Magnetic testing of the inclination to crack formation when forming rolls from йQhQxX16QMQl white iron

The correlation between the coercive force and the hardness of roll sections (butt ends, ledges, and passes) with and without cracks is investigated. It is demonstrated that inclination to crack formation can be controlled by the spread in coercimeter readings on a specific roll surface.     

The modern features of equipment for magnetic structural analysis

The new MC-10 magnetic structure analyzer is intended for the determination of different characteristics of materials and products by measuring coercive force. The MC-10 structure analyzer is compared with its older analogues: the KPM-Ц-K2M magnetic structure analyzer and KИM-2M coercimeter.     

离心铸造合金白口铸铁轧辊的研究

应用离心铸造方法,研制CrMoWVNb白口铸铁轧辊。分析合金元素在轧辊中的作用及裂纹产生原因,提出了消 除裂纹措施并应用于高速线材轧机预精轧机架,使用寿命达到高镍铬无限冷硬铸铁轧辊的4～5倍。     

合金元素对室温油分级等温淬火贝氏体球铁组织和性能的影响

采用一种新的室温油分级等温淬火工艺获得低合金贝氏体球墨铸铁;研究了硼、铜、锰对贝氏体球墨铸铁组织和性能的影响,并讨论了球墨铸铁的性能滞后现象,即等温淬火后随时问延长硬度增加的现象。结果表明：硼和锰能提高硬度,降低韧性;铜提高韧性。合理加入合金元素有利于提高贝氏体球铁的性能。贝氏体球墨铸铁有性能滞后现象,其实质是溶质类拖曳作用。     

Nondestructive Testing of Mechanical Properties of Rolled Steel (Review): 1. Tests of Strength and Plastic Properties

This review considers the creation and development of a nondestructive technique based on coercive-force measurements used to determine strength and plastic properties of industrial rolling products made from Russian-produced low-carbon and low-alloy steels. The operating principle for a coercimeter equipped with a field electromagnet is described briefly. Regression lines of mechanical properties versus coercimeter readings are presented for 20Κ- and 09Γ2-steel sheets produced by Nizhni Tagil Iron and Steel Works. Different methods for considering sheet thickness and tube dimensions are discussed.__________Translated from Defektoskopiya, Vol. 41, No. 5, 2005, pp. 39–52.Original Russian Text Copyright © 2005 by Bida.     

Magnetic tests of hardness and structure of rail steel

The correlation between the coercive force on the one side, and the structure and hardness of the rail steel on the other has been studied. A technique for testing rails quenched in oil based on measurements of the coercive force has been developed. The technique can be used in acceptance tests of rails by stages of main rail-roads.     

The role of cementite in the formation of magnetic hysteresis properties of plastically deformed high-carbon steels: II. Magnetic properties of patented wire made of steel 70

It is shown that, during discussion of the mechanism reliable for formation of the coercive force in high-carbon steel, in addition to the interaction between the domain walls and weakly magnetic cementite inclusions, the contribution from the cementite’s magnetic hardness should be considered. With the use of the temperature dependence of the coercive force in deformed and annealed specimens, the contribution of each of the considered mechanisms to the specimens’ coercive force is estimated.     

Study of arrangement efficiency of hall sensors of an attachable magnetic instrument used for recording the coercive force of a local area of an article

The use as a tested parameter of a coercimeter of the demagnetizing current that is measured at the moment of zero crossing of the magnetic flux in the magnet core by Hall sensors arranged under the electromagnet poles is shown to have an advantage over the use of the demagnetizing current measured at equal readings of Hall sensors placed in the neutral plane of the electromagnet in the leakage flux at different distances from an article.     

Modeling relations between physical properties and chemical composition of steels in quenched state

Linear statistical models with multiple parameters have been developed for predicting the magnitudes of the coercive force, saturation magnetization, electric conductivity, and hardness of highcarbon and alloyed steels of various chemical compositions quenched in the normal regimes.     

