Bearing Steel 100Cr6 Research Articles

Laser Metal Deposition welding with high carbon steel wire material 100Cr6

The bearing steel 100Cr6 is of great interest for cladding applications that are subject to tribological stresses, since it has high hardness of up to 62 HRC. However, the material is considered not weldable due to its high carbon content. In this study, a process for laser metal deposition welding with the wire material 100Cr6 is developed. For the welding experiments a coaxial deposition welding head is used and the cladding is applied on flat steel of the material S235. Suitable parameter sets for the production of single-layer claddings are determined. The transferability of the results to multilayer claddings is examined. The claddings are analyzed with respect to hardness, microstructure, dilution and the occurrence of welding defects such as pores and cracks. The investigations indicate that an adjustment of the welding parameters is necessary for the deposition of the second layer of the cladding

Cementite decomposition in 100Cr6 bearing steel during high-pressure torsion: Influence of precipitate composition, size, morphology and matrix hardness

Premature failure of rail and bearing steels by White-Etching-Cracks leads to severe economic losses. This failure mechanism is associated with microstructure decomposition via local severe plastic deformation. The decomposition of cementite plays a key role. Due to the high hardness of this phase, it is the most difficult obstacle to overcome in the decaying microstructure. Understanding the mechanisms of carbide decomposition is essential for designing damage-resistant steels for industrial applications.We investigate cementite decomposition in the bearing steel 100Cr6 (AISI 52100) upon exposure to high-pressure torsion (maximum shear strain, Ƴmax = 50.2). Following-up on our earlier work on cementite decomposition in hardened 100Cr6 steel (Qin et al., Act. Mater. 2020 [1]), we now apply a modified heat treatment to generate a soft-annealed microstructure where spherical and lamellar cementite precipitates are embedded in a ferritic matrix. These two precipitate types differ in morphology (spherical vs. lamellar), size (spherical: 100–1000 nm diameter, lamellar: 40–100 nm thickness) and composition (Cr and Mn partitioning). We unravel the correlation between cementite type and its resistance to decomposition using multi-scale chemical and structural characterization techniques.Upon high-pressure torsion, the spherical cementite precipitates did not decompose, but the larger spherical precipitates (≥ 1 μm) deformed. In contrast, the lamellar cementite precipitates underwent thinning followed by decomposition and dissolution. Moreover, the decomposition behavior of cementite precipitates is affected by the type of matrix microstructure. We conclude that the cementite size and morphology, as well as the matrix mechanical properties are the predominating factors influencing the decomposition behavior of cementite. The compositional effects of Cr and Mn on cementite stability calculated by complementary density functional theory (DFT) calculations are minor in the current scenario.

Micromechanical and Tribological Properties of Nanostructured Carbonitride Coatings Deposited by PVD Technique

Nanostructured smart coatings (NSC) based on the TiAlSi-CN composite structure elements were deposited using reactive high-power physical vapor deposition (PVD) technique. The advanced modular deposition system included up to 8 high-power magnetron sputtering devices (MSD) allowing operate them simultaneously and exceed power density of 120 W/cm2 within each device erosion zone. The novel designed NSC on bearing steel 100Cr6 substrates demonstrated enhanced mechanical and tribological properties comparably with bearing steel ones required for multifunctional high-tech applications. The deposited NSC containing TiAlSi-CN nanoparticles strengthened by elemental additives Cr and Nb exhibited microhardness as high as 2500 HV values in comparison with 750 HV of 100Cr6 steel substrates. Load-displacement curves obey Meyer’s power-law surprisingly well because power-trendline fitted ones by R-squared value of 0.9999 for all the film-samples. Tribological properties were measured under dry friction conditions between the bearing steel ball of Ø 6 mm and the film-samples’ flat surface. Coefficient of friction (CoF) ranges between 0.22-0.56 depending on a sample and load. Tribotracks worn under the friction indenter were too shallow to evaluate them by Mitutoyo profilometer SJ-500. Therefore, the wear rate was estimated as ball wear of the friction indenter.

