Influence of structural features of welded joints of low-alloy steels on magnetic and micromagnetic properties

Variations of magnetic (coercive force H _c , residual induction B _r , maximum magnetic permeability μ_max, maximum magnetic-permeability field H _μmax, saturation magnetization J _max) and micromagnetic (number of pulses N and RMS Barkhausen-noise amplitude U) characteristics along the parent metal-welded joint direction were studied for welds of steels 10XCHД, 15XCHД, 09Γ2C, and X70.     

Comparison of wear properties of tool steels AISI D2 and O1 with the same hardness

Two commercial cold work tool steels, AISI D2 and O1, were heat treated in order to obtain the same hardness 700 HV (60 HRc) and were subsequently tested in three different modes of wear, namely in adhesion, three-body and two-body abrasion, by using pin-on-disk, dry sand/rubber wheel apparatus and pin abrasion on SiC, respectively. Even though AISI O1 and D2 steel are heat treated to the same hardness, they perform differently under the three modes of wear examined. The results show that the steel microstructures play the most important role in determining the wear properties. For relatively low sliding speeds AISI O1 steel performs up to 12 times better than AISI D2 steel in adhesive wear. For higher sliding speeds, however, this order is reversed due to oxidation taking place on the surface of the AISI D2 steel. The wear rate of both tool steels in three-body and two-body abrasion wear is proportional to the applied load. In three-body abrasive wear, AISI D2 exhibits a normalised wear rate about two times lower than the AISI O1 tool steel, and this is due to the presence of the plate-like hard carbides in its microstructure. Both tool steels perform 3–8 times better in three-body abrasive wear conditions than in two-body abrasive wear.     

Mixed-surface impregnation of gear wheels made of 13Kh3N3M2VFB-Sh age-hardenable integrally alloyed steel aimed at improving surface hardness,wear-resistance,and back-to-back endurance

An analysis has been carried out of mixed-surface impregnation of the 13Kh3N3M2VFB-Sh age-hardenable integrally alloyed steel consisting of successive vacuum carburizing, heat treatment, grinding and nitriding in the glow-discharge was made. Test results of samples hardened by mixed-surface impregnation for back-to-back endurance and wear resistance have been presented. It has been shown that mixed-surface impregnation combines the advantages of vacuum carburizing and nitriding. A surface hardness of more than 1000 HV has been achieved via the mixed-surface impregnation of this stated steel.     

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.     

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.     

Choice of the parameters and algorithm for the magnetic hardness testing of thermally treated carbon steels by the method of regression modeling

The possibility of testing the hardness of quenched and tempered medium-carbon steels using their magnetic properties is studied. It is shown that the two-parameter method should be applied for the reliable estimation of the hardness. The coercive return magnetization (induction) and the coercive force must be used as the basic and subsidiary parameters of testing, respectively. It is established that the content of carbon in steel influences the sensitivity of testing. It is shown that the suggested magnetic hardness testing method can be practically implemented with the use of the modernized SIMTEST-2.10 system.     

Effect of the hardness of hardened steels and the action of oxides on fretting wear

The influence of hardness on fretting wear was investigated experimentally in air using a bearing-steel ball sliding on a 0.6% C steel plate under a load of 34.3 N at a frequency of 16.6 Hz. The total number of cycles was 10⁵ and peak-to-peak amplitudes of 45 and 260 μm were used. The hardness of both materials was varied from 220 to 850 HV.Hardness had only a minor influence on fretting wear. The significant factor was the action of any black oxide produced. The black oxide reduced the wear of the surface from which it was generated but acted as an abrasive against the opposing surface. At a sliding amplitude of 260 μm there were discontinuities on the wear curves due to the formation of black oxide. Similar wear characteristics were obtained with an amplitude of 45 μm except that some heavy damage due to adhesion and material transfer occurred.     

The effect of cementite on the formation of the magnetic hysteresis properties of thermally treated carbon steels

The role of cementite in the mechanisms of formation of the coercive force of high-purity 60 and 13 model steels and 9A and 12A industrial steels after quenching and subsequent medium- and high-temperature tempering is determined from the analysis of the temperature dependences of the coercive force. It is shown that cementite as a hard-magnetic phase plays an important part in the formation of the dependence H _c (T _temp) measured at room temperature. The maximum contribution caused by the coercivity of cementite to H _c of the model steels is proportional to the volume content of cementite. In the industrial steels, an effect on the coercivity of cementite is produced by carbideforming unavoidable impurities.     

N2流量对多弧离子镀ZrTiN涂层性能的影响

采用离子束轰击辅助多弧离子镀法,在硬质合金YT15刀片上沉积ZrTiN涂层.研究了沉积过程中不同N2流量对ZrTiN涂层性能的影响,结果表明:当N2流量为140 mL/min时,涂层表面熔滴、缺陷较少,表面平整,粗糙度值最小.在该N2流量下,由于真空室内各种粒子结合率较高,沉积速率适中,涂层生长致密,其硬度和结合力的综合性能最佳,另外当N2流量为120 mL/min时,涂层沉积速率最快达到24.6 nm/min.     

