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Effect of alloying elements on structure and mechanical properties of semi-solid processed cast iron
Nuchthana Poolthong 《International Journal of Cast Metals Research》2013,26(5):523-530
Semi-solid metal processing of alloys is one of the key technologies for producing advanced materials. Through semi-solid processing, it is possible to produce high quality cast components from grey cast iron. A series of experiments were carried out to clarify the effect of the alloying elements copper, chromium, molybdenum, and nickel on the properties of cast iron. A comparison was made of the microstructure and mechanical properties in semi-solid processed cast iron and ordinary cast iron. This showed that an increase in the level of alloying elements in cast iron gave a higher level of hardness. However, the tensile strength of alloyed semi-solid cast iron did not exceed that of grey iron, for every composition, as a result of the characteristic microstructure produced by semi-solid processing. Thus, the alloying elements had little effect on the tensile strength of semi-solid cast iron, but did have an effect on elongation. The tensile strength of semi-solid cast iron, however, still depends on the cooling rate. 相似文献
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The effects of trace additions of multi-alloying elements (Ti,Nb,V,Mo) on carbides precipitation and ascast microstructure of eutectic high chromium cast iron containing 2.85wt.%C and 31.0wt.%Cr were i... 相似文献
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Oscar Quilodrán 《International Journal of Cast Metals Research》2013,26(6):309-317
The graph of force versus penetration-depth from a wedge-penetration test gives information on the structure of the phases of the material under test. The simplicity of this test makes it ideal for on-line quality control of cast pieces. When strength is not satisfactory, knowledge about this structure permits a fast correction of the solidification conditions, increasing production capacity. Finally, it is proposed to adopt wedge strength as a standard, instead of converting this strength to tensile strength. 相似文献
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G. Bertolino A. A. Marengo J. E. Perez-Lpiña 《International Journal of Cast Metals Research》2013,26(5):265-274
Fracture mechanics properties in lamellar grey cast iron were traditionally evaluated from parameters calculated at maximum load values from load vs. crack mouth opening displacement records. The evaluation was carried out in this way as a consequence of the difficulty in measuring stable crack growth. The chemical tinting technique presented in this paper permits stable crack growth in lamellar grey cast iron to be measured, and then, the determination of R-Curves by a multiple specimens technique. A good agreement between the measured compliances and the theoretical ones was also observed. This demonstrates that the unloading compliance method can be used in stable crack growth measurements to determine J-R Curves. In fact, the R-Curves obtained by both methods, unloading compliance and multiple specimens, are consistent. A technological toughness value corresponding to Δa = 0.5mm, J.5 was proposed because the R-Curves set apart from the blunting line at a very early stage. Maximum load values (KPmax, Jmax and KJmax) were also determined. 相似文献
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Attila Diószegi 《中国铸造》2007,4(3):210-214
The thermal conductivity or diffusivity of pearlitic grey irons with various carbon contents is investigated by the laser flash method. The materials are cast in controlled thermal environments and produced in three dissimilar cooling rates. The cooling rate together with the carbon content largely influence the thermal conductivity of grey iron. Linear relationships exist between the thermal conductivity and the carbon content, the carbon equivalent and the fraction of former primary solidified austenite transformed into pearlite. The work shows that optimal thermal transport properties are obtained at medium cooling rates. Equations describing the thermal conductivity of pearlite,solidified as pre-eutectic austenite, and the eutectic of grey iron are derived. The thermal conductivity of pearlitic grey iron is modeled at both room temperature and elevated temperature with good accuracy. 相似文献
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The automobile engine cylinder block made of gray cast iron has complicated shape and requires high performance, which has been drawing significant attention to producers and investigators for many years. Due to the conventional conception that gray cast iron had ideal process-ability in comparison to other cast irons, the research related to the process-ability of the gray cast iron was very limited. With the strengthening corporation between China and foreign countries in the recent years, t… 相似文献
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采用等离子喷焊技术在灰口铸铁基体表面制备铁基喷焊层,喷焊两层时,喷焊层金属厚度可达8 mm。通过金相显微镜、X射线衍射仪对喷焊层显微组织进行观察分析,使用维氏显微硬度仪测试喷焊层金属显微硬度。结果表明:喷焊层显微组织主要为珠光体,基体上分布着大量的初生碳化物,初生碳化物多以(Cr,Fe)7C3形式存在。喷焊层硬度可达1 300 HV,是灰口铸铁基体的5倍以上。喷焊两层时,第一层喷焊金属组织中碳化物细化,硬度值降低,第二层喷焊金属受基体金属稀释程度的影响减小,组织更加均匀,硬度变化不大。 相似文献
