Induction Hardening Research Articles

The Design of a System for the Induction Hardening of Steels Using Simulation Parameters

This paper presents the development of a piece of induction hardening equipment based on the foundations of the design, starting from zero. It was intended for steels in general, and was tested on unalloyed low- and medium-carbon steels, whereas the results for EN 1C60 steel are shown in this study. The EN 1C60 steel showed average results, and was chosen as a representative of a wider group of engineering steels. The main objective of this work was to develop a flexible system for mild steel hardening that can be used for various hardening depths and steel types. The system design’s priorities were the use of standard electronic components to avoid supply chain disruptions and to achieve high energy efficiency. The construction of the prototype in full detail is also presented. The optimal process parameters are listed, as well as the procedure of their obtaining by using the appropriate simulation method. The key parameters were adjusted in consecutive steps. This study resulted in high matching between the model predictions and experimental results. The basic goal of this research was achieved, with the system having a minimum energy efficiency of 75.3%, a most frequent energy efficiency of 90% and a maximum energy efficiency of 95.1%.

Innovative technologies for strengthening of internal surfaces of suspension parts of heavy-loaded machines by laser and high-frequency induction methods

In the article innovative methods of surface hardening of internal surfaces of machine parts by laser and highfrequency induction heating are presented. The relevance of applying the methods of laser and induction hardening for the internal surfaces of heavily loaded parts of quarry equipment is proved. The results of modeling and calculation of thermal and electromagnetic fields under the influence of an external electromagnetic field and laser radiation beams are presented. The original design of a complex of equipment for processing the internal surfaces of suspension parts by external electromagnetic field is described. The optimal designs of inductors with magnetic circuits made of various materials are shown. The study of the structure and properties obtained on the internal surfaces of heavily loaded suspension parts of cars, line of the BelAZ company, treated according to the optimal modes of surface induction exposure is given. The developed original technology and equipment of laser surface hardening, which makes it possible to increase the wear resistance of heavily loaded parts, is described. Data on the implementation of research results at JSC “BELAZ” – the Management Company of the Holding “BELAZ-HOLDING” for processing a wide range of heavily loaded suspension parts are given.

Study on induction hardening performance of 34CrNi3MoA steel crankshaft

The evolution of the temperature field, microstructure field, and residual stress field of a 34CrNi3MoA steel marine diesel engine crankshaft during medium-frequency induction hardening was studied based on an electromagnetic-thermal-transformation-stress coupled numerical model, which considers the effect of internal stress induced by transformation induced plasticity on residual stress. Using the equal conversion rate method, the austenitizing region of the crankshaft was determined during the induction heating stage. In the quenching stage, the parameters of the phase transformation model are derived from the continuous heating expansion curve and the continuous cooling transformation curve, and the phase transformation kinetics equation is used to analyze the phase transformation process of the crankshaft. The results indicate that extending the heating time can enhance the uniformity of the surface temperature of the crankshaft and the thickness of the hardened layer. The simulation results are validated by measurements of hardened layer, hardness and residual stress, and the simulation results are in good agreement with the experimental results.

Explaining hardness modeling with XAI of C45 steel spur-gear induction hardening

Explaining hardness modeling with XAI of C45 steel spur-gear induction hardening

Evolutionary Optimizing Process Parameters in the Induction Hardening of Rack Bar by Response Surface Methodology and Desirability Function Approach under Industrial Conditions.

Conditions of industrial production introduce additional complexities while attempting to solve optimization problems of material technology processes. The complexity of the physics of such processes and the uncertainties arising from the natural variability of material parameters and the occurrence of disturbances make modeling based on first principles and modern computational methods difficult and even impossible. In particular, this applies to designing material processes considering their quality criteria. This paper shows the optimization of the rack bar induction hardening operation using the response surface methodology approach and the desirability function. The industrial conditions impose additional constraints on time, cost and implementation of experimental plans, so constructing empirical models is more complicated than in laboratory conditions. The empirical models of nine system responses were identified and used to construct a desirability function using expert knowledge to describe the quality requirements of the hardening operation. An analysis of the hypersurface of the desirability function is presented, and the impossibility of using classical gradient algorithms during optimization is empirically established. An evolutionary strategy in the form of a floating-point encoded genetic algorithm was used, which exhibits a non-zero probability of obtaining a global extremum and is a gradient-free method. Confirmation experiments show the improvement of the process quality using introduced measures.

