Surface Hardening Research Articles

Unveiling the effect of electron beam shock on the microstructure and wear resistance of Cr12MoV steel

Enhancing wear resistance is the core factor that prolonged the life of the Cr12MoV mold and elevates the quality of the components produced. Hence, Cr12MoV mold steel was shocked by scanning electron beam (SEB) to improve wear resistance. Results revealed that the segregation eutectic carbides in the surface structure of Cr12MoV steel were dissolved during the shock process of various beam electron beams, and the small particles of carbides produced are helpful in reducing wear. With an energy density of 20 J/mm2, surface roughness of Cr12MoV steel decreases from 2.9 μm to 1.2 μm, the friction coefficient decreases from 0.85 to 0.52. Additionally, the wear capacity also decreases from 0.036 mm3 to 0.011 mm3, and surface wear resistance increases by over 3 times. Grain refinement-induced surface hardening is the primary cause underlying performance improvement. This study provides ideas for improving the surface quality of Cr12MoV steel.

Enhancing durability and sustainability of industrial floors: A comparative analysis of dry-shake surface hardeners

This study investigates the development of a cost-effective and sustainable dry-shake surface hardener for enhancing the durability of industrial concrete floors. Utilizing locally sourced materials, the research aimed at not only ensuring the hardener's strength and finish but also its economic viability and environmental friendliness. Fourteen unique mixtures were formulated by altering the sand ratios and incorporating superplasticizers to optimize the composition. These mixtures underwent rigorous testing over 7, 14, and 28 days, evaluating their compressive and flexural strengths, flowability, water absorption, and impact resistance. The findings revealed that the modified floor hardener, specifically the FH-12 mixture, exhibited superior performance across all tested parameters. It showed higher compressive and flexural strengths, enhanced impact resistance, and reduced water absorption compared to other variants and commercially available hardeners. Notably, the use of finer coarse sand and the adjustment of superplasticizer quantities significantly contributed to these outcomes. This breakthrough demonstrates the potential of employing locally available materials to create a durable, cost-effective, and environmentally friendly solution for industrial flooring. The study underscores the importance of material characterization and methodical formulation in developing construction materials that meet the dual criteria of performance and sustainability. This option is preferred for its lower environmental impact and compatibility with sustainable practices, contributing to Sustainable Development Goal 9 on industry, innovation, and infrastructure. It highlights the role of floor hardeners in global sustainability efforts.

AN ENHANCEMENT IN THE COPPER ELECTRODE WEAR CHARACTERISTIC ELECTRICAL DISCHARGE MACHINED INCONEL 718 THROUGH ION NITRIDING, LASER SURFACE HARDENING AND HYBRID PROCESS

The virgin copper electrode has limited application due to its wear and mechanical properties using Electrical Discharge Machined (EDMed) on Inconel 718 superalloys. In order to enhance the performance of copper electrodes, in this work, Ion Nitriding (IN), Surface Hardening by Laser (LSH) and Hybrid Process ([Formula: see text]) are performed on copper electrodes to reduce the electrode wear in frontal and lateral. The electrode wear in the frontal and lateral of virgin copper electrode is processed and studied using EDM with varying pulse durations, current and Silicon Carbide (SiC) mixed EDM oil. The surface hardness in virgin and processed electrodes is also investigated. Overall analysis found that the hybrid technique produced a 59% higher hardness than that of virgin copper. The hardness in the EDMed surface was higher than that of the processed copper surface. A 1000[Formula: see text][Formula: see text]s pulse duration, 2 A current and 15 g/l SiC powder mixing EDM oil produced a low frontal wear in both virgin and processed copper electrodes. The electrode wear was reduced by 30% for frontal and 76% for lateral using a hybrid method.

