Steel Pair Research Articles

Tribological properties of diamond-like carbon films lubricated with water-emulsified engine oil

In this work, the tribological properties of two diamond-like carbon (DLC) films were investigated at different temperatures using water-engine oil emulsions as lubricants, considering emerging fuel systems such as hydrogen and ammonia. The results revealed that the friction coefficient of a-C film raised with the increasing water content at 80 °C. The friction coefficient of a-C:H film initially raised and then decreased with varying water fractions at different temperatures. Elevated temperature exacerbated the wear of both DLC films at high water contents. The most significant wear was observed for a-C film at 80 °C and a-C:H film at 50 °C. The a-C:H film exhibited more sensitive wear characteristics to water content than the a-C film. Surface analysis indicated that water-engine oil emulsions prevented the formation of phosphate tribo-film on steel friction pair for two DLC films but promoted the tribo-oxidation of steel pair sliding contact with a-C film, especially at higher temperatures. Distinct reactivities of two DLC films towards water molecules could affect the adsorption of lubricants on DLC surfaces, leading to their different friction and wear behavior. It suggests that the water-caused emulsification of lubricating oil will be a pivotal consideration in tribological applications of DLC films in future internal combustion engines.

Dissimilar impact spot welding of high-thickness aluminum-steel sheets using vaporizing foil actuators

The automotive industry’s shift towards multi-material structures necessitates efficient joining of aluminum and steel, yet techniques for high-thickness (>2 mm) dissimilar AA6XXX-HSLA steel pairs, remain underexplored. This study explores vaporizing foil actuator welding for spot welding 2.5 mm AA6111-HSLA 340 steel pairs, demonstrating successful joint formation via lap-shear testing and microscopy. Post-weld heat treatment influences joint strength and fracture behavior, with intermetallic compound (IMC) formation at the weld interface affecting mechanical properties. IMC cracking is observed in heat-treated samples. Fracture analysis reveals material transfer and secondary brazing action outside the weld zone. VFAW lap-shear failure loads outperform other joining techniques.

Numerical Analysis on Frictional Heat Effect in Polyether-Ether-Ketone (PEEK)/Steel Pair by using OpenFOAM Model

The PEEK material has been applied to a sliding bearing system in a power plant system because of its high mechanical durability. In the solid friction of the PEEK materials, the frictional heat becomes the important factor because the temperature increase due to the frictional heat causes the rapid increase of the frictional coefficient of the specimen. To maintain the low frictional coefficient of the PEEK materials, an effective cooling method for the PEEK materials needs to be developed. In this study, the passive cooling method, which attaches the heat sink to the PEEK materials, was suggested. For evaluating the suggested cooling method of the PEEK materials, the calculation model adopting OpenFOAM, which is open-source software, has been developed. Adopting some functions and libraries of OpenFOAM, the frictional heat, heat resistance, and heat transfer coefficient on the heat sink were modelled. The sliding bearing experiment was conducted and time variation of the temperature and friction coefficient in the ring specimen were measured. The temperature variation in the ring specimen was compared with the calculation result. From the numerical calculation results, the developed calculation model could simulate the temperature-time variation of the ring obtained in the experiment, when the variation of the frictional coefficient, heat resistance, and heat transfer coefficient was modelled appropriately. Based on the friction and wear test results, by applying a heat dissipation mechanism to the ring test piece, the calorific value of the PEEK material can be reduced, and it is stable. It was suggested that the friction was maintained.

Express Method for Assessing Performance of Lubricant Compositions Containing Nano-Additives Used for Wheel-Rail Pairs.