Investigation of combined surface treatments and coatings to increase the wear behavior of heat treatable steels

A combination treatment of nitriding and induction hardening can achieve high hardness depths in short treatment times and can therefore be seen as an alternative to deep nitriding. However, the compound layer, which makes a significant contribution to the wear resistance of nitrided components, decomposes during the induction heat treatment of the nitrided part. Therefore, the tribological behavior of parts processed this way is affected. In the present work, the wear behavior of surface layers resulting from combined heat treatment of EN42CrMo4 and PVD a-C:H(:Si) coating is investigated and evaluated. For the wear testing, a two-disk test rig was used. The wear was determined gravimetrically and by optical evaluation of the wear tracks. It was found, that the wear resistance of the investigated heat-treatable steel can be improved by duplex surface treatments such as nitriding and induction hardening as well as nitriding and PVD a-C:H(:Si) coating compared to the heat treated-only condition. By triplex treatment, no further improvement of the wear resistance could be observed.

How inadequate heat treatment or complete lack thereof can cause component failures

Abstract This paper is a compilation of failure analysis case studies exploring the subject of inadequate heat treatment. As with other papers in this series, the presented failure cases are rather simple and may appear trivial to the experienced failure analyst. The authors can guarantee however, that minor heat treatment errors are committed easily and have a considerable damage potential which may entail heavy financial losses. Therefore, cases of inadequate heat treatment or a complete lack of necessary heat treatment belong by all means in the column Failure Analysis. The metallurgical subject of these failure cases are low-alloy hardenable steels without exception. Common heat treatment processes such as induction hardening, case hardening, nitriding as well as through-hardening and tempering will be touched upon.

Failure analysis of ball screw in the progressive induction hardening and finishing machining

Some failure modes, such as wear, quenching and finishing cracks, are easy to produce on the surface of the ball screw during the progressive induction hardening, and can shorten the fatigue life of ball screw. The hardened layer, microstructure, tensile strength and cracks of a 55CrMo steel ball screw after induction hardening are tested or observed by experiment. Based on the results of experiment and numerical simulation, the effect of heating temperature on the austenitization, microstructure, tensile strength, grain size of austenite and stress state of the ball screw are analyzed and discussed. In the induction hardening process, high heating temperature can result in some problems such as coarse grains and melting of the eutectic Fe-FeS-MnS produced on the grain boundary, which will impact the quenching quality and service performance of ball screw. Before the phase transformation of austenite transformed to martensite, the channel top of ball screw is in the state of three-dimensional tensile stress, which leads to brittle fracture during the cooling process. In the cutting process, the mechanical and thermal stress successively generate the tensile stress in the inner and outer layers of the ball screw channel, resulting in the internal cracks formed during quenching gradually extending to the surface. The essential cause of cracks in the finishing of the ball screw is the cracks formed during the induction hardening.

Mechanical Properties Comparison Between Induction Hardening and Rehardening of <i>Axle Shaft</i> AISI 1043 According to JIS G 0559 Standard

Induction hardening is carried out to increase the hardness of the axle shaft surface. Axle shaft specimens were hardened from the bearing seat area to the spline area of the axle. The hardness requirements of the scope of the shaft met 400-450 HV of the JIS G 0559 standard. The axle shaft's hardening process with induction coil stops in the field before reaching the spline area. It causes the hardness becomes uneven and not comply with the standard. The re-hardening process is often carried out to repair rejected parts. In this work, the result of the re-hardening process is analyzed and compared with the first hardening process—the analysis focus on mechanical properties such as static test (torque test), fatigue testing, and hardness. Microstructures were used to verify the result of the process. The results showed that the results of re-hardening can meet the expected qualifications. The difference in breaking torque (static test) values ​​is 4,428.155 Nm for hardening specimens and 4,287.832 Nm for re-hardening with a standard torque of 4,000.000 Nm, all samples fractured in the spline area. High fatigue values ​​were obtained from the hardening results, with 216,265 cycles and 252,224 cycles for re-hardening. The results of the re-hardening hardness test obtained from Vickers are higher than the hardening results. The results of microstructural testing in both hardening processes contained ferrite and Fe3C on the surface and for the core consisting of ferrite and pearlite. Based on the analysis, the re-hardening process has no significant effect compared with the hardening results. Therefore, in this case, the re-hardening process can be used to fix the failed part.

