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石墨形态和铬含量对铸铁干摩擦学性能的影响 总被引:3,自引:0,他引:3
使用MM—200磨损试验机研究了石墨形态和铬含量对铸铁与石棉基摩擦材料配副时的干摩擦学性能。结果表明,蠕墨铸铁的磨损率最低;摩擦系数由高到低依次为:片墨铸铁、蠕墨铸铁、球墨铸铁。蠕墨铸铁中,随着铬含量的增加,耐磨性能明显提高,摩擦系数略有降低。在高速、高载荷条件下,铬含量的质量分数达到1.5%时,耐磨性可达普通蠕墨铸铁的4倍以上;随着载荷的增加,蠕墨铸铁的摩擦系数降低,磨损率提高。在高速条件下,摩擦系数降低的幅度比在低速条件下小。铬改善蠕墨铸铁干摩擦学性能的效果在高速使用条件下更为突出。 相似文献
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Pig iron ingot molds manufactured with flake, compacted graphite cast iron, and spheroidal graphite cast iron were installed
on a pig iron casting machine and subjected to thermal cycling for studying thermal fracture endurance of the three cast irons.
The effects of graphite morphology on the fracture mechanism were analyzed by examining the fracture patterns, microstructures,
and microcracks in the failed molds. The determining factors of thermal fracture endurance were elucidated with thermal fracture
resistance indices. Compacted graphite cast iron exhibited better thermal fracture endurance than flake and spheroidal graphite
cast irons because of its higher strength-to-thermal stress ratio. 相似文献
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Effect of RE Modification and Heat Treatment on Impact Fatigue Property of a Wear Resistant White Cast Iron 总被引:5,自引:0,他引:5
Withhigherhardnessandbetterwearresistance ,whitecastironscanbeusedaswearresistantpartsinmanyfields .Inpractice ,thewearresistantpartsareoftenrequiredtobesubjectedtogrindingofabrasivesandrepeatedimpactaction .Therefore ,fatiguecracksareliabletobegeneratedo… 相似文献
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选用3种具有不同Ce含量的球化剂FeSiMg6RE2、FeSiMg8RE3和FeSiMg8RE5对铁液进行盖包法处理,球化处理后浇注成180mm×180mm×200mm的球铁试块。通过室温拉伸、光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析仪(EDS)和低温冲击试验机等分析手段,研究了稀土元素Ce对大断面低温球铁的石墨组织、力学性能和低温冲击韧性的影响。结果表明:用稀土含量低的球化剂FeSiMg6RE2进行处理,试样的石墨组织细小均匀,石墨形态好,低温冲击韧性高,冲击功平均值约为14.5J;用稀土含量高的球化剂FeSiMg8RE3和FeSiMg8RE5分别进行处理,试样中出现了大面积碎块状石墨等变异组织,低温冲击韧性差,冲击功平均值分别约为6.5和5.1J。能谱分析结果表明:高稀土含量球化剂处理的球铁试样,石墨组织晶界上发生了稀土元素Ce的富集,其质量分数分别约为0.36%和0.42%,这是造成铸件中碎块状石墨等变异组织产生的根本原因,严重恶化了铸件的力学性能。 相似文献
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K. Takai Y. Chiba K. Noguchi A. Nozue 《Metallurgical and Materials Transactions A》2002,33(8):2659-2665
The distribution and desorption processes of hydrogen and deuterium have been visualized by secondary ion mass spectrometry
(SIMS). The present article deals with four principal points: (1) visualizing the hydrogen distribution, (2) visualizing the
hydrogen desorption process from each metallurgical microstructure under various holding times at 25 °C, (3) visualizing the
hydrogen desorption process during heating, and (4) determining the correspondence between desorption profiles and desorption
sites. A spheroidal graphite cast iron specimen was prepared for visualizing hydrogen, since it consists of basic microstructures
of steels such as ferrite and pearlite. Hydrogen and deuterium were occluded into the cast iron. The amount of hydrogen and
the existing states of hydrogen in the cast iron were analyzed by thermal desorption spectrometry (TDS). The TDS analyses
show that the hydrogen desorption has two peaks, namely, the low- and high-temperature peaks corresponding to trap activation
energies of 21.6 and 105.8 kJ/mol, respectively. The SIMS analyses of the specimen cooled after heating to 100 °C, 200 °C,
and 300 °C reveal that the hydrogen desorbs from the ferrite after heating to 100 °C, from the pearlite and the interfaces
between the ferrite and the graphite after heating to 200 °C, and from the pearlite after heating to 300 °C. The graphite
remains, trapping hydrogen after heating to 300 °C. On the basis of TDS and SIMS results, the relationship between the desorption
profile and desorption sites was identified; that is, the low-temperature peak corresponds to ferrite, pearlite, and graphite/ferrite
interfaces, while the high-temperature peak corresponds to graphite. 相似文献
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Masoud Zandira 《钢铁研究学报(英文版)》2010,17(2):31-35
