Bearing Steel 100Cr6 Research Articles

Influence of Lubricated Rolling/Sliding Tribotesting on Hydrogen Trapping in 100Cr6 Bearing Steel

As hydrogen reduces the fatigue life of 100Cr6 bearing steel significantly, extensive research on the interaction of hydrogen with 100Cr6 is necessary. This study investigated the influence of rolling/sliding tribotesting performed on a micro-pitting-rig on the hydrogen absorption and trapping behaviour of 100Cr6 bearing steel. Thermal desorption mass spectrometry was used to compare the hydrogen desorption spectra of 100Cr6 samples after tribological tests and static heated oil-immersion tests to untested reference samples. The approach was chosen to further understand the influence of both microstructural deformation as well as steel-oil contact on the hydrogen absorption and trapping behaviour of 100Cr6. The tribological test showed a stable friction behaviour and mild wear which was dominated by local plastic deformation of surface asperities. Despite the mild wear, a change in de-trapping temperatures was found for tribotested samples compared to oil-immersed and untested reference samples. This finding indicates that even mild tribotesting conditions alter the hydrogen trapping behaviour of 100Cr6 bearing steel.

Evaluation of the effects of the application of Ti−C:H DLC coatings obtained by PVD techniques in the kinematic pairs of internal combustion engines and powertrain systems.

The article attempts to analyze the possible effects of using Ti−C:H DLC carbon coatings produced by pulsed magnetron sputtering (PVD) to reduce friction coefficient and wear in kinematic pairs found in internal combustion engines and powertrain systems used in automotive vehicles. The aim of such action is primarily to reduce internal losses in the aforementioned units. The coatings were deposited on heat-treated bearing steel 100Cr6, examined using a scanning electron microscope FEI Quanta 200 Mark II with the chemical analyzer EDS EDAX Genesis XM 2i, tribotester T−01M examining the friction coefficient in the ball-disc correlation and Hommel Werke T8000 profilometers, additionally, in order to check the coating thickness, studies were carried out using the Calotest method. The results obtained indicate that both the friction coefficient and wear are drastically reduced in relation to samples on which no DLC coatings were applied.

VHCF behavior and defect tolerance of modified bainitic 100Cr6 with a high retained austenite content

Since the fatigue life of high strength steels, e.g., roller bearing steel 100Cr6, depends on microstructural defects, an improvement of their defect tolerance can enhance the performance of components. To improve the defect tolerance, the retained austenite content can be increased. Thus, in this work the high cycle and very high cycle fatigue behavior of two modified laboratory variants of 100Cr6, which have an increased content (1.5 wt%) of Al and Si, respectively, were analyzed since these alloying elements lead to higher fractions of austenite. Moreover, an industrially available variant with 0.6 wt% Si was analyzed as a reference. All steels were investigated in the bainitic condition and had austenite contents of about 20 vol-%. However, the distribution and chemical composition of the austenite differed. The presented results demonstrate that the effect of retained austenite on defect tolerance is caused by i) the increased ductility and ii) the local deformation-induced phase transformation. To strengthen the effects of the austenitic phase, a finer distribution as well as a lower austenite stability are useful. Consequently, to evaluate the effect of retained austenite on the fatigue behavior the content, the distribution and the chemical composition of the austenitic phase must be considered.

Effect of 160 MeV Xenon Ion Irradiation on the Tribological Properties and Crystal Structure of 100Cr6 Bearing Steel.

This is the first study ever to show the impact of high-energy 160 MeV xenon ion irradiation on the properties of 100Cr6 bearing steel. The projected range (Rp) of xenon ions is 8.2 µm. Fluence-dependent variations in the coefficient of friction and wear of the 100Cr6 steel material have been observed. These changes correlate with shifts in the crystal lattice constant and variations in the oxygen, carbon, and iron content in the wear track. Fluence-dependent changes in these parameters have been observed for the first time. Irradiation reduces stresses in the crystal lattice, leading to crystallite size increase. The modifications in the properties of 100Cr6 steel result from radiation-induced defects caused by electronic ion stopping. The degree of these modifications depends on the applied irradiation fluence. Furthermore, the use of a higher irradiation fluence value appears to mitigate the effects produced by a lower fluence.

