High Wear Research Articles

Investigations on microstructure and properties of five TiZr-based refractory multi-principal element alloys for clinical metallic biomaterials

The development of new materials with high strength, ductility, low modulus, wear resistance, and good biocompatibility remains a requirement in the field of clinical biomaterials. Based on the concept of high-entropy alloys, five TiZr-based refractory multi-principal element alloys (RMPEAs), i.e. MoTiZr, NbTiZr, MoTiVZr, NbTiVZr, and NbMoTiZr were designed and their microstructure, mechanical properties, elastic properties, and biocompatibility were assessed in this study. Results indicate that NbTiZr and NbTiVZr RMPEAs are single-phase BCC alloys, while the other alloys exhibit multiphase structures. In terms of mechanical behaviors, NbMoTiZr RMPEA has the highest hardness (496±15 HV) among the five alloys and also combines a high yield strength and good ductility, with values of 1275 MPa and 21.66%, respectively. According to atomic calculations, the ideal shear strengths of the five alloys on the {110} plane are all lower than those on the {112} plane. Furthermore, NbMoTiZr RMPEA also exhibits a lower Young’s modulus than that of Ti6Al4V, which can reduce “stress shielding” effects. The in vitro biocompatibility evaluation revealed that NbMoTiZr RMPEA can support cell adhesion and proliferation of MC3T3-E1 cells and exhibits good biocompatibility comparable to Ti6Al4V. These results demonstrate the remarkable potential of NbMoTiZr RMPEA for orthopedic bioimplant applications.

Research on self-healing characteristic and state prediction method of the copper based powder metallurgy materials on friction interface

In high power density transmission systems, the friction and wear characteristic of copper based powder metallurgy materials is directly linked to working reliability. Moreover, these materials have frictional self-healing characteristic at the material interface. This paper focuses on exploring the healing mechanism of copper based powder metallurgy materials and conducts ‘damage-healing’ tests, proposing a method to characterize the self-healing characteristic. Subsequently, through comparative tests, the influence of temperature, speed, and pressure on the self-healing characteristics is analyzed. The results show that the increase in temperature reduces the furrow width and depth by 15.30% and 59.76%, respectively. Pressure has the greatest effect on surface roughness, reducing it by 67%. Meanwhile, this paper developed a PSO (Particle Swarm Optimization)-LSTM (Long Short-Term Memory) method to accurately predict the self-healing characterization parameters and self-healing time with small error (average 4.35%) and high correlation coefficient (R 2) (average 0.976). This study contributes to the development of interface repair technology for friction materials.

Preparation, Microstructure, and Mechanical Properties of Al Matrix Composites Reinforced with High‐Entropy Alloys: A Review

Al matrix composites (AMCs) are innovative materials prepared by introducing various reinforcements into Al alloys using suitable processes. Traditional particle‐reinforced AMCs usually have high strength but poor interfacial bonding, resulting in low plasticity. Researchers are attempting to solve this problem by identifying more proper reinforcing particles. High‐entropy alloys (HEAs) with excellent mechanical properties including high strength, ductility, and wear resistance are becoming attractive candidates for the reinforcement of Al alloys. The HEAs‐reinforced AMCs (HEAs@AMCs) combine the lightweight property of Al alloys and superior mechanical properties of HEAs. In this article, a comprehensive overview is provided on the HEAs@AMCs, starting with an introduction to the properties of HEAs, followed by the design principle of HEAs for the metal matrix composites. After that, the preparation, microstructure, and mechanical properties of the HEAs@AMCs are examined. In addition, the effects of HEAs on the microstructure and mechanical properties of the HEAs@AMCs are explored.

The ANALYSIS of the MECHANICAL PROPERTIES of REGIONAL PIPELINES

Piston pumps and compressors are widely used for exploration and transportation of oil and gas. Piston machines are heavy-duty systems that are still failure prone due to high stresses and wear proses. Increasing the efficiency and durability of the piston compressors, pumps, internal combustion engines, etc. directly depends on the correct calculations and designing of these elements. Using ANSYS software, simulation and stress analysis are performed on the basis of the 405GP15/70 and ARIEL heavy-duty balanced opposed piston compressors used in the Caspian Sea-Black Sea Region. During working of the machines and equipment a number of the processes interconnected and causing each other are proceeds (dynamic processes, wear of the interfaced details, change of mechanical properties of materials, etc.). Improvement of modelling of technical condition of cars and mechanisms on a multicriteria basis is one of the actual directions of modern engineering science. The improvement of methods of modelling of change of technical conditions of the piston mechanisms taking into account interrelation of dynamic characteristics, the wear interfaced details and the diagnosed mechanical parameters considered in this article. By observing the analysis results, we can decide whether our designed pipelines are safe or not under applied load conditions. The durable and reliable work of compressor-pump stations used in the oil and gas industry has great importance for practice. Investigation of complex problems with respect to friction and wear (clearances), stresses, and thermodynamics phenomena in the piston machines, and oil and gas pipelines gives the opportunity to solve the problems of increasing the durability of these machines and pipelines. Confirmation that the new methodologies can be produced by the current supply chain improving manufacturing efficiency and reducing the environmental and social impact of the supply chain.

