Features of electromagnetic methods for testing the wear resistance of medium-carbon structural steel subjected to laser or bulk hardening and tempering

Features of applying attachable eddy-current transducers of two types (with a flat end surface and a protruding ferrite rod core with localities 5–6 and 3–4 mm in diameter, respectively) for testing the structural state, hardness, and abrasive wear resistance of structural steel 45X (0.45 mass % C and 0.85% Cr), which was hardened under the action of continuous laser radiation, have been studied. The feasibilities of the eddy-current and coercimetric techniques for evaluating the wear resistance of a medium-carbon steel subjected to laser or bulk hardening and tempering in the temperature range 75–600°C have been studied.     

Eddy-current control of the phase composition and hardness of metastable austenitic steel after different regimes of nanostructuring frictional treatment

The possibilities are studied for using an electromagnetic eddy-current technique of monitoring the phase composition and hardness of austenitic chromium–nickel steel that has been subjected to hardening frictional treatment in different technological regimes. It is shown that an eddy-current structuroscope and a Vektor eddy-current defectoscope make it possible to control the amount of straininduced martensite and the microhardness of the surface of metastable austenitic steel after nanostructuring frictional treatment with different numbers of gliding indenter scans (passes). The Vektor eddycurrent defectoscope allows one to monitor the phase composition of austenitic steel that has been subjected to nanostructuring frictional treatment in a temperature range from ?196 to +250°C.     

Eddy-current testing of the wear resistance of laser-hardened carburized chromonickel steel and the quality of laser hardening of drill bits

Features of eddy-current testing of carburized chromonickel steel 30XH3A subjected to processing with continuous laser radiation, subsequent treatment with cold at s-196°C (reducing the content of retained austenite in the carburized layer from 25–40 to 5–10 vol %), and tempering in the temperature range 100–400°C are studied. It is shown that the eddy-current method can be used to detect the presence of a laser-hardened wear-resistant layer on the steel surface and evaluate an abrupt decrease in the abrasive wear resistance of steel hardened with laser radiation, additionally treated with cold, and then exposed to low-temperature tempering. The possibility of eddy-current testing of the quality of laser hardening of roller paths of the bearing unit of rock-drilling bits manufactured from carburized steel 20XH3A using an attachable transducer with a protruding rod core is established.     

Eddy-current and coercive-force testing of abrasion-resistant ball bearing steel IIIX15 subjected to laser and bulk thermal processing

The possibility of using the eddy-current and coercive-force methods for assessment of the structural state and the abrasion resistance of ball-bearing steel IIIX15 (1.00% C and 1.42% Cr) is studied. The steel was subjected to laser and bulk quenching, subzero treatment, and tempering in the temperature range 75–600°C. The presence of residual austenite (in an amount of up to 45 vol %) in the quenched structure is shown to affect the sensitivity of the coercive-force and eddy-current methods used to test the abrasion resistance of steels tempered at low temperatures. Variations in hardness, abrasion resistance, and the parameter of the electromagnetic eddy-current testing as a function of the depth of the laser-irradiated zones in steel IIIX15 subjected to preliminary thermal strengthening is considered.     

Estimation of the quality of strengthening frictional treatment and subsequent tempering of eutectoid steel by the eddy-current method

The possibilities of the electromagnetic eddy-current method for evaluating the structural state and depth of strengthened layers on the surface of hardened and low-tempered steel U8 subjected to plastic straining using a hard-alloy indenter and subsequent heat treatment (tempering at T = 100–600°C) have been studied.     

Coercive-force and eddy-current testing of the abrasive wear resistance of quenched and tempered hypereutectoid carbon steels: II. Steels subjected to different quenching regimes,subzero treatment,and tempering after high-temperature quenching

The effects of the carbon concentration in martensite from 0.70 to 1.35 wt %, the presence of up to 70 vol % residual austenite, the degree of coagulation, and the volume fraction of tempering carbides on the specific features of the application of eddy-current and magnetic methods for testing abrasive wear resistance are studied. The case of high-carbon (0.83–1.53 wt % C) steels quenched from 790–1200° C, treated with cold at ?196°C, and tempered in the temperature range 75–700°C is considered.     