The fracture characteristics of austempered spheroidal graphite aluminum cast iron had been investigated. The chemical content of the alloy was C 3.2, Al 2.2, Ni 0.8 and Mg 0.05 (in mass percent, %). Impact test samples were produced from keel blocks cast in CO2 molding process. The oversized impact samples were austenitized at 850 and 950 ℃ for 2 h followed by austempering at 300 and 400 ℃ for 30, 60, 120 and 180 min. The austempered samples were machined and tested at room temperature. The impact strength values for those samples austempered at 400 ℃ varied between 90 and 110 J. Lower bainitic structures showed impact strength values of 22 to 50 J. The fractures of the samples were examined using SEM. The results showed that the upper bainitic fracture revealed a honey Comb-like topography, which confirmed the ductile fracture behavior. The lower bainitic fractures of those samples austempered for short times revealed brittle fracture. 相似文献
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研究了含钒蠕墨铸铁与钢盘对磨时的干摩擦学性能。结果表明,钒的加入降低了蠕墨铣的的磨损量,提高了接触压力和摩擦速度变化时磨损量的稳定性。含钒0.1%和0.3%时,提高了摩擦系数和高接触压力,高摩擦速度下降摩擦系数稳定性。 相似文献
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Effect of Rare Earth Elements on Carbide Morphology and Phase Transformation Dynamics of High Ni-Cr Alloy Cast Iron 总被引:6,自引:0,他引:6
EfectofRareEarthElementsonCarbideMorphologyandPhaseTransformationDynamicsofHighNiCrAloyCastIronYangQingxiang(杨庆祥),LiaoBo(廖波... 相似文献
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This study investigates the thermal fatigue cracking behavior of high-silicon spheroidal graphite (SG) cast iron. Irons with
different residual magnesium contents ranging from 0.038 to 0.066 wt pct are obtained by controlling the amount of spheroidizer.
The repeated heating/cooling test is performed under cyclic heating in various temperatures ranging from 650 °C to 800 °C.
Experimental results indicate that the thermal fatigue cracking resistance of high-silicon SG cast iron decreases with increasing
residual magnesium content. The shortest period for crack initiation and the largest crack propagation rate of the specimens
containing 0.054 and 0.060 wt pct residual magnesium contents are associated with heating temperatures of 700 °C and 750 °C.
Heating temperatures outside this range can enhance the resistance to thermal fatigue crack initiation and propagation. When
thermal fatigue cracking occurs, the cracks always initiate at the surface of the specimen. The major path of crack propagation
is generally along the eutectic cell-wall region among the ferrite grain boundaries, which is the location of MgO inclusions
agglomerating together. On the other hand, dynamic recrystallization of ferrite grains occurs when the thermal cycle exceeds
a certain number after testing at 800 °C. Besides, dynamic recrystallization of the ferrite matrix suppresses the initiation
and propagation of thermal fatigue cracking. 相似文献
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Thermal wear of cast hot-forging die steel modified by rare earths(RE) was studied and compared with commercially used die steels. The function of RE and the mechanism of thermal wear of cast steel modified by RE were discussed. The results showed that with increasing content of RE, the wear rate of cast steel reduced at first and then increased. By adding 0.05% (mass fraction) RE, the cast hot-forging die steel with optimum thermal wear resistance was obtained, which was better than that of H13 and 3Cr2WSV. The large amount of coarse inclusions, (RE)2O2S, resulted from excessive RE, which obviously deteriorated thermal wear resistance. The mechanism of thermal wear of the modified cast die steel is oxidation wear and oxide fatigue delamination. The wear debris are lumps of Fe2O3 and Fe3O4. 相似文献
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Raghavendra Hebbar 《Transactions of the Indian Institute of Metals》2011,64(3):265-269
An attempt has been made to assess the grinding wear behaviour of austempered ductile iron (ADI) as media material in comminution of Kudremukh haematite iron ore in a ball mill. Spheroidal graphite (S.G) iron balls were austenitised at 900°C for one hour and austempered at 280°C and 380°C for different time durations. These materials were characterized by measuring hardness, carrying out X-ray diffraction analysis, studying microstructures using scanning electron microscope (SEM). Grinding wear behaviour of ADI was assessed during wet grinding at different pH of the mineral slurry. The wear resistance of ADI was compared with that of forged En 31 steel balls under similar grinding conditions. It was found that ADI balls austempered at 280°C for 30 minutes which contains lower bainite registered superior wear resistance. It was also noted that the wear resistance of ADI was more at higher pH range of the slurry. 相似文献