Local determination of the field of induced magnetic anisotropy and the level of residual mechanical stresses in tensile-deformed bodies made of low-carbon steels

A novel primary attachable transducer has been developed. The transducer makes it possible to estimate the level of residual mechanical stresses at local spots of articles that are made of lowcarbon steels. The critical fields of displacement of 90-degree domain boundaries have been determined experimentally by using a technique that allows one to separate contributions from two types of domain boundaries to the magnetization reversal by means of simultaneous action of two orthogonal magnetic fields. Optimum operating parameters of the primary transducer have been established.     

Influence of CNTs addition on the mechanical,microstructural, and corrosion properties of Al alloy using spark plasma sintering technique

The International Journal of Advanced Manufacturing Technology - Monolithic aluminium 1000 alloy is used in overhead transmission conductors because of its light weight, high electrical...     

The role of cementite in the formation of magnetic hysteresis properties of plastically deformed high-carbon steels: I. Magnetic properties and structural state of cementite

Magnetic properties of cementite after strong plastic deformations and subsequent annealing in a broad range of temperatures are studied. The plastically deformed cementite is shown to exist in a soft (H _c ≈ 80 A/cm) state; the annealed cementite, in a hard (H _c ≈ 240 A/cm) state. The nature of the cementite’s soft and hard states is discussed. The field dependence of the cementite’s magnetostriction is measured. The longitudinal magnetostriction of the polycrystalline cementite’s saturated state is shown to be negative and approximately four times smaller than iron’s magnetostriction in the saturated state.     

Influence of friction on the local mechanical and electrochemical behaviour of duplex stainless steels

The electrochemical behaviour of ferritic and austenitic phases in duplex stainless steel (UNS S32304) and the modifications induced by straining during sliding were studied by potentiodynamic polarisation curves determined at the microscale in a 1 M NaCl (pH 3) solution, using an electrochemical microcell. The mechanical properties and stress state of each phase were determined by microhardness and X-ray microdiffraction measurements, before and after straining. The results show that sliding generates elastic straining of the ferrite and plastic deformation of the austenite. The electrochemical behaviour of these phases is dramatically altered, inducing a reduction of the corrosion resistance and of the passivation properties.     

Experimental investigations on the microstructure and mechanical properties of sinter-forged Cu and Mo-alloyed low alloy steels

The present investigation pertains to the study of the mechanical properties and fracture behavior of sinter-forged low alloy steels containing copper (Cu) and molybdenum (Mo) as alloying elements. Elemental powders of atomized iron, graphite, molybdenum, and copper were mixed in suitable proportions using a ball mill, compacted in a 1,000 kN hydraulic press using suitable cylindrical die–punch combination and sintered at 1,000 ± 10°C in a muffle furnace for a period of 120 min in order to yield the alloy compositions (by weight) such as Fe–0.5% C, Fe–0.5% C–1% Cu, Fe–0.5% C–2% Cu, Fe–0.5% C–1% Mo, and Fe–0.5% C–2% Mo. The sintered cylindrical preforms were then subjected to hot upset forging to near theoretical density and subsequently machined off to standard size in order to carry out the mechanical tests such as hardness, tensile, and impact tests. Addition of Cu and Mo to the plain carbon steel has been observed to enhance the tensile strength as well as hardness of the sinter-forged alloys. The presence of Mo carbides in the microstructure of the alloys further reinforces this observation. The impact strength of this alloy has been observed to be reduced considerably due to the addition of the alloying elements.     

Effect of ozone pretreatment on the physical and mechanical properties of particleboard panels made from bagasse

The main objective of this study was to investigate the applied properties of particleboard panels made from bagasse, which were either treated or not treated with gaseous ozone (O₃). Variable parameters were ozone exposure time (1–3 min) at 9 ppm and storage period (1–5 months). Other parameters such as resin content (12 wt%), hardener content (1 wt%), type of hardener (NH₄Cl), press closing time (5 mm/s), board density (0.70 g/cm³), and press pressure (30 kg/m²) were held constant. The experimental panels were tested for their mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR); and internal bonding strength (IBS) and physical properties in terms of water absorption (WA) and thickness swelling (TS) according to the procedures defined by EN standards. Overall results showed that all panels made from treated bagasse exceeded the EN standards for MOE, MOR, and IBS. However, WA and TS values decreased after ozone pretreatment compared to the un-treated (control) panels. Application of Duncan’s Multiple Range Test for the mean values of the results showed that the effects of both variables, except their interactions, on the mechanical and physical properties were highly significant (p ⩽ 0.01%). All the mechanical properties of the panels decreased when the treatment duration increased from 1 to 5 months.     

Effect of the carbon content on the magnetic and electric properties of thermally treated carbon steels and the possibilities of testing the quality of tempering of articles produced from them via the eddy-current method

The magnetic and electric characteristics of 4.7-, 2.2-, and 1.5-mm-thick hardened and tempered carbon-steel specimens with a carbon content of 0.35–1.02% have been studied. The relations of these characteristics to the carbon content, structure, and hardness of the studied specimens are analyzed. The structural state, the thickness, and the acceptable limits of the carbon-content variation in carbon-steel articles, properties that allow the quality of medium-temperature tempering to be tested with the use of the eddy-current method, have been determined.