加硼高铬铸铁

从降低成本和提高耐磨性的角度出发 ,对高铬铸铁进行了加硼的试验研究。考察了加硼量和热处理工艺对高铬铸铁的硬度和冲击韧性的影响 ,并进行了销盘磨损试验。实验结果表明 :只要添加适量的硼和采取合适的热处理工艺 ,可以使高铬铸铁的碳化物细化 ,基体淬透性增加 ,并使高铬铸铁的硬度和韧性同时得到提高 ,从而增加了材料的耐磨性。     

灰铸铁表面原位合成TiC/Al3Ti复合涂层的组织及耐磨性

采用铸造反应合成技术在灰铸铁表面原位合成TiC/Al3Ti复合涂层材料,对复合涂层的显微组织、硬度和耐磨性进行了研究。结果表明:Al-Ti-C体系完全反应后可制备出纯净的TiC/Al3Ti表面复合涂层材料,该表面复合材料组织致密,并随着涂层中TiC含量的增加,材料的硬度有所提高,表面复合涂层的硬度明显高于铁基体的硬度,磨损性能也要优于铁基体,明显改善了铸铁的表面硬度和摩擦性能。       

冷硬铸铁轧辊的机加工工艺研究

冷硬铸铁轧辊辊身硬度高,耐磨性好,被广泛用于板材、线材和棒材轧机上,但同时,它也存在难以被切削加工的问题,本文探讨了冷硬铸铁轧辊的切削性能,分析了冷硬铸铁轧辊切削加工困难的原因,对冷硬铸铁轧辊切削加工工艺进行了改进,提高了切削加工的质量,并且减少了切削加工的时间。     

Influence of the sintering agglomeration regime on the magnetic properties and hardness of specimens made of powder steels 30NM and 30N2M

The dependences of the magnetic properties and hardness of powder-sintered steels 30NM and 30N2M with different densities on the sintering temperature are studied. It is shown that, for specimens with the studied compositions, there is a correlation between the combined parameter produced by the coercive force and saturation magnetization and the steel tempering temperature and hardness.     

Abrasive wear resistance of spheroidal vanadium carbide cast irons

The effect of the chemical composition and heat treatment on the microstructure and abrasive wear resistance of V-Mn, V-Ni-Cr, and V-Mo spheroidal vanadium carbide cast irons (18–23 vol %) has been studied. The wear resistance has been determined under conditions of wear by abrasives with various hardnesses, i.e., corundum and quartz and compared to that of high-chromium cast iron with 13% Cr. It has been found that the advisability of using high-vanadium cast irons is governed by the hardness of the abrasive. When a hard abrasive, i.e., corundum was used, V-Mo cast iron with the maximum concentration of spheroidal VC carbides, which were uniformly distributed in the martensitic matrix, had the highest wear resistance. When a soft abrasive, i.e., quartz, was applied, high-chromium cast iron with a hardness of 68 HRC, which contained the largest amount of M₇C₃ carbides, was more wear-resistant. In the course of isothermal exposure at 300–1000°C, V-Ni-Cr and V-Mo cast irons with an austenitic structure had high resistance to phase and structural transformations. However, the properties and microstructure of V-Mo cast irons with a martensitic matrix depended strongly on the temperature of exposure during heat treatment.     

The role of cementite in the formation of magnetic hysteresis properties of plastically deformed high-carbon steels: III. Magnetic properties of patented wire made of steel 25

Temperature dependences of the coercive force of mechanically alloyed cementite and wires made of patented steel 25 that were subjected to plastic deformation and subsequent annealing are presented. As is shown, cementite can be in both low-and high-coercivity states, for which the coercive force measured at room temperature is 80 and 240 A/cm, respectively; the coercive force measured at liquid-nitrogen temperature (?196°C) is 190 and 530 A/cm, respectively. Based on an analysis of the temperature dependences of the coercive force of deformed wires made of patented steel 25, the role of cementite in the formation of the coercive force of low-carbon steels was determined. It is shown that, in spite of a relatively small amount of pearlite, the contribution due to the magnetic hardness of cementite to the coercive force should be taken into account. In this case, the contribution due to the interaction of ferrite domain walls with weakly magnetic cementite inclusions is substantially lower.     

