Papers by Keyword: Wear

Abstract: Various steels with suitable properties can be used as barrel steel. Most of the steels intended for the production of barrels are low or medium alloy steels. Barrel steels are significantly stressed by high pressures and temperatures during firing. During the shot, various forms of wear occur in the barrels, mostly abrasive, adhesive, and erosive wear. One of the most widely used steels for greater traction, from which barrels are made, is 34CrNiMo6. This steel is normally used for larger calibers, such as artillery, or for more stressed small-caliber weapons. This steel and its derivatives are the most widely used steels for the production of highly stressed barrels. We subjected the 34CrNiMo6 steel to tribological tests. In this article, we evaluated the coefficient of friction between 34CrNiMo6 steel and a G40 bearing ball. All measurements were performed on a UMT TriboLab universal tribo-meter (TA Instruments, New Castle, Delaware, USA) in dry conditions. The main goal of the experiments was to analyze the friction properties and wear of steel for the production of stressed 34CrNiMo6 barrels in contact with a G40 bearing ball with a diameter of 6.35 mm. In this evaluation of measurements, the authors of the article focused mainly on the influence of the peripheral speed on the change in wear and the coefficient of friction for two types of surfaces.

Abstract: Gear wear is the main factor affecting their performance and service life. In addition to the accuracy of production, the quality of the material from which the gears are made also depends on the degree of wear. The article compares the material properties of gears of JAWA motorcycle transmissions. In addition to the original gears, produced at that time in Czechoslovakia, the market also offers gears that are produced today, originally from the Czech Republic and Taiwan. Since the only comparable indicator is their price difference, the question arose whether the new variants can compete with the original part in terms of quality of workmanship. For this finding, the gears were subjected to wear tests and determination of the hardness of the material with the devices intended for this. In this way, valuable data will be obtained that will contribute to a better understanding of the performance and lifetime of these components. The quality of workmanship as well as the price are factors that should always be considered before the final selection of the item.

Abstract: Advanced high-strength steels (AHSS) have their current applications directed mainly to the automotive industry, where they use modern metallurgical techniques to develop microstructures with retained austenite, which leads to an improvement in the combination of strength and ductility through transformation-induced-plasticity (TRIP). The main priority of the research work will be a detailed examination and optimization of the heat treatment parameters of medium-manganese steels, specifically by the Quenching and Partitioning (Q&P) method and the expansion of experimental data related to the increase of wear resistance of these materials. The issue of the application of medium-manganese high-strength AHSS steels in the field of tribology is currently very relevant. Mid-manganese AHSS steels, which show significant wear resistance, have the potential to replace traditional Hadfield Mn steels that contain 10-14 wt. % manganese. With the help of specifically designed heating and cooling cycles, it is possible to improve their wear resistance through metastable retained austenite, which has significant potential in demanding industrial environments. This scientific study examines the possibilities of increasing the economic efficiency of the production and use of AHSS steels in various industrial areas and at the same time reducing costs compared to expensive wear-resistant steels. A key aspect of the research is the experimental evaluation of heat treatment optimization to maximize resistance to mechanical damage and extend the life of materials in various applications.

Abstract: In this paper, the steels used in MN knife mills, which are used for plastic recycling, are investigated. 90MnCrV8 steel is commonly used in these mills, which will be replaced by X153CrMoV12 steel. The main goal of the presented contribution is to perform tribological tests and verify the wear rate of both steels experimentally with subsequent practical verification in the knife mill MN. Partial results relate to the analysis of hardness, roughness, and overall wear mechanism. A hardened steel ball of material G40 with a diameter of 4.76 mm was used as the contact material. The steel ball performed reciprocal linear motion on the surface of the experimental materials at room temperature and without the use of lubrication. The measurements were carried out in three-time intervals of 20, 30 and 40 min. The experimental material X153CrMoV12 can fully replace the material 90MnCrV8 in processes where its degradation occurs due to the friction mechanism. The material X153CrMoV12 showed significantly better results in all the values ​​we measured. It can be expected that the knife in the MN knife mill made of X153CrMoV12 steel will last several times longer in the working environment, which was also proven by practical verification in production.