An express method for assessing the effectiveness of lubricating compositions with nano-additives of various chemical compositions is proposed, and a joint analysis of experimental data on the changes in the value of wear and the level of damage to the surface layers of metallic friction pairs was performed. The variation in the current relative hardness of the sample's surface, the variation in the current relative material damage level, the current value of wear, and the current level of the coefficient of friction were chosen as the key parameters to conduct a performance assessment. The level of material damage in the contact zone was determined using the parameters of the statistical law of hardness value scattering. Based on an analysis of data in the literature, it was observed that the structural changes occurring in metallic materials during long-term, cyclic, static, and frictional loading are correlated with changes in the statistical characteristics of the hardness scattering results. An experimental substantiation of the proposed method was carried out for steel-sliding friction pairs using lubricating compositions based on Greaseline Lithium BIO Rail 000 oil manufactured by AIMOL with nano-additives of copper, magnesium and aluminum alloys, graphite, and two grades of medium-carbon steel. According to the system of indicators presented in this research, the greatest efficiency (in terms of increasing the wear resistance of friction steel pairs) was achieved with lubricating compositions including nano-powder additives made of steel, which have lower hardness. For the friction experiments, where the determining factor was abrasive wear, such lubricants ensured minimal damage and wear to the friction surface, while the value of the friction coefficient was maintained at a level that is optimal for wheel-rail friction pairs.

Wear mechanism and evolution of tribofilm of ceramic on steel pairs under ester oil lubrication in wide temperature range

The ceramic-steel-pentaerythritol ester system has a broad application prospect under high temperature conditions, which are respectively in the fields of aviation, aerospace and advanced equipment manufacturing. However, a comprehensive understanding of the friction and wear mechanisms of this system across a broad temperature range remains elusive. The tribological properties of the system at 25–475 °C were studied. With the increase of temperature, the evolution of the tribofilm follows the sequence: discontinuous tribofilm → uniform tribofilm → tribofilm removal. At 200–300 °C, an approximately 100 nm thick amorphous PxOy compound tribofilm is formed, and its nanohardness and modulus are reduced by 81.33 % and 54.02 %, respectively, compared with base steel. The tribofilm effectively reduces shear resistance by blocking friction pair contact. When the temperature exceeds 300 °C, it will lead to high-temperature coking, which adversely affects the lubrication performance. It is worth noting that the system can endure short-term service at a maximum temperature of 475 °C. Therefore, this research can help achieve continuous, stable operation of high-temperature resistant systems, as well as short-term use under extreme conditions encountered by complex equipment.

Hexagonal boron nitride nanosheets eco-friendly dispersed in pure water for lubrication in fretting contacts between steel pairs

The lubricating effect of h-BN nanosheets, dispersed in pure water without the use of any chemicals, was investigated under fretting contacts. The resistance against oxidation of sliding pairs was also considered using AISI 52100 and AISI 304 steel pairs separately, given that oxidation is inevitable on steel surfaces. In the partial slip regime, effects of the type of lubricant and oxidation on wear and friction were insignificant. In the mixed slip regime, the mending effect of h-BN counteracted the oxidation of sliding surfaces, resulting in mild wear. In the gross slip regime, the mending effect collapsed due to oxide debris, resulting in severe wear. Moreover, the results showed that the presence of h-BN nanosheets influenced the transition of fretting regimes. These findings suggest that aqueous-dispersed h-BN nanosheets can be an effective eco-friendly lubricant additive, particularly when fretting conditions enable a stable mending effect and sliding surfaces exhibit high corrosion resistance.

Effect of Molybdenum Disulfide Dispersed Nanolubricants on the Tribological Properties of Mating Stainless Steel Pair

Effect of Molybdenum Disulfide Dispersed Nanolubricants on the Tribological Properties of Mating Stainless Steel Pair

Effect of Graphite Filling Pore Structure Size on the Tribology Behaviors of Tin Bronze/45 Steel Pairs With Grease Under Low-Speed and Heavy Load Conditions

Effect of Graphite Filling Pore Structure Size on the Tribology Behaviors of Tin Bronze/45 Steel Pairs With Grease Under Low-Speed and Heavy Load Conditions

Ionic liquid lubricants of PLA. New self-lubricating (PLA+ionic liquid) materials

Friction coefficients and wear rates of polylactic acid (PLA)-stainless steel pair have been determined under two different contact configurations using four aprotic imidazolium and a bio-based protic ammonium ionic liquid (IL) lubricants. Under rotational pin-on-disk, all ILs reduce friction coefficient in more than one order of magnitude and prevent wear. Under linear reciprocating sliding, the best performance is found for the halogen-free protic ammonium IL, with the highest viscosity and lower contact angle values. New (PLA+IL) materials have been obtained and excellent self-lubricating performance has been found for those with a porous surface. Results are discussed upon the basis of rheology, contact angles, surface topography and electron microscopy (SEM/EDX) studies.