Interface bonding characteristics and thermal damage behavior of brazed diamond with Nb-added Ni[sbnd]Cr filler alloys

NiCr alloy is one of the important filler for brazed diamond tools because of its high hardness, high wear resistance and good wettability to diamond. However, the high brazing temperature and catalytic action of Ni element contained in alloy tend to cause the thermal damage of diamond and interface failure of brazed samples. In this work, the noval NiCr filler alloys added with different contents of Nb are prepared, and the microstructures, mechanical and wear resistance properties of brazed layers used these alloys are investigated. On this basis, the interfacial bonding characteristics and thermal damage behaviors of diamond brazed with Nb-added NiCr filler alloys are further studied. The results show that the addition of Nb element improves the hardness and wear resistance of NiCr filler layer, and the filler alloys exhibit good wettability and climbing effect to diamond. The refined Cr3C2 and Cr7C3 carbides are formed on the surface of diamond, which effectively enhances the interface bonding strength between filler alloy and diamond. Meanwhile, the addition of Nb element consumes some Ni and generates NbNi compound, which weakens, to some extent, the graphitization catalysis and chemical erosion of Ni to diamond. When the addition amounts of Nb are 1–1.2 wt%, the brazed diamond samples present excellent interfacial bonding strength and mechanical properties.

Simultaneously enhanced antioxidation and wear resistance in UHMWPE molded plastic by adding natural polyphenol antioxidant

Ultrahigh-molecular-weight polyethylene (UHMWPE), with its excellent wear resistance and biocompatibility, has important application as artificial joints. The most commonly used method to improve its wear resistance is to introduce crosslinking through irradiation. However, free radicals are introduced after radiation, which are easy to cause inflammation in the human body. Some antioxidants, such as vitamin E (VE), need to be added. However, the addition of VE could reduce the crosslinking density of UHMWPE and worsen the wear resistance of the material. Therefore, obtaining new antioxidants that could eliminate free radicals without affecting or even improving the crosslinking density of materials during irradiation is an important subject worth exploring. In this paper, a kind of natural polyphenol substance, resveratrol (RSV), was introduced as a new antioxidant and crosslinking promoter during irradiation crosslinking of UHMWPE. RSV can better eliminate free radicals than VE and further improve the crosslinking density to obtain UHMWPE materials with excellent oxidation resistance and high wear resistance. The multi-active phenolic hydroxyl structure of RSV molecule provides its free-radical trapping ability, and the appropriate molecular size of RSV may promote the H-type crosslinking of UHMWPE, thereby increasing the crosslinking density. This work provides a new pathway for developing high-performance artificial joint prosthesis materials.

Evolution of interfacial nanostructures with temperature governing fretting wear in diamond-like carbon films

Diamond-like carbon (DLC) films are capable of offering low friction coefficient and high wear resistance when rubbed in both dry and lubricated interfaces. However, the inherent mechanisms governing fretting wear in DLC films with temperature are still not well comprehended. Herein, atomic-scale analysis was conducted to unveil the relationship between interfacial tribofilms and the fretting wear behaviors. The results emphasize the determining role of the interaction between the tribo-sintered tribofilms and the transferred carbon tribofilms, as well as the structural evolution in the DLC film with temperature. The room temperature (RT) fretting experiment establishes a bilayer nanostructured tribofilm with a C-rich transfer layer on a Fe-rich tribo-sintered layer. As the fretting temperature elevates the graphitization degree of the tribofilms exacerbates, surface oxidation and hydrogen effusion arise in the DLC film, resulting in higher friction coefficients and wear rates. Chromium outward diffusion at 500 °C establishes a Cr-rich interlayer in the tribofilm, which forms interfacial chromium-carbon bonds, promotes adhesive carbon transfer, and leads to the sharp increase of the friction force and wear rate. These findings provide new insights into the fretting wear mechanisms, and provide guidance for the application of DLC films in elevated-temperature fretting scenarios such as aero-engines tenon and spline connections.