Experimental Investigation of the Effect of Deep Cryogenic Treatment of 100Cr6 Bearing Steel

Experimental Investigation of the Effect of Deep Cryogenic Treatment of 100Cr6 Bearing Steel

Microbiologically influenced corrosion of a novel pipeline steel containing Cu and Cr elements in the presence of Desulfovibrio vulgaris Hildenborough

Inspired by the principle of copper-containing antibacterial stainless steel, a new type of Cu-Cr-bearing pipeline steel has been developed. Through a variety of surface characterization and electrochemical tests, the antibacterial property and microbiologically influenced corrosion resistance (MIC) of the novel type of steel were studied. Although the addition of Cu did not make this steel exhibit ideal antibacterial properties, all the results still showed that MIC resistance of the novel pipeline steel was better than that of X70 and Cr-bearing steels. The synergistic effect of Cr and Cu in the Cu-Cr-bearing pipeline steel contributed a beneficial effect to the improved MIC resistance.

Effect of retained austenite on the fatigue behavior of modified bainitic 100Cr6 steels considering local phase transformation

Since highly loaded components, such as roller bearings, tend to have relatively high lifetime scatter caused by microstructural defects, an increased defect tolerance of the material can improve the performance as well as the reliability of these highly stressed components. To increase the defect tolerance of the roller bearing steel 100Cr6, two different laboratory melts with either 1.5 wt.-% Al or 1.5 wt.-% Si in addition to the standard composition were developed. After an adapted heat treatment, both steels exhibited a bainitic microstructure with a relatively high content of retained austenite with more than 20 vol.-%. Considering the effects of the retained austenite, a defined mechanical stability is essential to avoid excessive deformation-induced transformation from the retained austenite into α′-martensite, which can lead to shape deviations in components. However, besides the increased deformability of the austenitic phase, local phase transformations in the vicinity of defects can increase the defect tolerance. The fatigue tests performed at ambient temperature (AT) and at T = 100 °C, show a higher fatigue strength of the Si-alloyed steel due to a refined microstructure and revealed for both steels a relatively high austenite stability, since no macroscopic phase transformation was observed. The high austenite stability can be explained by a relatively high carbon content of the austenitic phase. However, in contrast to the Al-alloyed steel, a decrease in the fatigue strength and in the defect tolerance due to the increased temperature were observed for the Si-alloyed steel, which indicates a more pronounced phase transformation at AT. The lower carbon content and the finer distribution of the retained austenite, when compared to the Al-alloyed steel, are supposed to be the reason. While a smaller carbon content decreases the phase stability, the refined austenite distribution results in a higher probability of retained austenite presence in the vicinity of a defect.

Effect of Heat Treatment on the Passive Film and Depassivation Behavior of Cr-Bearing Steel Reinforcement in an Alkaline Environment

Using Cr-bearing low-alloy steel is an effective preventive measure for marine structures, as it offers superior corrosion resistance when compared to plain carbon steel. However, it remains unclear how quenching and tempering heat treatment, which is commonly applied to steel reinforcement in some specific environments to improve its mechanical properties, affects its corrosion resistance. In the present work, the impact of heat treatment on the passive film and depassivation behavior of the 0.2C-1.4Mn-0.6Si-5Cr steel are studied. The results reveal that quenching and tempering result in grain refinement of the Cr-bearing steel, which increases its hardness. However, this refinement causes significant degradation in its corrosion resistance. The critical [Cl−]/[OH−] ratio after quenching and tempering is determined to be approximately 6.6 times lower than that after normalization, and the corrosion rate is 1.6 times higher. After quenching and tempering, the passive film predominantly comprises iron oxides and hydroxides, with relatively high water content and defect density. Additionally, the FeII/FeIII ratio and film resistance are relatively low. In comparison, after normalization, the steel exhibits high corrosion resistance, with the passive film formed offering the highest level of protection.