The influence of a combined strain-heat treatment on the features of electromagnetic testing of fatigue degradation of quenched constructional steel

The possibilities of the magnetic and eddy-current methods for testing fatigue degradation during low-cycle loading of quenched steel 50 (0.51% C) that was subjected to a combined strain-heat treatment according to an optimal regime that included friction treatment with subsequent tempering at T = 350°C, were investigated. It is shown that for steel that was subjected to a combined nanostructuring treatment, the accumulation of a plastic strain under “hard” cyclic loading can be tested using the coercimetric method and values of the residual magnetic induction on the major and minor magnetic-hysteresis loops, values of the maximum and initial magnetic permeabilities, and readings of an eddy-current instrument at a low excitation frequency of the eddy-current transducer. The appearance of surface fatigue cracks can be tested via eddy-current measurements at high frequencies, when the contribution of the crack formation in the hardened layer to the eddy-current characteristics is considerable.     

Influence of cryosoaking period on wear characteristics and surface topography of M35 tool steel

Cryogenic treatment affects tool steels wherein alteration in microstructural features like phases, uniform precipitation of carbides is observed. In this work, improvement in wear resistance of cryotreated material with microstructural features and surface roughness of material has been correlated. Samples of AISI M35 steel were hardened at 1200°C, followed by triple tempering at 555°C in the salt bath, subsequently subjected to cryogenic treatment at minus 185°C for varying cryosoaking period (4–32?h) followed by soft tempering at 100°C. Such samples were characterized for hardness, microstructure, carbide density, wear rate and surface roughness. A correlation of carbide density and roughness has been established with wear resistance.     

Inspection of the Strength Characteristics and Heat-Treatment Quality of Ferromagnetic Articles According to Parameters of the Residual-Magnetization Hysteresis Loop during Their Local Magnetization and Magnetization Reversal in a Pulsed Magnetic Field with a Variable Amplitude: III. Steel 50ΧΓΦΑ

Effects of the tempering temperature on specimens' hardness and on parameters of both the anomalous-hysteresis loop and the recovery curves for the gradient of the residual magnetization field's strength are studied experimentally. Test specimens made of steel 50XΓΦA intended for laminated springs are quenched in water from 850°C and subjected to local magnetization and magnetization reversal by a pulsed magnetic field created by an attachable solenoid whose axis is perpendicular to the surface. The amplitude of pulses changes with increment ΔH_p. Parameters enabling nondestructive testing of the hardness of multiple-leaf springs made from steel 50XΓΦA within three ranges of tempering-temperature variation (0–300, 300–600, and 0–600°C) are determined.     

Eddy-Current Evaluation of Wear Resistance of Case-Hardened Chromium–Nickel 20KhN3A Steel

The paper considers feasibility of eddy-current evaluation of the wear resistance of the quenched and tempered (100–400°C) case-hardened 20KhN3A steel under conditions of abrasive wear and sliding friction. The effect of cold processing on the susceptibility of the eddy-current method to the wear resistance of a hardened layer has been studied. The effect of the carbon content in the martensite prior to tempering over the range of 0.3 to 0.9 mass % on eddy-current measurements is discussed.     

Effect of microstructure and properties on the high temperature wear characteristics of 3Cr2W8V (H21) steel

The effects of microstructure on the high temperature wear characteristics of 3Cr2W8V steel, the high temperature wear mechanisms and the features of the worn surface have been investigated by means of a resistance-heating high temperature wear-testing device of our own design. It has been shown that the primary parameters affecting the high temperature wear behaviour of the material seem to be the precipitated carbides and austenite grain size in the microstructure, high temperature hardness and oxidation resistance of the material. The optimum high temperature wear resistance of the steel can be obtained by employing suitable quenching and tempering temperatures. The wear test temperature vs. wear value curves for this steel, heat treated using different heat treatment regimes, are similar in shape and different from each other in wear value. However, the wear mechanisms of this steel vary with temperature ranging from room temperature to 700 °C. Although in the range 400–700 °C all the scars are primarily composed of a number of grooves and varying degrees of built-up layered areas, the presence of these layered areas reduces the high temperature wear.     