The Prevalence of Tooth Wear and Their Associated Etiologies Among Adult Subjects Visiting Umm Al-Qura University Dental Clinic in Makkah City, Saudi Arabia.

In the past two decades, changing trends in socioeconomic status, dietary habits, and individual lifestyles of individuals have led to the emergence of tooth wear as an oral health problem. The present study aimed to investigate the prevalence and the associated etiologies of tooth wear in a convenience sample of adult patients visiting outpatient clinics of the Faculty of Dentistry at Umm Al-Qura University. This cross-sectional study was conducted on adult patients (18-40 years old) visiting outpatient clinics of the Faculty of Dentistry, Umm Al-Qura University. Two trained examiners visually assessed patients' tooth wear using Smith and Knight's Tooth Wear Index (TWI). Following the clinical examination, patients completed a self-administered questionnaire detailing risk factors such as the frequency of intake of acidic food and medicines, general health, chewing habits, dietary factors, and oral health-associated preventive behaviors. The resulting collected data were tabulated and statistically analyzed using Statistical Product and Service Solutions (SPSS, version 21; IBM SPSS Statistics for Windows, Armonk, NY). The total prevalence of tooth wear was 74%, and the recorded mean wear score (TWI) was 0.380 ± 0.386; anterior teeth exhibited greater wear than posterior teeth. Numerous associations were recorded between tooth wear and the tested variables in demographics, habits, diet, and medications, but most of them were not statistically significant. When toothbrushing habits were explored, the only factors to played a significant role in abrading the tooth structure were the type of brush bristles used (P-value = 0.026) and the frequency of brush renewal (P = 0.043). Patients who frequently ate citrus fruits and other acidic foods recorded high wear scores (0.509 ± 0.311 and 0.508 ± 0.402, respectively), although the difference was not statistically significant. When chewing occurred on both sides of the mouth, less tooth wear was recorded than if chewing was on the right or left side only (0.371 ± 0.260, 0.422 ± 0.273, and 0.520 ± 0.419, respectively). The study data support an association between tooth wear and patient occupation, use of hard-bristled and new toothbrushes, eating of citrus and other acidic food, and chewing on one side, as all of these factors increased the risk of tooth wear.

STRUCTURE AND PROPERTIES OF SELF-LUBRICATING COPPER-NICKEL-GRAPHITE COATING FABRICATED USING COLD SPRAY

Application of self-lubricating Cu-matrix coatings is an attractive way to provide high electrical conductivity and wear performance in contact friction pairs in various areas of modern engineering. In the present work, the structure and properties of self-lubricating copper-nickel-graphite coating deposited on copper substrate using high-pressure cold spray were studied for the first time. The coating was fabricated by spraying dendritic copper and flaked nickel-coated graphite powders mixed in a ratio 70/30 wt.%, which ensured the formation of a lamellar structure. The obtained coating exhibited an attractive combination of hardness (108.8 HV1), coefficient of friction (0.34) and electrical conductivity (43.8 % IACS), which open prospects for its electrical applications.

On the influence of iron and silicon content on the phase composition of the Al-Fe-Si system

Increasing interest in intermetallic phases of the Al-Fe-Si system is associated with their high specific strength, corrosion and wear resistance, as well as the low cost of their production. To exhibit the most successful combination of properties, it is necessary to impart a specific compact morphology to the precipitated intermetallic phases. It is important to create an alloy with a composition capable of accepting plastic deformation. The purpose of the work is to develop the composition of an Al-Fe-Si system alloy capable of withstanding plastic deformation and determining the corresponding deformation interval. Based on computer modeling, an alloy composition capable of accepting plastic deformation was developed and the corresponding deformation interval was determined. The simulation was carried out in the ThermoCalc software package, TCAL8 database. It has been revealed that alloys with a high content of both silicon and iron are not characterized by the formation of a single-phase region, however, with a certain combination of alloy components, it is possible to achieve a quasi-single-phase structure, when the content of one phase is observed to be more than 90%. The solidus temperatures for different alloy compositions and the boundary conditions for the existence of phases have been determined. The α phase is present in the system from a temperature of 770°C up to a temperature of 446°C. In composition, it is found in the range from 5 to 35% iron with an amount of silicon of 10% and from 0 to 15% silicon with an iron content of 30%. The maximum amount of α phase was obtained for the Al60-65 alloy; Fe30-32; and Si5-10%, deformation temperature range is 600-450°C. Deformation in this region will ensure processing in a quasi-single-phase region without melting.

