Effect of heat treatment on microstructure and mechanical properties of Ti-containing low alloy martensitic wear-resistant steel

Effects of quenching temperature and cooling conditions(water cooling and 10%NaCl cooling)on microstructure and mechanical properties of a 0.2%Ti low alloy martensitic wear-resistant steel used for die casting ejector plate were investigated.The results show that lath martensite can be obtained after austenitizing in the range of 860-980℃and then water cooling.With an increase in austenitizing temperature,the precipitate content gradually decreases.The precipitates are mainly composed of TiC and Ti4C2S2,and their total content is between 1.15wt.%and 1.64wt.%.The precipitate phase concentration by water-cooling is higher than that by10%NaCl cooling due to the lower cooling rate of water cooling.As the austeniting temperature increases,the hardness and tensile strength of both water cooled and 10%NaCl cooled steels firstly increase and then decrease.The experimental steel exhibits the best comprehensive mechanical properties after being austenitized at 900℃,cooled by 10%NaCl,and then tempered at 200℃.Its hardness,ultimate tensile strength,and wear rate reach551.4 HBW,1,438.2 MPa,and 0.48×10^(-2)mg·m^(-1),respectively.

Microstructures and wear-resistant properties of in-situ TiC_p/ZA-12 composites

TiC_p/ZA-12 composites were fabricated by exothermic disposition method process and stirring-casting techniques. The microstructure and wear-resistant properties were investigated . The results show that TiC particles are formed in-situ and distributed uniformly in matrix. No particles aggregation and macro or micro precipitation are observed. The wear-resistant properties of composites increase with the increase of TiC_p content, but will not increase when the TiC_p content reaches constant value. Finally, the friction and wear mechanism were also discussed.

Effects of air-atomized water spray cooling device structure on the quenching process,microstructure,and properties of wear-resistant steel

With its high strength and hardness, wear-resistant steel has become an important material in the field of construction machinery manufacturing.Given that quenching technology is a crucial component of wear-resistant steel production, the selection of the cooling method to be used during this process is important.In this study, the feasibility of quenching wear-resistant steel by air-atomized water spray cooling was studied, and the cooling rate, microstructure, and hardness of wear-resistant steel under various cooling device structures were analyzed.The results reveal that the air-atomized water spray cooling method is an effective technique in quenching wear-resistant steel.Furthermore, martensite and uniform hardness were obtained by the air-atomized water spray cooling technique.As the space between the nozzles in each row in the device increased, the cooling rate was reduced during quenching.Meanwhile, the martensite content decreased, and more carbides were observed in the martensitic structure.A mixture comprising self-tempered martensite and bainite was formed at a large distance over a longer period of time.All these factors resulted in lower hardness and worse property uniformity.

Numerical simulation of temperature field in laser-arc hybrid welding of wear-resistant steel

Using ABAQUS software and cylindrical ellipsoid and body heat sources with a peak-heat-flux- attenuation function, a finite element model of the temperature field in the laser-arc hybrid welding of 4.5-mm BW300TP wear-resistant steel is proposed. The proposed model considers convection, radiation, molten pool flow, and heat conduction effect on temperature. A comparison of the simulation and actual welding test results confirms the reliability of the model. This welding heat-process model can provide the cooling rate at any position in the heat affected zone （HAZ） and can be used as a reference for the analysis of material properties and for process optimization.

Hot cracking susceptibility research in BTW1 austenitic high-manganese wear-resistant steel

Baosteel’s first BTW1 austenitic high-manganese wear-resistant steel exhibits strong deformation-induced hardening characteristics.Compared with common low-alloy martensitic wear-resistant steels in the market, it has improved impact wear resistance, hard abrasive wear, erosion wear performance, and impact toughness.The metallurgical properties of such austenitic wear-resistant steel lead to the risk of failure because of hot cracking defects in the welded structure.In wear-resistant applications, evaluating hot cracking susceptibility is necessary to avoid the effect of welding defects.In this study, the Varestraint test is used to quantitatively analyze and evaluate the hot cracking susceptibility of BTW1 austenitic high-manganese wear-resistant steel.The test results show that by controlling the content of impurity elements and grain refinement, BTW1 austenitic high-manganese wear-resistant steel effectively reduces hot cracking tendency and has a low incidence of hot cracking under small strain conditions.The developed matching welding process can effectively avoid the influence of hot cracking susceptibility.