The peculiarities of magnetic and eddy-current testing of quenched structural steel hardened by nanostructuring frictional treatment

This paper deals with the study of the potential of the magnetic and eddy-current methods for the assessment of the structural state of hardened wear-resistant layers on the surface of quenched medium-carbon structural steel 50 (0.51 wt % C) that is subjected to frictional treatment by a sliding hemispherical hard-alloy indenter. It is found that the presence of a thin ～220 μm hardened wear-resistant layer on the surface of quenched steel 50 can be verified by readings of an eddy-current instrument, as well as by values of the coercive force (for major and minor magnetic hysteresis loops) and the residual magnetic induction (for minor magnetic hysteresis loops if measurements are carried out in weak magnetic fields). The eddy-current method has the highest susceptibility to the structural transformations caused by frictional treatment.     

Severe-to-Mild Wear Transition of Titanium Alloys as a Function of Temperature

Dry sliding wear behaviors of Ti–6Al–4V and Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloys (code-named TC4 and TC11, respectively) against AISI 52100 steel under a load of 50–250 N at 25–600 °C were systematically investigated. For two titanium alloys, a severe-to-mild wear transition occurred with an increase in temperature. The critical transition temperatures of TC4 and TC11 alloys were 400 and 300 °C, respectively. Below the critical temperature, titanium alloys showed poor wear performance. As the temperature surpassed the critical temperature, the extremely low wear rates demonstrated excellent elevated-temperature wear performance of titanium alloys in the titanium alloy/steel tribo-system. The wear transition was characterized with the appearance of continuous, hard tribo-layer containing more oxides, especially Fe₂O₃, which showed a pronounced wear-reduced role. Adhesive and abrasive wear predominated in the severe wear regime; oxidative mild wear prevailed in the mild wear regime. Adhesive wear, abrasive wear and oxidative mild wear cooperated at the critical transition temperatures.     

热轧、低温回火态1250MPa级新型贝氏体耐磨钢板的组织和性能

研究了热轧、低温回火状态1250MPa级新型贝氏体耐磨钢板的组织和力学性能,测试了埋弧焊和CO2焊焊接接头的力学和机械加工性能。结果表明：轧态、低温回火耐磨板的组织由贝氏体铁素体和残余奥氏体组成,具有较高的力学性能、较高的回火抗力、良好的焊接性能和机械加工性能。     

High temperature friction and wear mechanism map for tool steel and boron steel tribopair

Abstract

Tribological systems working under severe conditions like high pressures, sliding velocities and temperatures are subjected to different phenomena such as wear, oxidation and changes in mechanical properties. In many cases, there are several mechanisms occurring simultaneously. The predominating type(s) of wear mechanism(s) presented will depend on the materials in contact, operating parameters and surrounding environment. In this work, high temperature tribological studies of boron steel sliding against tool steel were conducted using a pin-on-disc machine under unlubricated conditions at five different temperatures ranging from 25 to 400°C, three different loads: 25, 50 and 75 N (contact pressures of 2, 4 and 6 MPa respectively) and a sliding speed of 0·2 ms^?1. Scanning electron microscopy/energy dispersive spectroscopy and X-ray techniques were used for analysing the resulting damage and tribolayers of the worn surfaces. Additionally, hardness measurements were carried out in a special hot hardness rig in the same temperature range as that used in pin-on-disc tests. The results have shown that for a given load, the wear rate of boron steel decreased as the temperature increased, reaching its lowest value at 400°C at 50 N. In the case of the tool steel, it could be observed that at 200°C and above, the wear rate decreased as the load increased. This behaviour is consistent with the formation of a protective oxidised layer initiated at 100°C. At higher temperatures, such layers become more pronounced. The obtained data were finally used to construct a friction and wear mechanism map for this material pair that takes temperature and pressure into account.     

Tribological properties of nanostructured DLC coatings deposited by C60 ion beam

The frictional and wear characteristics of nanostructured DLC films were investigated. The coatings were deposited on silicon substrates by irradiation of a mass-separated C₆₀ ion beam with 5 keV of energy and a deposition temperature ranging from 100 to 450 °C. The effects of deposition temperature on the surface morphology, nano-structure, mechanical properties and tribological characteristics of the coatings were assessed. Results showed that deposition temperature strongly affects the nanostructure and surface morphology of the coatings. Coatings deposited at temperatures exceeding 350–400 °C exhibited an increase in surface roughness as well as compressive stress due to the formation of graphite, which led to a significant increase in the friction coefficient and wear rate. Coatings deposited at 300 °C showed the best tribological properties.     