Galling of stainless steels as a function of test conditions in an ASTM G196-type test setup – The role of temperature, rotational velocity, interrupted rotation and rotational distance

Austenitic stainless steels have attractive properties for use in corrosive environments, but their use in components where motion under load is experienced (such as valves) is limited by their poor galling behaviour. Whilst stainless steels with improved performance have been developed over many years, the basic understanding of the key parameters in galling of standard stainless steels is not well understood. In this work, the galling behaviour of a dissimilar austenitic stainless steel pair is explored via testing in an instrumented ASTM G196-type test. Key variables examined are environmental temperature (room temperature and 100 °C), rotational speed (2.1 rpm and 5.5 rpm), and the sliding distance (from a quarter of a turn up to five turns). Galling was observed to become more severe with increased temperature, but was not significantly affected by either sliding speed (in the range examined) or interruptions during the rotation. The measurement of friction coefficient along with surface observations revealed that galling does not take place within the initial period of sliding; however, damage is being accrued by the sample surfaces which then results in subsequent observable galling as the sliding distance is increased. The importance of measuring torque during galling tests is illustrated, and the findings provide useful information with regard to those test variables that require critical control (and which do not) during conduct of a galling test programme.

Study on the Tribological Properties of Polymer Interface and the Mapping Mechanism of Friction Noise in a Wide Temperature Range

In order to study the tribological properties and frictional noise mapping mechanism of polymer interface at a wide temperature range, tribological and frictional noise acquisition tests were carried out on a Ball-on-Three-Plates Tribology Accessory. The friction coefficient and noise signal data sets were collected for 15 minutes from the friction surfaces of polytetrafluoroethylene and 0Cr18Ni9 austenitic steel pairs at six temperatures and three constant loading-speed contact points in a wide temperature range of -150°C-25°C. The wear rate of the polymer was measured and the wear state of the polymer interface was studied by field emission environmental scanning electron microscopy (SEM). Based on the analysis of the time-frequency domain characteristics of friction noise and the qualitative mapping relationship between the wide-temperature domain tribological properties and friction noise, the theoretical and experimental basis is provided for establishing online early warning monitoring of the tribological performance of polymer-metal friction pairs based on the time-frequency domain characteristics of friction noise.

Effect of heat treatment on notch toughness of powdered tool steels M390 and M398

This paper deals with the possibilities of heat treatment of a pair of tool steels, produced by the powder metallurgy. The investigated steels named M390 and M398 belong to the group of high-alloy chromium steels used in the plastics industry in the production of screws for injection moulding machine unit. The steels were heat treated using quenching or quenching with deep freezing to achieve a homogeneous martensitic structure. Subsequently, the pair of steels was tempered twice in the temperature range from 200°C to 600°C. The given samples were experimentally tested for hardness and notch toughness using a Charpy hammer. The results compared the values of hardness and notch toughness depending on the tempering temperature. Selected fractures were observed using SEM microscopy.

Effect of the Addition of Fullerene Soot to Litol-24 Grease on the Basic Laws of Sliding Friction in the R6M5 Steel–45 Steel Pair

Effect of the Addition of Fullerene Soot to Litol-24 Grease on the Basic Laws of Sliding Friction in the R6M5 Steel–45 Steel Pair

Feasibility of Production of Multimaterial Metal Objects by Laser-Directed Energy Deposition

The article focuses on the possibility of manufacturing bimetallic products for specific industrial applications using laser-directed energy deposition (LDED) additive technology to replace the traditional brazing process. Preferential process regimes were determined by parametric analysis for the nickel-alloy–steel and molybdenum–steel pairs. Comparative studies of the microstructure and hardness of the deposited layers and the transition layer at the boundary of the alloyed materials have been carried out. It is shown that LDED provides better transition layer and operational properties of the final part since the low-melting copper layer is no longer needed. A combined technological process has been developed, which consists in combining the traditional method of manufacturing a workpiece through the casting and deposition of a molybdenum layer by LDED.