Developing Maanshan Kuangyou Wear-resistant Materials Group Company

Maanshan KuangyouGroup company is a special largeenterprise making wear-resistantmaterials products,integratingscience,industry and trade.Mainproducts are chromium-contentwear-resistant materials and ship-use anchor chains."Kuangyou"Brand balls have been awardedprizes of Quality Products by theprovince and ministry,and prizeof Scientific Progress by theprovince,and are widely appliedin mining,cement,power andchemicals industries.Ship-useanchor chains have an

Synthesis and Coloring Mechanism of Metallic Glaze in R_(2)O-RO-Al_(2)O_(3)-SiO_(2)-P_(2)O_(5)System

A copper-red and silver-white metallic glaze of R_(2)O-RO-Al_(2)O_(3)-SiO_(2)-P_(2)O_(5)system was synthesized by adjusting the firing temperature and glaze components.The coloration mechanism of the metallic glaze was revealed via investigation of the microstructure of the glaze.Our research reveals that the metallic glaze with different colors is mainly due to the amount of Fe_(2)O_(3).The metallic glaze shows a silver-white luster due to a structural color ofα-Fe_(2)O_(3)crystals with a good orientation when the sample contains 0.0939 mol of Fe_(2)O_(3),maintaining temperatures at 1150℃for 0.5 h.The metallic glaze is copper-red which is dominated by the coupling of chemical and structural color ofα-Fe_(2)O_(3)crystals when the sample contains 0.0783 mol of Fe_(2)O_(3).After testing the amount of SiO_(2),we find that 4.0499 mol is the optimal amount to form the ceramic network,and 0.27 mol AlPO_(4)is the best amount to promote phase separation.

北宋定窑茶叶末釉的微观结构与矿物形态学研究

茶叶末釉古瓷作为最早出现的结晶釉之一,开展深入研究可明确其矿物晶体特征、呈色机理以及古代烧制工艺,丰富古陶瓷数据库。目前相关研究多来源于二十世纪末,样本稀少且囊括的年代和窑口严重不足,所用科学仪器多已淘汰,亟需更多实验分析与数据支撑。本文采用光学显微镜(OM)、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)、扫描电镜-能谱(SEM-EDS)、激光共聚焦拉曼光谱(LRS)、飞行时间二次离子质谱(ToF-SIMS)等现代科学仪器对北宋定窑茶叶末釉样本中矿物晶体开展了分析和表征。结果表明,釉中主晶相与辽金龙泉务窑一致,为钙长石和辉石;釉面整体表现为酱-黑色釉基质富铁(Fe2O3含量均值9.73%)和矿物结晶富铁(Fe2O3含量均值11.33%),除α-Fe2O3和Fe3O4晶体等熔后重结晶矿物,还有铁镁尖晶石、残余高岭石等未融熔矿物,反演出制釉原料中有镁的加入以及烧成温度可能低于1200℃,异于前人高温烧制的观点。SIMS离子成像揭示了胎釉交界处为厚约20~80μm的钙长石晶体层,而非化妆土或玻璃态的致密反应层。研究揭示了茶叶末古瓷中Fe元素不均匀富集,部分区域过饱和而析出含铁矿物晶体,釉面颜色则主要由黄褐色的矿物晶体斑点和酱-黑色玻璃基质共同组成,同时ToF-SIMS在古瓷微区原位的形貌结构和元素分析上效果显著,能够辨别钙长石、碱性长石等微米级矿物。

Wear-resisting Oxide Films for 900℃

A study was conducted to develop low-friction, wear-resistant surfaces on high temperature alloys for the temperature range from 26℃ to 900℃. The approach investigated consists of modifying the naturally occurring oxide film in order to improve its tribological properties. Improvement is needed at low temperatures where the oxide film, previously formed at high temperature, spalls due to stresses induced by sliding. Experiments with Ti, W and Ta additions show a beneficial effect when added to Ni and Ni-base alloys. Low friction can be maintained down to 100℃ from 900℃. For unalloyed Ni friction and surface damage increases at 400℃ to 500℃. Two new alloys were perpared based on the beneficial results of binary alloys and ZrO2 diffusion in Ni.Low friction at temperature above 500℃ and reasonable values (0.32~0.42) at low temperature are obtained.