Study of the process of rolling steel balls in skew rolling mill – metallographic analysis

This paper presents the results of metallographic research studies carried out for stock materials as well as the samples collected from the balls formed in the rolling process in a skew rolling mill. The stock material was bearing steel 100Cr6 and the steel from rail scrap. The rolling process was carried out in parallel for the two assumptions: the conventional method (hereinafter referred to as conventional rolling) and the modified method (hereinafter referred to as modified rolling). After the rolling process, three cooling media were used: air, water and oil. The pictures below, which depict microstructures, were taken using the bright-field and the dark-field microscopy technique, the samples were etched with a 4% solution of picral.

High Temperature Dry Tribological Behavior of Nb-Microalloyed Bearing Steel 100Cr6.

100Cr6 steel is one of the most widely used bearing steels and a representative of first-generation bearing steel. Many engineering applications require rolling bearings to run at a high temperature. Therefore, it is necessary to improve the high temperature properties of 100Cr6 steel. In this paper, the effect of Nb on high temperature dry tribological behavior, including worn surface and friction coefficient, was analyzed by a wear test when Nb content was 0.018% and 0.040%. The results show that the microstructure is refined gradually, the hardness is improved, and wear volume decreases by 31.8% at most with the increase of Nb content. At 50 °C, the friction coefficient of 100Cr6 steel can be reduced by adding a small amount of Nb, but this effect will be weakened if the content of Nb is too high. In addition, excess Nb increases the hard precipitation of NbC, which aggravates the abrasive wear and leads to the increase in the depth of the worn surface. At 125 °C, the effect of Nb on tribological properties is weaker. With the increase of temperature, the steel substrate softens, and the oxide particles increase, which aggravates the abrasive wear and oxidation wear and makes the wear volume increase significantly.

Impact of steel type, composition and heat treatment parameters on effectiveness of deep cryogenic treatment

In recent years, promising technique of deep cryogenic treatment (DCT) is taking a new step in improving properties of various materials, especially steels. This study is focusing on influence of selected heat treatment process involving deep cryogenic treatment on the microstructure and microstructural evolution of four different steel grades (bearing steel 100Cr6, cold work tool steel X210Cr12, hot work tool steel X38CrMoV5-3 and stainless steel X17CrNi16-2). The study was performed for different heat treatment conditions, focused on effectiveness of DCT when using different austenitizing and tempering temperatures. The evolution of the microstructure was investigated in a sequential manner with various analytical techniques. The study indicates that the microstructure and microstructural evolution and changes are strongly related to the chemical composition of steel and the predefined matrix microstructure. DCT increases precipitation of carbides and induce their more homogenous distribution. The magnitude of increased carbide precipitation after DCT is correlated with the higher carbon content, whereas the content of other alloying elements does not scale with the precipitation behavior. The obtained results indicate that incorporation of DCT with heat treatment with higher austenitizing and lower tempering temperature is the most suitable for improving steels’ properties with DCT, due to the stronger impact of DCT on the carbide precipitation and matrix modification.

Effect of inclusions on the fatigue strength of a bearing steel

Here are presented results of experimental investigation about effect of inclusions on the fatigue strength of a bearing steel 100Cr6. Fatigue tests were carried out at sinusoidal cyclic tension-compression loading, f = 190 Hz, R = −1, room temperature, in the region ranged from N ≈ 3.5 × 105 to N ≈ 1.0 × 108 cycles of loading. Initiation of the fatigue cracks was observed in the bulk of the tested specimens and the so-called “fish eyes” were observed, mainly on the TiN inclusions (66 % Ti, 19 % N, 9 % Cr, remainder Fe, V, Zr). The TiN inclusions are hard, with sharp edges causing a significant stress concentration in a small localized area, resulting in an initiation of a fatigue crack. On the other hand, in standard for the chemical composition of this steel, the content of Ti was not prescribed.

