensive application prospects.
Recovery and Recrystallization Behavior of Large Sized β Phase Grains in TC18 Titanium Alloy during Annealing Process
Authors: Yan Meng Qi , Sha Ai Xue , Zhang Wang Feng , Wang Yu Hui
Published: April 2015

The manufacturing processes of TC18 titanium alloy bar takes about 10 times forging. During forging, the β phase grain experiences a series complicated process such as recovery, recrystallization and grain growth. Larger sized β phase grains can easily be formed under different conditions such as insufficient deformation or slow cooling rate during the forging process, which may affect the mechanical properties of TC18 bars. In order to find out the causes and elimination methods of large β grains, this paper used EBSD techniques to analyze the microstructure and texture of TC18 titanium bar at center layer, 1/2R layer and surface layer after the process of forging and heat treatment. Results show that a large portion of β grains experiences recovery and grain growth, while a minor portion of β grains only experiences recrystallization after α+β region heat treatment. Most β grains experience recrystallization, while for those β grains which are hard to be swallowed by recrystallized grains only experience recovery after β region heat treatment. Rather than eliminate the large sized β grains, it’s even easier for those β grains to grow up during annealing process under the condition of insufficient deformation.
Study on Continuous Annealing Process for Ultrathin Cold-Rolled SPCC Steel
Authors: Fan Wu Yan , Song Ren Bo , Zheng Ru Wen , Yao Pei Sheng
Published: April 2015

The continuous annealing process was simulated on the heat treatment system for thin steel sheet (CCT-AY-II). As the recrystallization was known, the annealing temperature and holding time were taken into account to study the influence on microstructure and mechanical properties of 0.08mm ultrathin cold-rolled SPCC steel. Combined with transmission electron microscope (TEM), the precipitation behavior was analyzed. The optical micrographs show that the microstructure of the samples are more similar to batch-annealing steel rather than general specification SPCC steel through continuous annealing. With 5°C/s heating rate and annealed at 860°C for 80s, the sample performs best: the yield strength is 161MPa, the elongation is 29% and the r-value is 1.51. AlN and MnS precipitations are observed in the inner grain and at grain boundary. The annealed textures mostly composed of {111} texture. The highest intensity is centered around the {111}<110> orientation.
Influence of the Weld Heat Input on the Electrochemical Behavior of the 921A High Strength Steel Welding Joints
Authors: Wang Kai , Yi Jiang Long , Zheng Shi Da , Guo Chun Fu , Chen He Xin , Xu Lei
Published: April 2015

Using the prepared gas-shielded flux-cored wire for welding 600MPa high strength steel, the 921A high strength steels were welded at different weld heat input condition of 10 kJ/cm, 15 kJ/cm and 20 kJ/cm. The influence of weld heat input on the electrochemical behavior of the 921A high strength steel welding joints were studied in this paper. The results show that, at different weld heat input condition, the linear polarization resistances (LPR) of all the welding joints welded by using the prepared flux-cored wire were close to that of the 921A base steel, as can be identified as the same LPR value at 15 kJ/cm weld heat input condition. By observing the surfaces of the linear polarized welding joints samples, it was found that the welding joint at 15 kJ/cm weld heat input had the smallest corrosive area by macro observing, showing the pitting corrosion by micro observing and presents the least corrosion pit.
Effect of Al-5Ti-1B Grain Refiner on Microstructure and Mechanical Properties of 7075 Aluminum Alloy
Authors: Li Tao , Wang Shun Cheng , Zheng Kai Hong
Published: April 2015

The microstructure of Al-5Ti-1B grain refiner was analyzed by XRD and SEM. The effect of the Al-5Ti-1B grain refiner on the microstructure and mechanical properties of 7075 aluminum alloy were studied. Results show that when the addition amount of Al-5Ti-1B grain refiner is 0.1%, the microstructure of 7075 aluminum alloy is refined from coarse dendrite to equiaxed grains with an average diameter of 55.1μm. The tensile strength and elongation of 7075 aluminum alloy are improved by 11.32% and 36.04% compared with that of 7075 aluminum alloy without adding Al-5Ti-1B grain refiner. With increasing the addition amount of Al-5Ti-1B grain refiner from 0.1% to 0.5%, both the tensile strength and elongation are improved. When the addition amount of Al-5Ti-1B grain refiner increases to 0.5%, the microstructure of 7075 aluminum alloy is refined to uniform equiaxed grains with an average diameter of 32.5μm. The tensile strength and elongation are improved by 18.11% and 48.76%, respectively.
Study on the Laser Precision Cutting System and Stainless Steel Microporous Cutting Technology
Authors: Han Shan Guo , Cai De Tao , Luo Zi Yi , Yan De Jun , Chen He Xin , Wang Kai
Published: April 2015

In order to improve the quality of laser cutting of stainless steel porous, the investigation on cutting 0.12mm stainless steel plates was carried out by a50W-powerbridgefiber laser cutting machine.The influence of the auxiliary line angle, laser power, and the pulse width and gas pressure on the cutting quality was studied in this paper.The results show that fewer defects was found on the samples when the cutting angle of auxiliary line was 90°and few splash orburrswas found on the samplesby 40 Wlaser power, with 56 μs pulse width and 1.3MPa gas pressure.
Hot Tensile Deformation Behaviors of an AISI 316LN Stainless Steel
Authors: Yang Xiao Ya , Wang Xi Tao , Wang Gen Qi
Published: April 2015