CHARACTERISATION OF MICROMECHANICALAND TRIBOLOGICAL PROPERTIES OF TITANIUM GRADE 2AFTER CYCLIC OXIDATION

This paper presents the characterisation of micromechanical and tribological properties of titanium Grade2 before and after cyclic oxidation. The oxidation process was carried out at temperatures of 600C, 650Cand 700C in 4 and 12 cycles. Microscopic studies showed that oxide particle size increased with increasingoxidation temperature and the number of cycles. Titanium Grade 2 showed up to 3 times higher hardnessafter cyclic oxidation. The highest hardness (8.4 GPa) was obtained after 12 cycles of titanium oxidation at650C. Tribological tests were conducted in pairs with different materials (Al2O3, ZrO2, bearing steel 100Cr6).The presence of oxide layers obtained on the titanium surface resulted in a significant reduction in specificwear rate. Titanium Grade 2 showed the best resistance to sliding wear after cyclic oxidation at 600C duringsliding interaction with ZrO2 and 100Cr6 balls (unmeasurable wear under assumed test conditions). In theother test variants, the reduction in wear ranged from 37 to 96%.

Integrity Study of the Machined Surface Quality in Hard Turning

Since their appearance, machining techniques have undergone multiple improvements. The processes of shaping materials by removing material have been constantly questioned in order to stay in step with industrial requirements, whatever economic or ecological. Today, the manufacturing engineer must therefore be able to answer a multitude of questions in order to quickly produce parts of the required quality and at low cost. Hard turning is a process that can be described as standard in a number of sectors such as the production of bearing steel 100Cr6 chrome with a hardness of 62 RC, but also turning auto parts steel chromium-manganese cemented hardened gears as 27MnCr5 a hardness of 62 RC. The technical and economic feasibility of machining parts such harshness was made possible thanks to the use of new tool materials with a very high hardness and high chemical stability at high temperatures, such as cubic boron nitride CBN, and with the arrival of new machine tools with significant stability and high precision. Hard turning allows today to produce high-quality surfaces from competing in many cases, operations traditionally reserved for rectification. High speed machining has also showed its competitiveness in applications such as turning parts for gearboxes and drivesystems in hardened materials. This article is a contribution to the study of the integrity of the machined surface in hard turning.

Study of Residual Stresses and Austenite Gradients in the Surface after Hard Turning as a Function of Flank Wear and Cutting Speed.

This paper investigates the influence of cutting speed and flank wear on the depth profile of residual stresses, as well as the fraction of retained austenite after hard turning of quenched bearing steel 100Cr6. Residual stress and retained austenite profiles were studied for the white layer, heat-affected zone thickness, and XRD sensing depth. It was found that the influence of flank wear on the white layer and heat-affected zone thickness predominates. On the other hand, residual stresses are affected the cutting speed and the superimposing contribution of flank wear. Moreover, these aspects also alter microhardness in the affected regions. The study also demonstrates that information concerning residual stresses and the austenite fraction is integrated into the white layer, and the heat-affected zone in the surface is produced by the insert of low flank wear since the XRD sensing depth is more than the thickness of the white layer. On the other hand, the pure contribution of the white layer or the heat-affected zone to residual stress and the austenite fraction can be investigated when the affected surface region is thick enough.

Porovnanie geometrickej presnosti obrobkov po tvrdom frézovaní a brúsení

This paper deals with surface integrity after hard milling of bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear. Non homogeneity of cutting force distribution within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that the shape as well as structure remarkable non homogeneity should be expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand, the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

Very high cycle fatigue of high carbon chromium bearing steel at high compressive mean stresses

Very high cycle fatigue (VHCF) of high carbon chromium bearing steel 100Cr6 (SAE52100; JISSUJ2) is investigated with ultrasonic fatigue testing for compressive mean stresses with minimum stresses σmin at compressive yield stress σCY, for σmin = 0.59σCY, and for load ratio R = −1. Fatigue limits are found for σmin = σCY and for σmin = 0.59σCY, whereas no fatigue limit below 109 cycles exists at R = −1. Cracks leading to VHCF failures exclusively start at interior inclusions. Considering inclusions as cracks, the maximum stress intensity factor of a load cycle being below the effective threshold stress intensity factor determines the fatigue limit.