Influence of Cutting Speed in Turning and Force in Subsequent Diamond Smoothing on Magnetic Properties of Steel 100Cr6

Magnetic properties are known to be crucial in the application of electrical steel and they are therefore covered by manifold studies. Other ferromagnetic materials are out of scope in this respect, even if the importance of magnetism of conventional steel is evident. Additionally, there is a contradiction regarding the major influence on magnetic properties. Machining, transport, and storage are possible influencing variables. In the experimental investigations, specimens consisting of the bearing steel 100Cr6 are machined by turning and partly by subsequent diamond smoothing. While machining using several cutting speeds and smoothing forces, the thermoelectrical voltage, current, and the components of the resultant force are recorded. The results show how the near-surface plastic deformations evolve throughout the machining process. Additionally, it was found that the magnetic properties and other properties of the surface layer are influenced in different ways depending on turning and diamond smoothing parameters. Correlations between in situ and ex situ measured values are shown. This study aims to solve the aforementioned question by quantification of machining impacts of cutting speed in turning and force in diamond smoothing and its dependence on transport and storage.

Conformable metal oxide platelets – A smart surface armor for green tribology

The reduction of friction and wear is a crucial performance criterion for most technical processes. This is particularly true for the ubiquitous case of oil lubricated machinery made from steel components. Here we introduce a facile laser treatment that significantly enhances the tribological performance of bearing steel 100Cr6, a material widely used for the manufacture of ball and roller bearings. By applying repeated nanosecond-pulses of focussed laser-beam irradiation under ambient air, a surface-protective tribo-layer is generated by a method that exploits self-organization for the formation of conformable metal oxide platelets consisting of vertically aligned transition metal oxides nanorods on the steel substrate. These submicron-sized metal oxide platelets protect the surfaces similar to scale armor and the tribological performance of the bearing steel 100Cr6 was significantly enhanced. Based on laboratory tests using a rotational pin-on-disk tribometer under oil lubricated conditions, close to zero wear with simultaneous reduction of friction by 54% was achieved. Even under the harsh conditions in the pin-on-disk tribometer these metal oxide platelets turn out to be remarkably robust against detachment and crumbling for lasting millions of cycles at a slip rate of 100%. The origin of this resilience is based on a special substructure of the platelets that, counter-intuitively for ceramic material, enables shape adaptations to surface deformations emergent upon high mechanical stress.

Effects of Al Content on the Corrosion Behaviors of Low Cr Bearing Steels in NaCl Solutions

Effects of Al Content on the Corrosion Behaviors of Low Cr Bearing Steels in NaCl Solutions

Spheroidization of 100Cr6 Bearing Steel by Warm Forging

Warm forging of a (1%C–1.5%Cr) bearing steel at 760 and 800 °C could enable the achievement of a fully spheroidized microstructure comparable to that of the steel spheroidized by long-duration annealing treatment. The deformation-induced spheroidization gave higher hardness, strength, and toughness than the annealed steel. The deformation-induced grain structure and the finer dispersion of the residual carbides at the warm forging temperature promoted divorced eutectoid transformation when the steel was cooled below A1 temperature. A still higher temperature warm forging at 820 °C gave a partially spheroidized microstructure, with a significant fraction of pearlite colonies, resulting in inferior mechanical properties. The lower equilibrium carbide at higher warm forging temperature gave large islands of austenite devoid of carbides, which on cooling below A1 transformed to pearlite. The microstructure evolution and mechanical properties were examined at various stages of processing.

Structural and mechanical properties of W-C: H coatings prepared by HiTUS

The structure and mechanical properties of hydrogenated tungsten-carbon (W-C: H) coatings have been studied as a function of the composition and structure. These coatings were prepared by the High Target Utilization Sputtering (HiTUS), the first time used for this type of coatings. W-C: H coatings were deposited from tungsten–carbide target in argon, argon–acetylene (C2H2), and argon–methane (CH4) atmosphere on bearing steel 100Cr6 substrate, Al substrate, Si wafer a, and WC-Co substrate. W-C: H coatings obtained at different acetylene and methane flow were characterized by Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS), X-ray diffraction, Transmission electron microscopy (TEM), and nanoindentation. Mechanical properties of these coatings are controlled within a range through a change in mutual concentration of crystalline phase and amorphous hydrogenated carbon matrix. The higher hardness (Hit = 29.5 ± 4.5 GPa) was measured for coating with 3 sccm methane addition. W-C: H coatings with more than 4 sccm of C2H2 and CH4 addition had fully amorphous structure and worse off mechanical properties.