Machinability of waste bamboo powder ash reinforced 7075-T651/B4C Hybrid composite in computer numerical control lathe

Metal Matrix Composites (MMC) are novelly prepared with the reinforcement of different wood ash in the matrix material to achieve desired properties. Utilizing the waste material for reinforcement may reduce the material cost. Usually, fly ash from thermal power plants has become a popular reinforcement material for MMC through stir casting and employing in friction stir processing. This research is motivated by using ash of waste bamboo powder (AWBP). The waste of bamboo pieces was collected from the furniture industry. They have been gathered, prepared to ash and used as reinforcement of 4 wt%, 8 wt%, and 10 wt% in stir casting of aluminium alloy 7075-T651 and that was optimized as 8 %. The objective of this research is CNC turning type machinability of AA7075-T651/ B4C/AWBP hybrid Composites. The details of the reinforcement are 2 wt% B4C and 8 wt% AWBP. The effects of such reinforcement in AA7075-T651/ B4C/AWBP hybrid composite have improved the friction and wear behaviours, such as high wear resistance and low wear rate. The composite was cased as circular rods. The CNC turning type machinability was investigated in the CNC turning centre. The cutting speed varied from 1000 rpm to 3500 rpm, the feed rate varied from 100 mm per hour to 200 mm per hour. The Al2O3 nanoparticles concentration on cutting fluids varied from 0.25 wt% to 1 wt%. The response surface methodology was used to optimize the parameters. A mathematical model was developed to predict the responses.

Agglomeration behaviors of different types of complex TiN inclusions in high titanium wear resistant steel

Large-sized titanium-containing inclusion clusters seriously affect the continuous casting and performance of high titanium wear-resistant steel. In the current work, thermodynamic calculations were firstly conducted to predict the formation of various complex TiN inclusions, viz, TiOx-TiN, Al2O3–TiN and LaAlO3–TiN. Based on that, laboratory-scale experiments were designed to prepare samples containing a single type of complex TiN inclusions. The agglomeration characterizes of different complex inclusions were compared by combing in-situ observation based on confocal laser scanning microscopy and Newtonian motion equation. Furthermore, the Kralchevsky-Paunov model was used to study the influences of density and size on the agglomeration behavior of complex TiN inclusions. The result shows that the attractive force between TiOx-TiN complex inclusions increases from 1.93 × 10−18 to 4.34 × 10−17 N, while it was 3.41 × 10−17 to 5.12 × 10−16 N for Al2O3–TiN complex inclusions and 6.42 × 10−18 to 1.14 × 10−16 N for LaAlO3–TiN inclusions. Based on the experimental results and theoretical calculation, the agglomeration tendency of Al2O3–TiN is the strongest due to the considered size and compared to the TiOx-TiN inclusions, the stronger agglomeration tendency of LaAlO3–TiN ones can be attributed to their higher density.

Technological progress in Russian military sports suits: the history of the use of materials and fabrics from the end of the 19th century to the beginning of the 21st century

The subject of the study is technology in military sports suits of Russian military personnel. The object of the study is the progress in the production technologies of military sports suits. The author examines in detail the history of the use of various materials and fabrics for the production of military sports suits, from the end of the 19th century to the beginning of the 21st century. Special attention is paid to the analysis of the properties of various materials. The author shows that fabrics with high strength, wear resistance and good breathability are most suitable for military sports suits of Russian servicemen. The fabrics used for the production of military uniforms must meet a number of requirements. At the same time, such properties of fabrics as crease, drapery, hydroscopicity, dust capacity, heat-shielding properties, shrinkage, thread shedding, thread expansion in seams, sliding should be taken into account. The main research methods were theoretical methods – the method of analysis, generalization, systematization, classification of literary sources on the research topic. The novelty of the research consists in a comprehensive analysis of the basic properties, characteristics and requirements for fabrics used for the manufacture of military suits. A retrospective analysis and comparison of costumes from different eras were carried out. The main conclusion of the study is that from the end of the 19th century to the 21st century, the use of fabrics for military clothing has undergone significant changes. It is shown that at the end of the 19th century, military clothing was mainly made from natural fabrics such as cotton, wool and linen. With the advent of synthetic fibers in the 20th century, fabrics became more durable, lightweight, quick-drying and resistant to external factors. In the 21st century, with the development of fabric production technologies for military clothing, special mixtures of natural and synthetic fibers, as well as membrane materials, began to be used to provide high protection, comfort and functionality for military personnel. The author's special contribution to the study is the generalization of the results of various studies, the comparison of the main characteristics of fabrics used in various historical times with modern fabrics and materials.