Solidification and recovery of Cr from hazardous Cr-bearing steel slag: Selective solidification, super-gravity separation and crystal characterization

Massive hazardous Cr-bearing steel slag is produced from the electric furnace smelting process of stainless steel, while the soluble poisonous hexavalent chromium (Cr(VI)) seriously limits the sustainable utilization of the slag. In this study, a novel method of selective solidification and super-gravity separation was proposed to recover Cr resources from Cr-bearing steel slag safely and efficiently. Firstly, Cr elements were selectively solidified into Cr-spinel in Cr-bearing steel slag with wt.%(MgO) = 6.00, and the high-purity Cr-spinel crystals ((Mg0.43Fe0.28Mn0.29)(Cr1.67Al0.33)O4) were effectively recovered from the molten slag via super-gravity separation with a significant Cr2O3 content of 58.08 wt% and a high Cr recovery rate of 88.58 %. On this basis, the chemical formulas and crystal structures of various high-purity Cr-spinel crystals were characterized and the solidification mechanism of Cr in Cr-spinel was determined, to verify that Cr3+ was accordingly substituted by Al3+ when Fe2+ and Mn2+ were substituted by Mg2+, and Cr elements were efficiently solidified and recovered into the Cr-spinel in stable trivalent chromium (Cr(III)) based on the XPS results. Thus the effective leaching amount of Cr in Cr-spinel was as low as 0.011 mg/L, which provided a basis for sustainable utilization of Cr-bearing steel slag.

Tribological and Mechanical Properties of the Nanostructured Superlattice Coatings with Respect to Surface Texture

Ceramic Nanostructured Superlattice Coatings (NSC) have broad applicability to improve the parts’ and assemblies’ tribological and mechanical properties for the needs of the automotive and aerospace industries. Improving the material properties using nanocoatings for such a widely used material as, for example, bearing steel 100Cr6 makes it possible to improve the service life of machine parts. In this paper, the correlation dependence between tribological and mechanical properties of the NSC and its surface texture are considered to determine how much surface texture will affect the tribological performance of the coated workpieces, as well as the measuring and evaluation procedure of the nanocoatings, are presented. Three different NSC described by a general empirical formula {TiMe1Me2-CN/TiAlSi-N}n and based on the modified carbonitride/nitride non-stoichiometric chemical composition were created, and their tribological and mechanical properties measured and analyzed in the context with surface texture. NSC deposited by the advanced PVD (Physical vapor deposition) technique demonstrated significantly higher wear resistance (up to 28 times), reasonably lower friction coefficient (CoF) (up to 4 times), and significantly higher hardness of the coated workpieces (up to 7 times) versus substrate material. A strong correlation between the steady-state dry sliding friction, CoF, and the amplitude and functional surface texture parameters of tribo-track were observed. The first results of the initiated research regarding the correlation analysis of the tribological and mechanical properties, on the one hand, and surface texture, on the other hand, of the NSC are reported here.

Verhalten von Kurvenrollen unter verschiedenen Querschlupfbedingungen

With the aid of the universal orthogonal two-disk tribometer „MopeD Qs2STg500“, a new application-oriented method is developed for testing stud type track roller materials and lubricants under various running conditions. The tests are carried out under circulating oil lubrication. This laboratory test method is used to map cam roller gears from a wide range of industrial applications, such as gear changes on lathes in series production or the implementation of cyclic motion profiles on automatic machines. The wear tests are carried out on two different axial cam materials with cam rollers made of the standard rolling bearing steel 100Cr6.