Corrosion behavior of Cr-bearing steels in CO2-O2-H2O multi-thermal-fluid environment

Multi-thermal fluid is used to enhance heavy oil recovery, but it also causes severe corrosion failure of metallic tubing and its mechanism is still open to debate. In the present work, the corrosion behavior of commercial steels with different Cr content (3 wt%, 9 wt%, and 25 wt%) in simulated CO2-O2-H2O multi-thermal fluid environments were studied by immersion corrosion test and microstructural characterization. The results exhibit that the Cr content of steel determines the type of corrosion products. The less protective corrosion scale is mainly composed of FeCO3, (Fe, Cr)3O4, and Fe2O3, which is formed on the surface of 3Cr and 9Cr steels. The protective corrosion scale is mainly Cr2O3, which is formed on the surface of 25Cr steel. Only when the Cr content in steel is sufficient (i.e. 25 wt%) to repair the serious depletion of Cr in the metal near the scale/metal interface in time, can protection of the corrosion scale be sustained, to improve its ability to resist the corrosion of multi-thermal fluids.

Mechanism of cementite decomposition in 100Cr6 bearing steels during high pressure torsion

Severe plastic deformation leads to cementite decomposition in pearlitic and martensitic alloys, resulting in high-strength nanocrystalline ferrite. This effect can be employed to strengthen pearlitic wires but it can also be associated with material failure by white etching cracks (WECs) that are primarily known to concern bearings or rails. We investigate the decomposition of spheroidal cementite in the martensitic bearing steel 100Cr6 with 62 Rockwell hardness during high pressure torsion at 9.5 GPa applied pressure. The hard martensitic matrix and the even harder spheroidal cementite precipitates behave plastically very differently. The enforced macroscopic plastic deformation is almost entirely carried by the matrix. Plastic material flow of the matrix around the spheroidal cementite leads to wear of the spheroidal cementite as indicated by continuously increasing levels of chromium in the matrix. Plastic deformation of spheroidal cementite via dislocation gliding supposedly accelerates this process as slip steps generated thereby are preferential sites of wear at the matrix/cementite interface. Larger spheroidal cementite precipitates are more prone to plastic deformation and to decomposition than smaller ones. The mechanism likely holds true in general for multiphase materials with large strain difference between phases subjected to high pressure torsion. Although the formation of WECs in 100Cr6 bearings might be slowed down by reducing the size of the spheroidal cementite precipitates, it is unlikely that this could entirely prevent this failure mechanism.

Characterization of Molybdenum Based Coatings on 100Cr6 Bearing Steel Surfaces

Characterization of Molybdenum Based Coatings on 100Cr6 Bearing Steel Surfaces

ToF-SIMS analysis of boundary layers formed under zinc-free antiwear

PurposeThe structure and chemical composition of boundary layers built under tribological stress affect the friction and wear of solid-state surfaces in a major way. Therefore, information about the chemical composition of the outermost surface and boundary layer are of great importance. Preliminary time of flight secondary ion mass spectrometry (ToF-SIMS) investigations have shown that metal surfaces that have been immersed at high temperatures in phosphonium phosphate-containing oils contain at least some characteristic signals for phosphate containing anti-wear layers. The purpose of this work is to investigate the influence of additive concentration and oil temperature on the formation of phosphate containing layers.Design/methodology/approachTo investigate the formation of phosphate containing layers as a function of temperature, samples of rolling bearing steel 100Cr6 were first heated in a furnace to selected temperatures of 200, 300, 400 and 500 °C, respectively. Then, they were immersed in a model fluid containing ionic liquids as additive in PAO-2 and analysed by ToF-SIMS.Findings100Cr6 surfaces immersed in trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate additive oil show characteristic signals of phosphate-like layers at temperatures of 400-500 °C. In addition, characteristic surface signals show a decrease in these ionic liquids at these temperatures.Originality/valueIonic liquids could be an alternative to zinc dialkyldithiophosphates as an oil additive. Targeted investigations under friction load could provide information on whether wear-reducing layers are formed.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0436