Optimization of Welding Parameters of AISI 431 and AISI 1020 Joints Joined by Friction Welding Using Taguchi Method

Martensitic stainless steel AISI 431 and low carbon steel AISI 1020 are materials used together in many different industries. However, important problems are encountered when welding (fusion welding) these materials to each other. For this reason, friction welding process (Solid-state welding) is used to join these dissimilar metals. There are very few studies on joining these materials with friction welding. Therefore, the optimization of the welding parameters used in joining these dissimilar steel pairs with friction welding is of great important. In addition, the effects of the factors dependent on friction welding parameters need to be well understood. In this study, AISI 431 and AISI 1020 steel bars were successfully joined by friction welding, and the effects of welding parameters on tensile strength and axial shortening were investigated, and welding parameters were optimized using Taguchi method to obtain quality weld joints. The experimental results of the study showed that the highest tensile strength (573.32 MPa) of the joints was 54.53%, higher than the lowest tensile strength (370.99 MPa), the highest axial shortening (23.18 mm) was 650.16%, higher than the lowest axial shortening (3.09 mm). The optimal parameters for average axial shortening and average tensile strength were determined as A3B1C3 and A3B3C2; and the highest percentage contribution values for axial shortening and tensile strength were found to be 51.55% (rotating speed) and 63.90% (rotating speed); and R2 values for the average axial shortening and average tensile strengths were found to be 97% and 99.3%, respectively.

Comparison of the Influence of High-Energy Surface Treatment Methods on Friction and Wear of a 30KhGSN2A Steel (CSN 16532)–30KhGSN2A Steel (CSN 16532) Pair

Comparison of the Influence of High-Energy Surface Treatment Methods on Friction and Wear of a 30KhGSN2A Steel (CSN 16532)–30KhGSN2A Steel (CSN 16532) Pair

The ribbed-annular dome's upper tier model stability experimental studies

Abstract. Purpose. The work’s aim is to check the stability loss hypothesis with the snap-through effect of the ribbed-annular dome's upper tier on a full-scale model by experimental tests, and confirming the nonlinear tier's work under external load. Methodology. The ribbed-ring dome circumscribe in the plan as a circle with a diameter of 18 m with the dome rise ratio to the span - 1/4, which consisted of 8 ribs and had 6 tiers in height, was taken as an dome-model analog.The upper tier of the dome is bounded by the lower ring, which is the upper ring for the tier below, and the dome's upper support ring.Tier rings and ribs are made of steel closed bent welded profiles with rectangular cross section. As a dome's upper tier model, it was decided to use the von-Mises truss as a popular model for two-rod inclined systems' theoretical stability studies, which allows modeling these systems nonlinear behavior. The classic von-Mises truss using in modeling the dome's upper tier behavior is associated with a number of problems.First, the tier is a three-dimensional system with eight rods, so it was decided to model the tier with an equivalent low-pitched truss, which is 1/4 of the upper tier.Secondly, the lower tier ring has limited rigidity and can be deformed, while the classic truss has fixed supports, which is why it was decided to add elastic horizontal supports to the classic von-Mises truss model.Horizontal elastic supports were performed as steel pair puffs and were simulated the dome's upper tier lower support ring deformations. Findings. The obtained data primary and secondary processing, and the full-scale experiment results analysis were carried out. The ribbed-annular dome's upper tier nonlinear deformations nature under the external concentrated vertical load action in the ridge node was confirmed.It was established that in the ridge joint the upper tier's stability loss nature has the snap-through effect. Scientific innovation. The deformation dependencies for the equivalent von-Mises truss with elastic supports with the help of full-scale experimentwere obtained. A comparison of the equivalent truss' behavior experimental studies results with the existing theoretical studies' results was made. The experimental and theoretical studies results analysis confirmed the experimental data results reliability and analytical expressions feasibility use for the preliminary assessment of von-Mises truss' with elastic supports stability. Practical value. The obtained results of experimental research allow creating tools for designers to increase the dome structures reliability.