Experimental Investigation on the Effect of Deep Cryogenic Treatment on 100Cr6 Bearing Steel

Cryogenic treatment is the process of cooling a material to extremely low temperatures to generate enhanced mechanical and physical properties. The present investigation examines the effect of deep cryogenic treatment on the enhancement of mechanical properties, such as wear resistance, corrosion resistance, tensile strength and impact strength of the plunger material 100Cr6 bearing steel. The improvement in the wear resistance, corrosion resistance, tensile strength and impact strength of the deep cryogenically treated samples over the conventionally heat-treated ones, is 50%, 26%, 13% and 27% respectively. This study suggests that the formation of very small carbides dispersed in the tempered martensite structure, can be the main reason for the enhancement of certain mechanical properties, along with the retained austenite transformations.

Hole tolerance properties of aluminium and bearing steel in CNC plasma cutting process

In this study, hole tolerances were investigated by creating holes on 6061-T6 Aluminium and 100Cr6 Bearing Steel in the CNC plasma machine. Holes with diameters of 4, 6.5 and 9 mm were cut circularly in the plates of 3, 6 and 10 mm thickness. The experiments were carried out at three different cutting speeds. Delamination factor, circularity error and taper values were measured. The amounts of burrs formed as a result of circular cut were investigated. For the same plate thickness and hole diameter, as the cutting speed increased, the delamination factor did not change much, but the circularity error and taper values increased. It was observed that the difference between the inlet and outlet diameters decreased as the plate thickness increased. This reduced the circularity error and taper. As the cutting speed increased, the delamination factor, circularity error and taper values increased. As a result of the regression and variance analysis, it was seen that the most important effect on the hole quality was the cutting speed. It has also been observed that the hole quality of 100Cr6 Bearing Steel was better than 6061-T6 Aluminium alloy.

Analysis of Surface State after Turning of High Tempered Bearing Steel.

This paper investigates surface state after turning of the high tempered bearing steel 100Cr6 with a hardness of 40 HRC. White layer (WL) thickness and its microhardness, as well as surface roughness, are investigated as a function of tool flank wear VB as well as cutting speed vc. The mechanical and thermal load of the machined surface were analysed in order to provide a deeper insight into their superimposing contribution. Cutting energy expressed in terms of cutting force was analyses as that consumed for chip formation Fγ and consumed in the flank wear land Fα. It was found that the mechanical energy expressed in terms of the shear components of the Fα grows with VB, converts to the heat and strongly affects the thickness of the re-hardened layer. Furthermore, the superimposing contribution of the heat generation and its duration in the VB region should also be taken into account. It was also found that the influence of VB predominates over the variable cutting speed.

Characterization of the Interface between Aluminum and Iron in Co-Extruded Semi-Finished Products.

Within the framework of the Collaborative Research Center 1153, we investigated novel process chains for the production of bulk components with different metals as joining partners. In the present study, the co-extrusion of coaxially reinforced hollow profiles was employed to manufacture semi-finished products for a subsequent die-forging process, which was then used for the manufacture of hybrid bearing bushings. The hybrid hollow profiles, made of the aluminum alloy EN AW-6082 paired with either the case-hardening steel 20MnCr5, the stainless steel X5CrNi18-10, or the rolling bearing steel 100Cr6, were produced by Lateral Angular Co-Extrusion. Push-out tests on hybrid hollow sections over the entire sample cross-section showed shear strengths of 44 MPa ± 8 MPa (100Cr6) up to 63 MPa ± 5 MPa (X5CrNi18-10). In particular, the influence of force and form closure on the joint zone could be determined using specimen segments tested in shear compression. Locally, shear strengths of up to 131 MPa (X5CrNi18-10) were demonstrated in the shear compression test. From these samples, lamellae for microstructural analysis were prepared with a Focused Ion Beam. Detailed analyses showed that for all material combinations, a material bond in the form of an ultra-thin intermetallic phase seam with a thickness of up to 50 nm could be established.