Abstract: This paper discusses the wear behavior of self-mated AISI52100 bearing steel lubricated by polyol ester containing additives of bacterial cellulose particles. The wear properties are compared to those of surfaces lubricated by the base fluid without the additive. The sliding tests were conducted using a pin-on-disk reciprocating tribometer at room temperature. The results indicate that after a sliding distance of 72 meters, the friction coefficient was relatively similar for both lubricant conditions. However, the wear of the material was significantly reduced with the presence of cellulose particles in the lubricant, improving it by almost 100%. Observation of the worn area of the pin indicates the formation of a tribofilm on the contact interface facilitated by the cellulose particles. EDX analysis revealed that the film comprises oxygen and carbon-rich elements. It seems that the tribo-layer formed by a tribo-chemical reaction during sliding has acted as a protective barrier, preventing surface material ploughing and reducing wear on the tribo-pair.

Abstract: The processing of metallic materials alone has a huge impact on resource utilization, emission, and waste generation. With the emergent ecological concerns, there is a solid thrust towards sustainable materials development. Sustainable metal matrix composites are designed to minimize environmental impacts by reducing resource consumption and energy usage and curbing waste generation. Now a days, the automotive sector is making significant strides towards a more ecological product chain by adopting sustainable reinforcements such as basalt fibres, red mud reinforcements, fly ash, cenosphere particles etc. into matrix material which significantly influence the mechanical properties. With this perspective, the present work is aimed to investigate the hardness, tensile, flexural, impact and wear characteristics of 7075 reinforced with different combinations of B4C, egg shell particles along with fly ash. The results revealed that the best mechanical and wear are measured at 3 % boron carbide, 3 % Egg shell powder and 2 % fly ash reinforced AA-7075 composite among the other developed composites. The results thus suggested that the incorporation of sustainable reinforcements along with ceramic reinforcements offer enhanced material characteristics, cost savings and environmental advantages.

Abstract: To reduce emissions in the mobility sector, demand for high-strength and higher-strength steels in the automotive sector is constantly increasing, and with it the demands on the tools of the sheet metal processing industry. One important phenomenon is rapid wear which reduces the service life of blanking tools. Compensating with an increased use of lubricants is not advisable from an ecological point of view. It could be shown in literature that through texturing the lateral surfaces of blanking tools their wear behavior can be improved. In this work, machine hammer peening (MHP) was used to texture the surfaces. Compared to other deterministic texturing methods such as laser texturing, MHP has several beneficial effects. No additional surface finish is required after texturing and the surface structure is not weakened by the thermal influence. MHP machining simultaneously induces residual compressive stresses close to the surface, work-hardens the edge zone and smoothes roughness peaks. Combined with deterministic texturing in the same process step, the tribological behavior of the tool surface can be significantly improved. Based on the tribological investigations of the authors in the strip drawing test on different structuring strategies, the findings from the model test are to be transferred to the real test in this work. For this purpose, rotationally symmetrical blanking punches were textured using a specially developed texturing center. The machine hammer peening center allows surface texturing with positioning accuracies of less than 2% by controlling a rotary and feed axis in combination with frequency control of the machine hammer peening set up. A hammer head with micro-milled micro-tip was used as the texturing tool for the MHP. Different degrees of coverage with the same aspect ratio were applied to the surface. These punches were then tested on various materials on an industrial high-speed stamping press. To evaluate the effectiveness, the force curves for different blanking frequencies were analyzed and the evolution of the textured topography was continuously evaluated. The experiments reveal that the withdraw force could be reduced by 38% due to the micro texturing with a coverage of 18%. Other coverages led to an increase. By texturing the lateral surfaces of blanking punches using MHP the service life could also be significantly improved.