The hot tensile deformation behaviors of 316LN austenitic stainless steel (ASS) were studied on a Gleeble-1500D thermal simulator under the deformation temperature of 1173-1473 K and strain rate of 0.01-1 s-1. The effects of deformation temperature and strain rate on hot deformation behaviors were analyzed. Based on experimental data, the constitutive equation was established, and the predicted peak stresses by the developed model agree well with the experimental data. Microstructure near the fracture and the percentage reduction of area were studied, and the results showed that the microstructural evolution has great influences on the percentage reduction of area. Under the deformation temperature of 1473K with the strain rate of 1s-1, the grain was the finest and most homogenous, and in this deformation condition the percentage reduction of area was the highest of 79.8%.
Arrhenius-Type Constitutive Model for 316LN Stainless Steel during Hot Deformation
Authors: Xie Gan Lin , He An , Yang Xiao Ya , Zhang Hai Long , Wang Xi Tao
Published: April 2015

In this study, the hot deformation experiments of 316LN stainless steel under various deformation temperature and various strain rates were conducted on a Gleeble thermal simulator. The true stain and true stress data were obtained and the Arrhenius-type constitutive model was developed, which can be used to accurately predict the flow stress of the studied steel under certain deformation conditions.
Al-Si Alloy Foam Prepared by Two Step Foaming Method
Authors: Luo Hong Jie , Lin Hao , Zhang Jian Kun , Yao Guang Chun
Published: April 2015

Two basic methods can be used to fabricate aluminum foam. One is powder metallurgy route which can provide the near net shape casting containing aluminum foam core, and the other is melt foaming route which can prepare large scale aluminum foam plate directly. To combine the advantages of above two methods, the precursor was obtained through melt foaming route and then baked in a furnace like that of powder metallurgy method in this investigation. The test results indicated that the SiC and TiH2 particles after treatment in air could be dispersed in Al-Si matrix alloy melt and the precursors were obtained. The porosity and their pore diameter of the precursors decreased along with the temperature reducing as well as the magnesium or SiC particles adding. The density of Al-Si alloy foam decreased with the elevation of baking temperature and extension of heating time before collapse of foam block occurred. The foaming process parameters were seriously affected by the aluminum alloy composition.
Dynamic Recrystallization Behavior of a New Lead-Free Machinable Brass during Hot Deformation
Authors: Gan Chun Lei , Zheng Kai Hong , Wang Hai Yan , Qi Wen Jun , Zhou Nan
Published: April 2015

The dynamic recrystallization (DRX) behavior of the new lead-free machinable brass was investigated by compression tests on a Gleeble-1500 thermal mechanics simulator in the temperatures range of 823-973 K and strain rates ranging from 0.01 to 1 s-1. On the basis of the hot compression data, critical stress (strain) or peak stress (strain) were determined with the assistance of the strain hardening rate versus stress curves. The dynamic recrystallization kinetics model of the lead-free machinable brass was established to evaluate the DRX behavior. The results will be beneficial to optimizing hot working processes of this new lead-free machinable brass.
TiN/AlN Nano Multilayers Film Fabricated by Plasma Enhanced Atomic Layer Deposition
Authors: Jia Yi , Tang Rou Gang , Lu Wei Er , Fang You Tong , Xia Yang
Published: April 2015

TiN/AlN nanomultilayers were fabricated by plasma enhanced atomic layer deposition (PEALD). The multi-layers were characterized by HRSEM, XRD, EDS and nanoIndenter. The results showed that TiN/AlN nanomultilayers had a good periodic modulation structure, but with quite a lot of O and C contamination which were brought from PEALD process. The O and C contamination impede the crystallization of TiN, leading to a poor hardness of these nanomultilayers. No super-hardness phenomenon was identified based on Koehler theory. Much more attention needs to be paid on decreasing the O and C contamination in PEALD process.
Influence of SiC Content and Heat Treatment on the Corrosion Resis-Tance and Oxidation Resistance of Ni-P-SiC Composite Coating
Authors: Li Pan , Sun Wan Chang , Gao Jun , Zhou Quan , Zhang Pei
Published: April 2015

Ni-P alloy and SiC micron particles were codeposited on Q235 steel by electroless plating. The composition, microstructure, micro-hardness, corrosion resistance and oxidation resistance of the composite coating were studied. The results revealed that the deposited composite coating shows dispersed SiC particles and continuous Ni-P matrix. When the content of SiC was 8g/L and the heat treatment temperature was 300°C, the corrosion potential and corrosion current of Ni-P-SiC coating were-0.292V, and 8.2×10-7 A/cm2, respectively, while those of Ni-P composite coating were-0.501V, and 4.2×10-5 A/cm2, respectively. Ni-P-SiC composite coating with high content of SiC exhibits better oxidation resistance than Ni-P coating.
Influence of Strain Rate on Recrystallization Behavior of High Purity Aluminum by Tube High-Pressure Shearing
Authors: Zhou Cheng Ping , Li Zheng , Liu Fan , Wang Jing Tao
Published: April 2015

The recrystallization behavior of ultra-high purity aluminum (99.999%) during tube high-pressure shearing (t-HPS) was studied at the average strain rate of 0.2s-1 and 1.2s-1 respectively. The microstructure after t-HPS was characterized by electron backscatter diffraction (EBSD). Different recrystallization behavior at different strain rate of t-HPS was observed by the distinct microstructure evolution. The results showed that at higher strain rate, a finer grain size and higher recrystallization fraction were obtained. While the difference of recrystallization fraction between higher and lower strain rate decreased with increasing strain level. It has the potential for producing gradient materials as there is a grain size gradient along the direction of shear plane normal (SPN) which is more pronounce at strain level of ε=5.8.