Understanding DLC system failure influenced by progressed wear

Diamond-like carbon (DLC) coatings are among the toughest and most effective measures for preventing wear on critical surfaces. Due to its high wear resistance, the deterioration of the protective coating only occurs upon failure. Understanding the events leading to failure and identifying a mild-abrasive wear process is crucial for sustainable application. We implemented a ‘Wöhler-like’ test matrix on a tribometer with oscillating tribocontact, employing radioactive isotopes for continuous wear measurements. This method allows to analyse the relationship between load and cycling or test time. When combined with friction coefficient changes, it enables the distinction between mild and severe wear, ultimately pinpointing the point of DLC deterioration. This approach was employed to compare different diesel lubricants, and its effectiveness was demonstrated. The relationship between loading condition and remaining DLC thickness illustrates that mild-abrasive wear is the critical factor for DLC lifetime, ultimately leading to coating system failure.

Si-enabled self-lubrication and wear resistance of CrCoNiSi medium-entropy alloy films

High- or medium-entropy alloys have gained attention in coatings attributed to high wear resistance, with the formation of an amorphous phase. However, tailoring the crystal structure has limitations in improving both friction and wear characteristics due to the uncertain influence of amorphization on friction coefficients. In this respect, Si, known to increase glass-forming ability, can reduce the friction coefficient as a self-lubricating tribo-film formed by tribochemical reactions. However, tailoring Si content also affects crystal structures, defects, and mechanical properties, which require systematical investigations. Therefore, in this study, CrCoNiSi alloy films are fabricated with controlling Si content (0–13 at%) and sputtering power (5.8–13.7 W/cm2). The increase in Si content and sputtering power both produce identical microstructural evolutions, shifting from a crystalline towards an amorphous phase. In an amorphous film of high sputtering power, the high SiO2 fraction leads to dominant adhesive wear with delamination, thus contributing to the increase in wear rate. However, the Si addition alters the Si ion fraction of post-wear, forming Si-induced tribo-film, retaining abrasive wear, and consequently reducing the friction coefficient and wear rate. This Si addition would offer control over crystal structure and self-lubricating properties, enabling tailored mechanical and tribological properties.

Insights into medieval rural lives: A paleo-odontological investigation of two central European communities

ObjectiveOral status is an important indicator of past lifestyles. Determining the presence and extent of oral pathologies helps reconstruct average oral health, paramasticatory activities and diet of ancient and historical populations. DesignIn this study, the dental remains from the early medieval cemetery of Früebergstrasse in Baar (Canton of Zug, Switzerland) and the high medieval Dalheim cemetery (North Rhine-Westphalia, Germany) were analyzed. Caries, periodontal condition, periapical lesions, antemortem tooth loss, and enamel hypoplasia were assessed in 654 teeth (993 observable loci) from 68 individuals (Baar: n = 36; Dalheim: n = 32). ResultsThe oral status of both populations was affected by age with higher values of tooth wear in advanced age individuals. High tooth wear values in both populations point towards the consumption of abrasive foods. Pronounced anterior tooth wear in Baar may also be due to non-masticatory tooth usage. Finally, possible nutritional deficiencies were hypothesized for the Baar population. A higher caries prevalence was observed in the Baar group, probably due to differences in carbohydrate intake. The oral conditions observed in the two studied populations exhibited several analogies, suggesting comparable lifestyles despite their separation in space and time. The only differences observed are related to the use of teeth as “tools” and are thus determined by behavioral choices rather than diverse socioeconomic factors. ConclusionsUsing multiple dental parameters to examine the oral health of premodern individuals can provide useful insights into the interactions between humans and their environment, from dietary patterns to paramasticatory activities.