Magnetic and electromagnetic inspection of mechanical properties of high-carbon steel with an initial fine-pearlite structure subjected to high-temperature annealing

We study the possibilities of applying the measurements of major and minor magnetic hysteresis loops and electrical and eddy-current parameters for estimating changes in the strength and plastic characteristics of the high-carbon steel У 10 (with 1.03 wt % C) with a fine-pearlite structure during annealing at 650°C for 10–300 min. We analyze the correlations between the mechanical and physical properties of this steel with pearlite structures differing in morphology and imperfection of cementite, as well as the levels of solid-solution hardening and microdistortions of the ferrite-component lattice.     

Possibilities of Nondestructive Testing of Physico-Mechanical Characteristics of Hypereutectoid Carbon Steels with the Structures of Isothermal Austenite Decomposition

The possibilities of estimating the hardness, the wear resistance under abrasive action and sliding friction, the impact strength, and the internal stresses of the U9 steel (with 0.94% of carbon) with the initial fine-lamellar pearlite structure annealed at 650°C during 2–600 min on the basis of magnetic and electrical characteristics, readings of an eddy-current instrument, and parameters of electromagnetic-acoustic conversion are studied. A comparative analysis of the magnetic, electromagnetic, strength, and tribological characteristics of the U10 and U15 hypereutectoid steels (with 1% and 1.53% of carbon, respectively) subjected both to isothermal treatment at 330–650°C (with formation of pearlite and bainite structures) and to additional short-time annealing at 650°C is carried out.     

Effect of Heat Treatment Temperature on Microstructure and Mechanical and Tribological Properties of Cold Sprayed Ti-6Al-4V Coatings

In this study, Ti-6Al-4V (Ti-64) coatings were prepared on commercial Ti-64 substrates via a high-pressure cold spray process. The coatings were heat treated at different temperatures of 400–1000°C to investigate the effect of heat treatment temperature on their microstructure and mechanical and tribological properties. The increased heat treatment temperature from 400 to 600°C promoted diffusion between sprayed Ti-64 particles. Recrystallization of the sprayed particles was found at the heat treatment temperature of 800°C and grain growth was found in the microstructure of the coating heat treated at 1000°C. The highest and lowest hardnesses of the heat-treated coatings were found at heat treatment temperatures of 400 and 800°C, respectively. Therefore, the lowest and highest specific wear rates of the coatings were consistently found at 400 and 800°C due to their highest and lowest abrasive wear resistances associated with their highest and lowest surface hardnesses, respectively. The coating heat treated at 400°C showed the highest surface hardness of 470.1 Hv and lowest specific wear rate of 69.6 × 10^?14 m³/Nm. It could be concluded that the microstructure and mechanical and tribological properties of the Ti-64 coatings were significantly influenced by heat treatment temperature.     

Effect of technological parameters on microstructure and accuracy of B1500HS steel parts in the hot blanking

Hot blanking process could be used for producing diverse fine blanking parts with comprehensive mechanical properties and to solve the problems in the piercing and trimming of press-hardened parts. To explore the optimal hot blanking process and evaluate the effects of some technological parameters on the phase transformation, fracture quality, and dimensional accuracy of the parts, several different blanking temperatures (450–800 °C) and die clearances (8–25%) were used in the hot blanking of B1500HS steel. The experimental results show that as the blanking temperature increases at a certain die clearance, the dimensional accuracy shows a trend of “negative growth–positive growth–negative growth,” and a higher dimensional accuracy of blanked parts can be attained at blanking temperatures 450–500, 600–650, or 750–800 °C. Besides, the burnish zone width increases, and the burnish and rollover zone widths account for ~?80% of the steel sheet thickness at 800 °C. At blanking temperatures 650–800 °C, the microstructure of blanked parts is completely martensite, the microhardness of parts is ~?550 HV, and the perpendicularity of fracture increases as the blanking temperature increases. Parts with a high-dimensional accuracy, better fracture perpendicularity, wide burnish zone, better mechanical properties, and wear resistance can be obtained at blanking temperatures 750–800 °C.