Crankshaft Hardness Quality Evaluation of Passenger Car

A crankshaft is a part of the main engine components and plays a critical role in car performance. The crankshaft component consists of journals, pins, and flange that experience induction hardening treatment to increase their hardness. Hardness case depth represents important hardness criteria achieved by the depth of induction hardening process. This paper aims to evaluate crankshaft hardness quality by analyzing hardness case depth measurement. The control chart shows the results, which presents process stability to indicate abnormal processes. The capability process is also performed to process consideration. Evaluation results show hardness case depth is not at its best performance even though process capability meets product requirements. Affected factors to process stability are manpower, method, material, measurement, machine and environment. Implemented improvements based on the problem root cause to eliminate influenced factors and achieve stable process are delivered.

The effect of gradient order on impact toughness of carbon S38C axle steels with induction hardening

Induction hardened S38C axles exhibit the balance between good crack growth resistance at the body and wear resistance at the wheel seat, which can be physically attributed to the gradient structure with fine grains (FG) near the surface and coarse grains inside the base metal (BM). However, the impact toughness of such bulk gradient engineering structure is less reported particularlly when experiencing high-speed impacts. Therefore, the impact behaviors of the S38C steel are thoroughly examined by using the V-notch instrumented Charpy impact testing in this work. It is clearly found that the gradient order has a significant effect on the impact response. For the gradient structure termed as FG → BM, the absorbed energy is significantly lower than the BM structure but the higher strength and hardness, which indicates that the FG → BM structure is difficult to tailor the fatigue crack growth and the resulting fatigue life of railway axles. By contrast, the BM → FG structure exhibits more excellent impact resistance primarily owing to the micropore coalescence. To acquire the exceptional damage tolerance, the inner bore and external surface of the S38C axles can be sequentially strengthened to acquire an integrated gradient structure.

Determination of Machining Parameters for a Specific Adjustment of the Residual Stress Profile by Induction Hardening*

Abstract Within the research work of the Transregional Collaborative Research Center TRR 136, process signatures were determined for processes that generate essentially thermal loading of the component surface layer. These process signatures represent correlations between material modifications (e. g. changes of residual stress, microstructure, hardness profile, etc.) and characteristic values of the material loading. The underlying idea is that the material does not know any processes but only loads caused by processes. In particular, the same loads lead to the same material modifications regardless of the kind of process. A decisive advantage of this concept over conventional approaches is the possibility of calculating the necessary internal material loads backwards on the basis of concrete specifications for the material modifications. If there are additional correlations between internal material loads and process quantities as well as between process quantities and machining parameters, the necessary machining parameters can be determined, too. In this paper, this procedure will be introduced using the example of one-sided induction hardening of cuboidal components made of 42CrMo4. The determination of the process signature by experimental and numerical investigations is described and work for experimental verifications are presented.

A Study on Very High Cycle Fatigue Properties of Axle Steel with Induction Hardening on the Surface

Rotating bending fatigue tests were performed to investigate the effect of induction hardening (HQI) on the very high cycle fatigue (VHCF) properties of the axle steel. In addition, finite element analyses (FEA) and scanning electron microscope (SEM) observations were conducted to elucidate the fundamental behavior. The results obtained are summarized as follows; (1) It was found that the fatigue strength of the axle steel was improved by almost 300 MPa in VHCF region by HQI, (2) A lot of specimens of the HQI had fractured in VHCF region, therefore, the consideration of VHCF properties should be taken into account in the design of railway axles, (3) Crack initiation sites can be classified into three forms; the surface of the HQI layer in the minimum section, the base metal beyond the HQI layer in the axial direction, and the internal base material in the minimum section. These can be reconfirmed through the comparison between the local fatigue strength distribution and the bending stress distribution obtained by FEA.