A study of sand slurry erosion of W-alloy white cast irons

This paper reports the results of a study into the effects of the composition, hardness and electrochemical properties of W-group cast irons on sand slurry-erosion resistance and wear mechanisms. The results indicate that the sand slurry-erosion resistance of the irons can be raised by increasing the content of tungsten, especially when the iron is alloyed with chromium. The relation between macrohardness and sand slurry-erosion is intricate. In the low hardness range, the sand slurry-erosion resistance is linearly increased with hardness, but this relationship does not exist in the high hardness range. The sand slurry-erosion resistance of cast iron can be considerably increased by increasing its corrosion resistance. Sand slurry-erosion is an abrasive wear process accompanied by corrosion and cavitation, all of which aggravate each other.     

High-Speed Machining of Malleable Cast Iron by Various Cutting Tools Coated by Physical Vapor Deposition

The coating material of a tool directly affects the efficiency and cost of machining malleable cast iron.However,the machining adaptability of various coating materials to malleable cast iron has been insufficiently researched.In this paper,turning tests were conducted on cemented carbide tools with different coatings(a thick TiN/TiAlN coating,a thin TiN/TiAlN coating,and a nanocomposite(nc)TiAlSiN coating).All coatings were applied by physical vapor deposi-tion.In a comparative study of chip morphology,cutting force,cutting temperature,specific cutting energy,tool wear,and surface roughness,this study analyzed the cutting characteristics of the tools coated with various materials,and established the relationship between the cutting parameters and machining objectives.The results showed that in malleable cast iron machining,the coating material significantly affects the cutting performance of the tool.Among the three tools,the nc-TiAlSiN-coated carbide tool achieved the minimum cutting force,the lowest cutting tempera-ture,least tool wear,longest tool life,and best surface quality.Moreover,in comparisons between cemented-carbide and compacted-graphite cast iron machined under the same conditions,the wear mechanism of the coated tools was found to depend on the cast iron being machined.Therefore,the performance requirements of a tool depend on multiple factors,and selecting an appropriately coated tool for a particular cast iron material is essential.     

The Structure and the Magnetic and Mechanical Properties of Steel M74 and the Possibility of Nondestructive Testing of Heat-Treatment-Hardened Rails

Dependences of the coercive force, the relaxation magnetization, the hardness, and the strength and plastic properties of steel M74, intended for manufacturing railroad rails, on its tempering temperature were studied. Hardened specimens have the martensite structure as well as the sorbite structure of different dispersity. Analogous dependences of critical fields, which correspond to the displacement of 180° and 90° domain walls during the magnetization reversal, and of the induced magnetic-anisotropy field were also analyzed. An MC-ИФМ magnetic structure analyzer was shown to be suitable for the nondestructive testing of the mechanical properties of finished rails. The correlation model is two-parameter; i.e., analyzer readings are used that were recorded after successive magnetization reversals of inspected sections of rails to magnetic fields corresponding to two different currents in the electromagnetic coils.     

The influence of surface oxidation on the wear resistance of cast iron

This paper reports a study of the influence of surface oxidation on the wear resistance of ductile iron, grey iron and vermicular iron during dry sliding friction. The mechanisms of wear are also reported. This study shows that the effect of surface oxidation (formed under normal atmospheric conditions) on the wear rate depends on the complex functions of graphite morphology and matrix structure. Generally the presence of surface oxidation decreases the wear rate of grey iron but increases the wear rate of ductile iron and vermicular iron when the cast iron has high hardness. This trend is reversed for low hardness cast iron.     

An attachable electromagnet of a coercimeter with an indicating system between the electromagnet’s poles

The dependence of the readings of a coercimeter on the gap width between an article and the poles of an attachable electromagnet (AEM) at different magnetizing and magnetization-reversing currents is studied in the case when the indicator of the magnetic state of an article is removed from the electromagnet’s magnetic circuit and placed between the electromagnet’s poles on the surface of the article. It is shown that, during coercive-force measurements, such an indicator cannot be used for determining the demagnetized state of the article in the case of substantial fluctuations of the gap between the AEM poles and the article, although it can be used for assessing the gap width.