The effect of single-horn glaze ice on the vortex structures in the wake of a horizontal axis wind turbine

The present study experimentally investigated the effect of a simulated single-horn glaze ice accreted on ro- tor blades on the vortex structures in the wake of a hori- zontal axis wind turbine by using the stereoscopic particle image velocimetry （Stereo-PIV） technique. During the ex- periments, four horizontal axis wind turbine models were tested, and both ＂free-run＂ and ＂phase-locked＂ Stereo-PIV measurements were carried out. Based on the ＂free-run＂ measurements, it was found that because of the simulated single-horn glaze ice, the shape, vorticity, and trajectory of tip vortices were changed significantly, and less kinetic en- ergy of the airflow could be harvested by the wind turbine. In addition, the ＂phase-locked＂ results indicated that the pres- ence of simulated single-horn glaze ice resulted in a dramatic reduction of the vorticity peak of the tip vortices. Moreover, as the length of the glaze ice increased, both root and tip vortex gaps were found to increase accordingly.

MICROSTRUCTURES OF A NOVEL HIGH STRENGTH AND WEAR-RESISTING ZINC ALLOY

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Investigation on surface figuration and microstructure of laser glazed nanostructure zirconia thermal barrier coatings

CO2 continuous wave laser beam had been applied to the laser glazing of plasma sprayed nanostructure zirconia thermal barrier coatings. The effects of laser glazing processing parameters on the surface figuration and microstructure change had been carried out, the microstructure and phase composition of the coatings had been evaluated by the scanning electron microscope （ SEM） and the X-ray diffraction （ XRD ）. SEM observation indicates that the microstructure of the as-glazed coating could be altered from singlecolumnar structure to a combination of the columnar grain and fine equiaxed grain with the different laser glazing conditions. XRD analysis illustrates that the predominance phase of the us-glazed coating is the metastable tetragonal phase, and the glazed coating with the single columnar structure has shown the clear orientation in （220） and （400） peaks while the other coatings do not show that.

Effect of Fly Ash on Drying Shrinkage of Thermal Insulation Mortar with Glazed Hollow Beads

Drying shrinkage of thermal insulation mortar with glazed hollow beads was measured by a vertical length comparator, and the influences of fly ash with different contents（0, 18%, 36%, and 54% were used） on the long-term drying shrinkage were discussed. The mass loss was measured by the weighting method and the pore structure was characterized using three different methods, including the light microscopy, the mercury intrusion porosimetry（MIP）, and the nitrogen adsorption/desorption（NAD） experiments, and the correlations among them were researched. The results show that drying shrinkage process of thermal insulation mortar includes three steps with increasing curing time： the acceleration period（before 7 d）, the deceleration period（7-365 d）, and the metastable period（after 365 d）. Drying shrinkage in the first stage（7 d before） increases quickly owing to the fast water loss, and its development in the last two stages is attributed to the increment of the pore volume of mortar with the radius below 50 nm, especially the increment of the pore volume fraction of the pore radius within the size range between 7.3 nm and 12.3 nm. There is no change in the drying shrinkage development trend of mortar with fly ash addition, and three steps in the service life, but fly ash addition in the mortar restrains its value. There is a linear relationship between the drying shrinkage and fly ash content, which means that drying shrinkage reduces with fly ash addition.

A Novel Infrared Radiant Glaze Exhibiting Antibacterial and Antifungal Functions

Infrared radiant powder was synthesized by conventional ceramic processing techniques by using Fe2 O3, MnO2, CuO, Co2 O3 and kaolin as raw materials. A novel infrared radant glaze was developed by introducing the infrared radiant powder into glazing as a functional additive. Infrared radiant characteristics of the powder and the glaze were investigated. The optimum content of infrared radiant powder in glazing was ascertained to be 5% . The infrared radiant glaze exhibits significant antibacterial and antifungal Junctions due to the thermal effect of infrared radiation. Antibacterial percentages of the glaze reach 91% - 100% when Escherichia coli, Staphylococcus aureus and Bacillus subtilis are used as model bacterium respectively, while antifungal percentage of the glaze exceeds 95% when Penicillum citrinum is used as model fungus.

Elements inter-diffusion in the turning of wear-resistance aluminum bronze

Inter-diffusion of elements between the tool and the workpiece during theturning of aluminum bronze using high-speed steel and cemented carbide tools have been studied. Thetool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turna novel high strength, wear-resistance aluminum bronze without coolant and lubricant. Adhesion ofworkpiece materials was found on all tools' surface. The diffusion couples made of tool materialsand aluminum bronze were prepared to simulate the inter-diffusion during the machining. The resultsobtained from tool wear samples were compared with those obtained from diffusion couples. Stronginter-diffusion between the tool materials and the aluminum bronze was observed in all samples. Itis concluded mat diffusion plays a significant role in the tool wear mechanism.