Catalysis effect of rare earth element Ce on paste boriding treatment of AISI 410 steel

Abstract Surface hardening techniques of steel are of great practical interest for applications in various industrial sectors. Boriding is one of the most economical choices. However, the chief deterrent to the widespread application of the technique is the difficulty in attaining a thick, dense boride layer. To solve this problem, a paste boriding process was performed on the surface of AISI 410 steel by introducing 6 wt.% CeO2 addition into the boriding agent. The microstructure of the boride layer is comprised of (Fe, Cr)B and (Fe, Cr)2B, which lie in the external and internal layers of the boride layer, respectively. CeO2 addition makes it possible to prepare a thick, dense boride layer on the surface of the steel substrate, thereby improving both wear and corrosion resistance of the steel. The catalysis mechanism of the rare earth element Ce can be ascribed to three aspects. First, CeO2 addition can take part in the chemical reactions involved in the boriding process to produce more active boron atoms. Second, Ce can facilitate the adsorption of active boron atoms onto the surface of the steel through preventing the formation of iron oxides on the steel’s surface. Third, Ce can diffuse into the surface of the steel and generate severe lattice distortion due to large atomic size, thereby promoting the boron diffusion. These results provide a high-quality, low-cost pathway for the surface hardening of steel in practical industrial applications.

Effect of duplex surface treatment on the impact properties of maraging steel produced by laser powder bed fusion

The impact properties of an L-PBF 18Ni-300 maraging steel were investigated after different heat and duplex (nitriding and PVD coating) surface treatments. Impact energy is almost isotropic. Contrary to expectations, impact energy is not decreased by surface treatments, since the effect of surface embrittlement of nitriding is compensated by the increase in the austenite content. An important role is played by the geometry of the notch where the surface hardening is lower than in the flat surface of the Charpy specimens.

Effect of electropolishing on ultrasonic cavitation in hybrid post-processing of additively manufactured metal surfaces

This investigation centered on fundamental understanding of a hybrid post-processing method that synergistically combines electrochemical polishing and ultrasonic cavitation to improve the surface roughness and mechanical properties of additively manufactured parts efficiently and simultaneously in a single step. High-speed imaging was utilized to understand the effect of the DC bias applied during electropolishing on the cavitation generated at various ultrasonic amplitudes. This was aimed at validating the hypothesis that the hybrid process is characterized by more bubbles than with ultrasonic excitation alone, and, in the presence of the DC bias, the bubbles are transported from the cathode to the anode (workpiece) where their impacts cause surface hardening. High-speed imaging confirmed a higher bubble count in the hybrid process than in the cavitation-only process at different ultrasonic amplitudes. Microhardness measurements confirmed that the hybrid process yielded higher microhardness compared to cavitation peening alone, while microhardness in electrochemical polishing showed only incremental changes. This observation was also corroborated by the grain size measurements, with the hybrid process exhibiting more grain refinement than cavitation-only or electropolishing-only post-processing modes. Surface topography analysis revealed minimal improvement in surface roughness due to cavitation-only, emphasizing the importance of the hybrid process in enhancing both surface roughness and the mechanical properties. Scanning electron microscope (SEM) images showed randomly distributed micro-dimples on the surface produced by the hybrid process at the highest ultrasonic amplitude, attributed to the increased number of cavitation bubbles. This research provides fundamental insights into why the hybrid process excels in simultaneously reducing surface roughness and achieving superior surface microhardness.