Investigation of induction hardening on heat-treated EN8 steel by alternately timed quenching process

EN8 steel is mostly used for high-strength applications such as axles and crankshafts in vehicles, as well as nuts, gears, and studs. In this work, numerous pre-heat treatments such as annealing, normalizing, hardening, and tempering were performed on EN8 steel. Following the completion of all pre-heat treatment steps, the samples are surface hardened by induction hardening with an alternatively timed quenching approach. A Vicker hardness testing equipment was used to determine the surface hardness of pre-heat treated induction hardening samples. The results show that the normalizing with hardening and tempering sample has a greater surface hardness than the normalized and annealed samples. On the induction hardening samples, case depth was also assessed. The microstructure of the surface hardened samples were examined using an optical microscope. The normalizing with hardening and tempering sample has the highest grain size numbers and martensite needle size.

Comparison of the surface morphologies of ceramic reinforced metal matrix composite cams after wear tests under dry and wet conditions

The integral engine parts, such as camshaft members, are usually not preferably made of ceramic-reinforced MMC because the margin of compromise on the engine performance is small. However, the lightweight and wear-resistant nature of the mentioned materials can benefit fuel consumption without necessarily compromising engine performance. In this study, Al (AA2124) matrix is reinforced with ceramic particles of two different types (SiC, B4C), size distributions (B4C: 1–7, SiC: 2 and 20 μm), and volume fractions (0, 10, 20, 30 vol.%) to manufacture camshaft cams (lobes). While MMC cams are manufactured by powder metallurgy (300 MPa, 615°C, 30 minutes), spherical graphite cast iron (GGG40) cams are prepared by casting, induction hardening, and machining. The wear behavior of MMC cams is compared with the reference unreinforced AA2124 and conventionally used cast iron cams under dry and virtually created engine-like wet conditions. It was attempted to correlate the percentage increase in the roughness and weight loss with the structure of the cams using SEM, EDX, and macroscopy analysis. Results showed that the initiation of a three-body abrasive wear mechanism for 30 vol.% of the larger SiC particles caused lower wear resistance in the cams under dry conditions. As for the wet conditions, although the cams’ wear resistance increased with increasing ceramic particles’ content, it resulted in enhanced wear in the counterface when larger ceramic particles were used as reinforcement. Overall, higher ceramic content and larger particle size encourage three-body abrasive wear between the interacting surfaces and assist in degraded wear resistance under wet conditions.

Usage of continuous cooling transformation (CCT) diagrams for laser and small-scale induction hardening

Using standard continuous cooling transform (CCT) diagrams for finding hardness of surfaces obtained by laser or small-size induction hardening is discussed. Their misuse may lead to differences between the values obtained from the model and experimental data because unlike hardening of large surfaces, the produced heat is mostly transferred away not by convection to the environment, but mainly by conduction to the interior of the metal material at a very high rate (at the level of many hundred Kelvins per second). The paper explains the details and offers a methodology of suppressing errors based on a combination of theoretical and experimental approaches. The methodology is illustrated with an example.

Morphology, properties and stress-strain state of carburized gear made of steel 12KhN3A after high-frequency currents quenching

The results of the study of the effect of cementation with subsequent induction quenching by high-frequency currents on the physical properties of a gear made of 12HN3A steel are presented, the influence of technological factors (temperature and time) on the cementation layer is studied. The study was carried out using a well-known pasty carbonatesoot carburetor and in a pasty carburetor with composition optimization through the synthesis of a di-ammonium salt of 2-monoethanolamine and citric acid, in terms of carbon saturation activity of steel not inferior to melts of cyanide salts. The structure and chemical composition of 12HN3A steel before and after cementation were studied. In the course of the work, the following mode of chemical-thermal treatment of 12HN3A steel was used: cementation due to exposure to highfrequency currents temperature T = 960 °C, medium — air; induction hardening due to exposure to high-frequency currents temperature T = 860 °C, medium — aqueous solution, tempering low temperature T = 190 °C, medium — aqueous a solution that provides an increase in the margin coefficient for fatigue strength to 86.1 MPa and yield strength to 820 MPa while maintaining a sufficient level of plastic properties. The stress-strain state of a gear wheel made of 12HN3A steel is estimated before and after cementation of its working surfaces with subsequent induction hardening by high-frequency currents.