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In this paper, TiC-W-Cr powders were alloyed on grey cast iron by plasma transferred arc (PTA). The alloying samples were characterized the microstructure, microhardness, fatigue life and fatigue crack growth. From the results, it is indicated that two distinguishing region: alloying zone, heat affected zone are formed on the surface after PTA alloying. The alloying zone mainly consists of primary austenite, martensite, a eutectic of (Fe,Cr)7C3 carbide and austenite as well as the uniformly distributed un-melted TiC particles. PTA alloying TiC-W-Cr eliminates the stress concentration at the edge of graphite and produced hard carbide, resulting in frequent crack deflection. As a result, the Weibull distribution of fatigue life demonstrates that PTA alloying TiC-W-Cr exhibits longer lives compared to matrix and PTA hardening without reinforcement, but more scattered. In addition, on the basis of the careful observation of fatigue crack growth, it is shown that the fatigue crack growth rate could be retarded by PTA alloying TiC-W-Cr at low stress intensity. 相似文献
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Mervat Mohamed Ibrahim Shimaa El-Hadad Mohamed Mourad 《International Journal of Cast Metals Research》2018,31(2):72-79
The effect of niobium additions on the as-cast microstructure of a hypoeutectic high-Cr cast iron containing 2.2 wt.% C and 16.5 wt.% Cr was investigated. With increasing niobium content, the eutectic M7C3 carbides were refined and became less elongated as well as its volume fraction was decreased gradually. The first precipitated NbC particles could be act as heterogeneous substrate of proeutectic austenite and a barrier to M7C3 grain growth. The morphology of NbC carbides changed with increasing niobium content. Such NbC particles were increased with increasing Nb content and subsequently contributed to increased hardness. Optimum toughness was obtained for the irons alloyed with 2.14% Nb. The effects of applied load and Nb-additions on wear resistance of high chromium cast iron have been studied. The results showed that wear resistance increases with increasing Nb addition. Furthermore, the effectiveness of the NbC particles on the weight loss was more evident at higher loads. 相似文献
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For a protective effect of oxide layers their density and their adherence to the substrate are essential. These are determined by the phase composition, the morphology and the strains in the substrate and the oxide layer. In order to determine the development of the phase composition and the strain in oxide layers in‐situ X‐ray investigations are performed. In addition to the in‐situ experiments the layer composition, morphology and texture are investigated ex‐situ after the oxidation process. The results of the experiments on a mild steel and grey cast iron reveal that the oxide layers develop fibre textures. Epitaxial strains influence the growth strains in the oxide layers. The strains and stresses present in the oxide layers after cooling to room temperature are dominated by the strain development caused by the misfit in the thermal expansion coefficient of the substrate and the different oxide sub‐layers. 相似文献
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Interaction between alloying and hardening of cast iron surface 总被引:5,自引:2,他引:5
To improve wear resistance of surface will increase the service life of gray cast iron directly.This paper presents that gray cast iron surface coated with alloy powder is locally remelted by TIG arc of increase the wear resistance.The influences of arc current and scanning rate etc on surface properties are found.Under different conditions.the microstructure,hardness and wear resistance of remelted layer are analyzed and measured.The results indicate that the gray cast iron surface can be strengthened by TIG arc local remelting treathent.Especially,surface alloying hardening effect is best and surface properties are improved remarkably. 相似文献
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A. F. Farah O. R. Crnkovic L. C. F. Canale 《Journal of Materials Engineering and Performance》2001,10(1):42-45
Wear resistance of high Cr white cast irons can be improved by means of heat treatment. This type of cast iron alloy may present
a microstructure with retained austenite. The amount of retained austenite changes with the applied heat treatment, which
will have an influence on wear properties. The purpose of this work was to study the influence of several parameters such
as quenching and tempering temperatures and subzero treatment in the wear performance of the high Cr white cast iron Nb alloy.
In this way, the performance was evaluated using pin-on-disc abrasion test. The worn surface was examined by scanning electron
microscopy, and the main wear mechanisms were identified. The microstructural characterization was also performed with carbide
identification. This Fe alloy has proven to be good for applications in mining and alcohol-sugar industries. 相似文献
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Andrzej Gruszczyk 《Welding International》2013,27(12):915-919
Results of investigations on development of new consumables for welding and weld surfacing of grey cast iron are presented. It is shown that through the influence on physical and chemical properties of liquid cast iron in the welding pool, the graphitization process, structure and properties of welds and weld overlays can be effectively affected. Arc weld surfacing with tube electrodes, without preheating or with that only up to 300°C, is a way which enables us to obtain sound weld overlays, the structure and properties of which are similar to those of grey cast iron. The method is useful for the repair of small casting defects. 相似文献
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The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease. 相似文献