Effect of Rare Earths-Treated Glass Fiber on Impact Wear-Resistance of Metal-Plastic Multilayer Composites

The friction and wear properties under impact load and dry friction conditions of metal-plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear-resistance.

Preparation of Lead-free Base Glaze Suitable for Pearlescent Pigments by Low-temperature Solid-phase Reaction with Alkali Waste

A lead-free base glaze suitable for pearlescent pigments was prepared by a low-temperature solid-phase reaction with alkali waste.Tests were performed to evaluate the effects of the sintering conditions and alkali waste composition on the prepared base glaze and pearlescent glaze.The experimental results show that partially replacing SiO_(2) with B_(2)O_(3) effectively reduced the sintering temperature and time to form a glass network,but the network structure becomes disconnected as the B_(2)O_(3) content increases.An amorphous base glaze was obtained when soda ash was replaced with a small amount of alkali waste,but increasing the addition of NaCl further was adverse to base glaze formation by resulting in crystallization of the base glaze and a decrease in the bridging oxygen content.The pearlescent pigment was thermally stable in the glaze at 750℃,while higher temperatures caused the crystalline phase of NaAlSiO_(4) to appear and adhere to the surface of pigment granules,which degraded the pearlescent effect of the glaze.

Wear-resistance Performance of Spray-welding Coating by Plasma Weld-surfacing

Alloy powders including Ni60, WC, CrC, and TiC with different mass ratios were deposited on medium carbon low alloy steel by plasma welding. Through the experiments, the optimal alloy powder reinforcing cutter tool surface properties were discovered. The wear resistance properties were investigated on the impact abrasive wear tester. The experimental results show that in terms of microstructure, there exists the shape of herringbone, spider mesh, broken flower structures in coatings. In addition, fusion area of four specimens surfacing welding layer displays a large number of acicular martensite with a small amount of austenite. The coating mainly consists of Ni-Cr-Fe austenitic phase and the other precipitates. TiC density is smaller, its content is less in alloy powder, in the process of surfacing welding, TiC is melted fully, which is mainly distributed in surface layer and middle layer of hard facing layer. The content of TiC gradually reduces from surface layer of hard facing layer to the fusion area. Compared to TiC, the density of tungsten carbide and chromium carbide is larger, there exist tungsten carbide and chromium carbide particles, which are not completely melted near the fusion area. The micro-hardness presents gradient change from the fusion area to the surface layer of hard facing layer, and the hardness of the middle layer is slightly lower than that of the fusion area, and the hardness increases near the surface layer.

Application of cetylpyridinium chloride in dispersion of antibacterial ceramic glaze

The adsorption of cetylpyridinium chloride(CPC)onto a ceramic glaze mixture composed of limestone,feldspar,quartz,kaolin,and antibacterial agent was studied.Both adsorption isothermals and the average particle zeta potential were investigated in order to understand the suspension stability as a function of pH,ionic strength,and surfactant concentration.The results show that under the optimal conditions such as pH value of 7 or 9,0.01 mol/L of ionic strength and around critical micelle concentration(CMC)of surfactant,antibacterial ceramic glaze acquires fine dispersion stability.The adsorption of CPC on ceramic glaze particles is in accordance with Langmuir model in 0.01mol/L at pH=7 and pH=9.The adsorption of small amounts of cationic CPC onto the primarily negatively charged surfaces of the particles in the pH range of 7?9 produces strong attraction and flocculation due to hydrophobic interactions.High concentration of surfactant under 0.01 mol/L of salt provides high zeta potential,which produces a high stability.

A New Ceramic Substrate Glaze with High Resistance to Molten Aluminum

Corrosion resistance of ceramic substrate glazes to molten aluminum was studied in this paper. The glazes can spread slightly in aluminum alloy according to SEM examination of solidified interface between the glazes and aluminum alloy. The components of B2O3-P2O5 glazes were not detected with electron probe at the side of aluminum alloy near the interface, but the components of boron-free glaze were detected. It is shown that borophosphate glazes can resist the corrosion of molten aluminum.