Abstract: Hydro turbines are the key features of the developing globe for utilizing one of the important renewable energies, namely hydro power. The longevity of these hydro machineries links directly to the surface properties of critical component like impellers, as these components are exposed to slurry and cavitation erosion during their use and should be addressed by the properly designed material surfaces for consistent efficiency. The surface properties can be altered and improved by developing coating in conventional steels that are used for impellers. A recommended hard coating for such applications involves titanium carbide (TiC) with Ni and Cr binders. Along with hardness, an increase in surface hydrophobicity can also reduce wear. High velocity oxygen fuel (HVOF) spraying process comes under the umbrella of thermal spray process that utilizes melting of powders via burning of fuel and these molten powders were bombarded on the surface with supersonic velocity to generate a coating. In this paper, HVOF thermal sprayed coating consisting of TiC and NiCr has been utilized for SS410 steel. In addition, a thin layer of polytetrafluoroethylene (PTFE) has also been investigated on the HVOF sprayed surface to enhance its hydrophobicity. The developed surface has been characterized by static contact angle, hardness, porosity, surface roughness, and coating thickness. Variable impingement parameters, namely sand concentration (20000 & 40000 ppm), angle of impingement (45 & 90°) for slurry testing, stand-off-distance (4 & 8 cm), and flow velocity (15 and 30 m/sec) for cavitation testing were opted for analysis the wear resistance of candidate specimens. From the results, it has been observed that the implementation of a PTFE layer leads to super hydrophobicity. However, the hardness and surface roughness have been reduced with the assistance of PTFE layer. Meanwhile, the slurry and cavitation erosion resistance were also found to be improved by the PTFE layer due to the increase in static contact angle. In the case of cavitation erosion, maximum jet velocity and stand-off distance contribute to more wear, owing to sufficient bubble generation. Next, in case of slurry erosion testing, mixed aspect of erosion wear with respect of influence of parameters was observed for coated and uncoated samples. Ductile mode of failure was observed for SS410, and PTFE sprayed specimens, on the other side, HVOF sprayed TiC+50%NiCr coating showed mixed mode of erosion.

Abstract: This paper addresses the unique challenges in processing aluminum materials within metal forming technology, specifically focusing on complex wear conditions involving abrasion and adhesion. A promising research approach to avoid abrasive and adhesive tool wear and reduce the friction coefficient towards aluminum alloys is the use of sufficiently smooth CVD diamond coatings. To achieve this, two approaches are considered. First, wear resistance is enhanced by using tool inserts made of carbide or a tungsten alloy, directly coated with CVD diamond. Second, the friction coefficient is selectively influenced or reduced by refining the polished CVD diamond coating through laser ablation. The study investigates the impact of these surface treatments on friction coefficients during both dry and lubricated forming processes involving the aluminum alloy EN AW-5182. Comparative analyses of various surface treatments are conducted against reference tests using diamond-like carbon (DLC)-coated tools. Through application-oriented strip drawing tests, the paper systematically examines how different surface smoothing techniques affect the coefficient of friction. This research provides valuable insights into optimizing metal forming processes for aluminum alloys through tailored surface treatments, advancing our understanding of friction dynamics in these specific manufacturing conditions.

Abstract: This study analyzes the wear mechanisms of a Kevlar-Zirconia-Epoxy composite casing coating under varying drillpipe joint speeds and side loads, using both dry and water-based mud lubrications. Employing Scanning Electron Microscopy, the research highlights the influence of ceramic microfillers on the wear characteristics. Findings indicate that abrasive wear dominates at low speeds, while higher speeds increase adhesive wear. Side load changes had minimal impact on wear mechanisms. Additionally, specimen temperature significantly affects composite behavior, underscoring the importance of lubrication for maintaining composite integrity. The results suggest this composite is well-suited for applications requiring high durability and wear resistance.