Investigating the Effects of Advanced Heat Treatment Techniques on the Mechanical Properties of Cast Components

This paper presents a comprehensive investigation into the effects of advanced heat treatment techniques on the mechanical properties of cast components. The study employs cutting-edge methodologies, including induction hardening, laser hardening, and cryogenic treatment, to modify the microstructure of various cast alloys. The primary focus is on the impact of these treatments on the hardness, tensile strength, ductility, and fatigue resistance of the materials. The experimental results reveal a significant enhancement in the mechanical properties of the treated components, with notable improvements in wear resistance and structural integrity. The findings also underscore the potential of these advanced heat treatment techniques in extending the service life of cast components, thereby contributing to the sustainability of mechanical systems. This research provides a novel perspective on the optimization of heat treatment processes, offering valuable insights for the design and manufacturing sectors. The outcomes of this study have far-reaching implications for industries that rely heavily on cast components, including automotive, aerospace, and heavy machinery, and pave the way for future research in this critical area of mechanical engineering.

Predictive Modeling of Induction-Hardened Depth Based on the Barkhausen Noise Signal.

A non-destructive verification method was explored in this work using the Barkhausen noise (BN) method for induction hardening depth measurements. The motive was to investigate the correlation between the hardness depth, microstructure, and the Barkhausen noise signal for an induction hardening process. Steel samples of grade C45 were induction-hardened to generate different hardness depths. Two sets of samples were produced in two different induction hardening equipment for generating the model and verification. The produced samples were evaluated by BN measurements followed by destructive verification of the material properties. The results show great potential for the several BN parameters, especially the magnetic voltage sweep slope signal, which has strong correlation with the hardening depth to depth of 4.5 mm. These results were further used to develop a multivariate predictive model to assess the hardness depth to 7 mm, which was validated on an additional dataset that was holdout from the model training.

INVESTIGATION OF THE DISTRIBUTION OF RESIDUAL STRESSES IN THE ZONE OF THE WELDED SEAM OF RAILS OF THE R65 TYPE OF THE DT350 CATEGORY

Rails are the most important element of the superstructure of the railway track. To increase the smoothness of the ride, reduce dynamic loads at the junctions of the rails, contact welding of rails in a whip in stationary conditions and aluminothermic welding directly on the way are becoming more common. Despite the improvement in the quality of the joints, the zone of welded joints, due to a change in the structure due to the physical processes of welding and heat treatment, is still a place with lower mechanical characteristics compared to the metal of solid- rolled rails. The development of defects in welded butt joints is one of the main reasons for removing rails from service. An important component of ensuring the quality of rails and welded joints is the formation of a favorable diagram of residual stresses. In order to assess the effect of induction heating and hardening, a study was made of the distribution of residual stresses before and after heat treatment of the welded joint, full-profile samples of R65 type rails of the DT350 category of steel grade E76HF, the current production of EVRAZ ZSMK JSC. It has been established that compressive residual stresses predominate in the rail head both before and after heat treatment,heating reduces the overall stress level to the level of 210–264MPa, the maximum compressive stress level equal to 586 MPa is fixed at joint No. 224, after hardening heat treatment. Tensile stresses predominate in the neck of the rail, a sharp increase in stresses after hardening heat treatment was noted, the stress level increased more than three times, from 68 MPa to 254 MPa. After heating the welded joint, a slight decrease in residual stresses in this area is observed. Compressive stresses are recorded in the rail sole, with identical diagram, regardless of heat treatment. A minimum of stress is fixed in the center of the sole, with a subsequent increase towards the edge of the feather. The greatest difference was recorded after hardening heat treatment, from 57MPa to 537MPa, respectively.