Resistance Spot Weld Ability of Mild Steel Coated with Zn, Galfan and ZA12

In this study, the weldability of mild steel coated with different Zn-based materials to prevent corrosion with resistance spot welding process was investigated. For this purpose, the surfaces of mid steel were coated with pure Zn, Galfan (Zn5Al) and ZA12 (Zn11Al1Cu) alloys. Hot dipping technique was used for coating. Mild steels with dimension of 1.5X15X40 mm were immersed in the melted Zn and alloys, and the surfaces were coated by waiting for 2 minutes. Steel and coated steel pairs were joined by resistance spot welding process. The welding interface microstructures were examined under light optical microscopy (LOM). Weld interface strengths were measured by axial shear tests. The tests were performed at the room temperature and with a tensile speed of 5mmmin-1. Microstructure investigations showed a good bonding occurred between the coating and the steel and between the welded materials. Mechanical tests have shown that coating the steel reduces the weld strength and the decrease in strength continues with the increase of alloying elements in the coating.

Manual metal arc welding of dissimilar 30MnB5 and S 235 low alloyed steels for agricultural applications

AbstractIn agricultural mechanization industry, different types of materials are assembled with each other to establish agricultural machine systems. However, the necessity of joining dissimilar materials used in the same machine system may cause some problems. Joining two different materials by welding and selecting the most appropriate weld metal (electrode) for this is a very difficult problem. The increasing importance of the economic factors in today’s industry requires both the use of dissimilar materials in agricultural mechanization and the production of longer-lasting agricultural machines, thus making it necessary to use dissimilar steels in agricultural mechanization systems. Therefore, it is important to apply a welding process to dissimilar steels used in agricultural mechanization. In this study, 30MnB5/S235 steel pairs were joined by the manual metal arc welding (MMAW) method using different covered electrodes. In order to determine the mechanical properties of the welded samples, hardness, bending, and impact tests were carried out. In addition, visual inspection to the weld seams, liquid penetrant testing, and metal-lographic examinations to determine the microstructural properties were conducted. As a result of the microstructure studies, structures such as grain boundary ferrite, Widmanstätten ferrite, acicular ferrite, bainite, and martensite were determined in the weld metal and HAZs. As a result of the hardness test, the highest hardness values were determined in HAZs on the side of 30MnB5 steel. As a result of the bending test, the highest mechanical properties were obtained in the weld seams made with basic flux-cored wire. As a result of the notch impact test, the highest mechanical properties were obtained in the weld seams made with basic flux-cored wire, after the base metals.

A New Dual-Mode Wear Model of Abrasion–Fatigue for Plane (100Cr6)-Cylinder (C45E4) Steel Pairs With Fractal Surfaces

Understanding dual-mode wear behavior, including fatigue and abrasive wear, is essential for determination of surface damage under the sliding-impact condition, which can induce early motion-pair failure. A new dual-mode wear model is presented in this article for plane–cylinder contact pairs with fractal surfaces. First, fractal theory is employed for elastic–plastic contact analysis of the mating surfaces. Then the negative inhibitory effect of the abrasive surface damage on subsurface fatigue crack propagation is considered to explore abrasion–fatigue interactions at the asperity level. Subsequently, dual-mode wear behaviors are derived for the asperity and fractal surface based on four wear-combination scenarios of the abrasive and fatigue mechanisms. Furthermore, the validity of the proposed prediction model is evaluated by comparisons between the expected results and laboratory tests with 100Cr6 plane and C45E4 cylinder steel pairs. The results show that the new model can reasonably explain the dual mode wear behavior and predict the wear rate of friction pairs. These insights can potentially help in guiding the tribological design of these dual-mode wear scenarios.