PRODUCTION OF Ni-HARD ALLOY POWDERS BY GAS ATOMIZATION

Ni-Hard cast iron materials are frequently used in equipment where high wear resistance is required in industrial applications. Generally, Ni-Hard is produced by conventional casting techniques. In this study, it was aimed to produce Ni-Hard powders to produce Ni-Hard cast iron materials with additive manufacturing techniques. To produce spherical and fine raw materials for additive manufacturing techniques, the gas atomization technique with a close-coupled nozzle system was preferred for the production of Ni-Hard powders. Ni-Hard alloy was melted in a high-frequency 10kW induction furnace under a protective atmosphere integrated into the gas atomization system. During the atomization process, 150 °C superheating was applied to prevent the liquid metal from freezing and clogging the melt delivery tube. In terms of the continuity of the atomization process, the negative pressure (aspiration pressure) values formed at the end of the melt delivery tube at different gas pressures were measured. An aspiration pressure of -50 mbar was obtained under an atomization pressure of 35 bar. Particle size distributions, hall flow behaviour and angle of repose properties of the produced powders were determined. Finally, the characterization of the powders was carried out by scanning electron microscopy. It was determined that the powders obtained as a result of atomization exhibited a spherical morphology and a narrow size range. The Hall flow rate test result of Ni-Hard powders was measured as 22 seconds for 50 g.

Effect of Various Sintering Temperatures on the Friction and Mechanical Properties of PEEK/PTFE Blends

Polytetrafluoroethylene (PTFE) has a very low coefficient of friction and outstanding corrosion resistance, but its limited use is due to high wear and tear and low hardness. Polyetheretherketone (PEEK) offers low wear, high temperature resistance and a slightly higher coefficient of friction. In the research we describe here we examined the mechanical and tribological properties of PEEK/PTFE blends manufactured at various sintering temperatures (350 °C–390 °C). The experimental data demonstrated that the PEEK/PTFE blends exhibited the highest tensile strength, 22.97 Mpa, when sintered at 380 °C, making them the most resistant to breaking or deforming. The elongation at break increased with the increase of sintering temperature, and the highest value of elongation at break for the PEEK/PTFE blends was 429.16% when sintered at 390 °C, and the lowest value was 283.37% when sintered at 350 °C. The PEEK/PTFE blends exhibited the lowest coefficient of friction, measuring 0.174, when sintered at 350 °C. The lowest mass abrasion rate for the PEEK/PTFE blends was 6.04 × 10−7 mm3/N·m when sintered at 360 °C.

Hydrogen permeation resistance of ZrN thin film deposited by ion-plating

Hydrogen absorption of Zircaloy nuclear fuel cladding, used in light water reactor at nuclear power plants, poses an increased risk of delayed hydride cracking during interim dry storage. Consequently, novel surface technologies aimed at reducing hydrogen absorption have become a critical area of research. Zirconium nitride coatings, renowned for their high hardness, corrosion resistance, and wear resistance, have seen widespread application in various industries, including medical devices, cutting tools, and decoration. This study explores the effectiveness of ZrN coating in suppressing hydride formation in Zircaloy-4, a material commonly used for nuclear fuel cladding. In this research, ZrN coatings were deposited onto recrystallized Zircaloy-4 substrates using a hollow cathode discharge ion-plating (HCD-IP) system. The coated and uncoated Zircaloy-4 samples were then subjected to electrochemical and gaseous hydriding processes. The study further investigates the differences in microstructure and hydrogen content of coated and uncoated Zircaloy-4. From these results, it is evident that the ZrN thin film deposited by HCD-IP exhibited great resistance to hydrogen permeation against both hydriding conditions. It is concluded that the ZrN thin films can serve as an excellent hydrogen barrier layer for Zircaloy-4.

Microstructural Investigations of Weld Deposits from Manganese Austenitic Alloy on X2CrNiMoN22-5-3 Duplex Stainless Steel

Duplex stainless steels are materials with high performance under mechanical stress and stress corrosion in chloride ion environments. Despite being used in many new applications such as components for offshore drilling platforms as well as in the chemical and petrochemical industry, the automotive industry, etc., they face issues of wear and hardness that limit current applications and prevent the creation of new use opportunities. To address these shortcomings, it is proposed to develop a hardfacing process by a special welding technique using a universal TIG source adapted for manual welding with a pulsed current, and a manganese austenitic alloy electrode as filler material. The opportunity to deposit layers of manganese austenitic steel through welding creates advantages related to the possibility of achieving high mechanical characteristics of this steel exclusively in the working area of the part, while the substrate material will not undergo significant changes in chemical composition. As a result of the high strain hardening rate, assisted mainly by mechanical twinning, manganese austenitic alloys having a face-centered cubic crystal lattice (f.c.c) and low stacking fault energy (SFE = 20–40 mJ/m2) at room temperature, exhibit high wear resistance and exceptional toughness. Following cold deformation, the hardness of the deposited metal increases to 465 HV5–490 HV5. The microstructural characteristics were investigated through optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and Vickers hardness measurements (HV). The obtained results highlighted the feasibility of forming hard coatings on duplex stainless steel substrates.