Investigation of tribological properties of CarbonX coating deposited on 100Cr6 steel

Abstract The article deals with a reduction of friction coefficient of bearing steel 100Cr6. Reduction of friction was achieved by means of a CarbonX DLC coating. The coating exhibited excellent friction and mechanical properties. This coating was applied to samples made of 100Cr6 bearing steel. The friction results of the CarbonX coating were compared to the friction results of the 100Cr6 bearing steel. Reducing the friction of 100Cr6 bearing steel resulted in reduced wear and increase lifetime. The friction process of the samples will take place in an environment without lubrication. The aim of the article is to verify the behaviour of the DLC coating without the presence of lubricant in the friction node. The achieved results are to be interpreted in the conclusion of article.

Carburization induced extra-long rolling contact fatigue life of high carbon bearing steel

For the first time, vacuum carburization surface treatment was applied to high carbon bearing steel 100Cr6. The rolling contact fatigue (RCF) life and the wear behavior of 100Cr6 with and without carburization were compared and the microstructure was characterized. The carburization results in 30 vol% cementite and ~20 vol% retained austenite in the surface layer, significantly higher than those processed by the conventional heat treatment. RCF life (L10) is significantly enhanced by more than 10 times from 1 × 107 cycles to ≥1 × 108 cycles by carburization. This enhancement is attributed to plate/rod cementite and retained austenite.

Nondestructive Detection and Analysis of Skidding Damage for Bearing Steel 100Cr6 Using Improved Magnetic Barkhausen Noise Technique

Skidding damage, which extensively appears in the bearings at a high rotation speed, often shortens the lifetime of bearings and even induces the total failure of the bearings. This paper proposes a novel nondestructive measurement system for evaluating the degree of skidding damage by using the improved magnetic Barkhausen noise (MBN) technique. A ring-type probe with a bias current is designed to capture the weak MBN signal generated from the narrow section in the ferromagnetic material. It can increase the detection resolution of skidding damage compared to the commonly employed cylindrical probe. The excitation frequency of the electromagnetic field is optimized to enhance the strength of the MBN signal, and the background noise is suppressed by a bandpass filter. One sample with different degrees of skidding damage is prepared and detected. Experiments demonstrate that the skidding damage can suppress the generation of the MBN signal in the sample, and the peak amplitude of the MBN signal envelope gradually declines with the increase in the degree of skidding damage. These indicate that the skidding damage on the bearing steel can be evaluated by the proposed measurement system.

The Effect of Machined Surface Conditioning on the Coating Interface of High Velocity Oxygen Fuel (HVOF) Sprayed Coating

Roughening the substrate surface is essential for thermal sprayed coatings. In this regard, sandblasting has established itself as an easy to use surface conditioning procedure. The quality of the obtained roughness depends on the conditions of the sandblasting material, adjusted parameters, and the kind of the process execution (manual or mechanical). These preconditions limit the reproducibility of the roughness obtained. Sandblasting causes residual compressive stress and may also lead to the inclusion of sand particles and notches in the roughened surface, which affects the interfacial properties of the coating, as well as the flexural strength of the coated parts. The hardness of the roughened surface plays, thereby, an important role. However, in order to reliably avoid these effects, microfinishing can be used as an alternative to generate a homogenous roughened substrate surface, control the induced residual stresses, and increase the reproducibility. In addition, the roughened surface pattern can be produced during the chip forming process of the to-be-coated parts. The utilization of the appropriate combination of machining processes and parameters should lead to the required surface pattern and thus to an enhanced coating adhesion and flexural strength of the coated part. The induced residual stresses and the quality of the obtained surface roughness have a significant influence on the coating adhesion and the lifespan of the coated parts. This paper aims to analyze, as a first step, the effect of the turning and microfinishing on the surface conditioning of the bearing steel 100Cr6 (AISI 52100). The investigation concludes by comparing the microfinished with the sandblasted surfaces with regard to the interface to and the adhesion of the WC–Co high velocity oxygen fuel (HVOF) sprayed coatings on them. Surface conditioning plays a decisive role by the induced residual stresses and the elimination of adhesion defects.