Enhancing steel properties with surface mechanical treatments

This research presents the modification of the microstructure on the surface of a dual phase steel (DP) using three different treatments: surface mechanical attrition treatment (SMAT), surface mechanical carburizing treatment (SMCT), and surface mechanical composite coating treatment (SMCCT). We used SMAT to refine the grain size under high strain and strain rate conditions and successfully induced a phase transformation to martensite. The introduction of carbon during SMAT resulted in surface mechano-chemical carburizing, which enhanced the martensite transformation. Furthermore, the addition of silicon during the process led to the formation of SiC and Fe3C particles dispersed within the ferrite and martensite matrix, creating a surface nano-composite. Analysis using SEM and XRD revealed that the carbon and silicon-treated steel exhibited 41.4% martensite, 4.4% bainite, and 54.1% ferrite, indicating increased transformation by these elements. As a result, the alterations in the surface microstructure led to changes in the mechanical properties of the DP steel. Initially, the DP steel had Y.S. of 250 MPa and U.T.S. of 350 MPa. After SMAT treatment, its Y.S. and U.T.S. increased to 280 MPa and 380 MPa, respectively. The addition of carbon and silicon further enhanced the Y.S. and U.T.S. to 350 MPa and 450 MPa. A significant change in microhardness is achieved from 150HV0.05 to 255HV0.05 while after SMCT and SMCCT is 275HV0.05. Despite an increase in surface roughness contributing to heighten friction, there was a significant reduction in wear. This phenomenon could be attributed to grain refinement, dislocation structures, and martensite phase transformations associated with surface hardening.

Microstructure evolution of Incoloy 800H in industrial environment and correlation with creep mechanisms from literature

ABSTRACT The microstructures of 800 H samples affected by natural corrosion within industrial-like environmental conditions have been studied, and their potential effects on the creep response have been investigated based on literature information. Smooth cylindrical specimens of the alloy extracted from rolled sheet material have been placed into an industrial furnace, where they were exposed to high temperature thermal cycles within an air atmosphere. Samples spending 0 to 5 years inside the furnace underwent a microstructural characterisation campaign. Optical microscopy images reveal no grain coarsening. Macroscopic Vickers hardness shows a relatively wide surface hardness range (115≲HV10≲140). Compared to as-received material, micro-hardness profiles from specimens after years of high-temperature exposure exhibit a surface hardening trend within the vicinity of the edge exposed to the environment. Scanning electron microscopy analyses revealed two coexisting corrosion mechanisms: oxidation and nitridation. The latter is identified as the cause of the micro-indentation hardening trend.

Improving the Abrasion Resistance of Nodular Cast Iron Castings by Remelting Their Surfaces by Laser Beam.

This paper presents the results of research conducted in the field of the technology of surface hardening of castings from unalloyed and low-alloy nodular cast iron using the laser remelting method. The range of studies included macro- and microhardness measurements using Rockwell and Vickers methods as well as metallographic microscopic examinations using a scanning electron microscope. Moreover, abrasive wear resistance tests were performed using the pin-on-disk method in the friction pair of nodular cast iron-SiC abrasive paper and the reciprocating method in the friction pair of nodular cast iron-unalloyed steel. Analysis of the test results shows that the casting surface layer remelting by laser for unalloyed nodular cast iron results in a greater improvement in its resistance to abrasive wear in the metal-mineral system, as compared to low-alloy cast iron. Additionally, carrying out the laser hardening treatment of the surface layer made of the tested grades of nodular cast iron is justified only if the tribological system of the cooperating working parts and allowable dimensional changes during their operation are known.

Electron beam hardening of nanobainitic steel

Nanobainitic steels with high Si content are very promising materials due to the very favourable combination of mechanical and functional properties. However, sometimes in order to achieve the required results, it is necessary to further increase the surface's layer hardness. One of the feasible methods of surface hardening is electron beam hardening. In this work, 30 × 20 × 150 mm blocks made of nanobainitic steel were hardened using a defocused oscillating electron beam. Two methods of surface hardening were used – with movement of the sample relative to the heat source and hardening using only beam oscillation. The obtained samples were then subjected to light microscopic and scanning electron microscopic microstructure analysis as well as Vickers hardness testing. The average hardnesses of all hardened samples were in the range of 641–681 HV0.1 which means the surface hardening resulted in a hardness increase in the range of 239–279 HV0.1. The occurrence of similar hardening depths and hardness values in specimens hardened by both methods was an interesting phenomenon that was observed. The amount of energy input needed to achieve similar results was up to 35% less for the method without specimen movement.

РАССМОТРЕНИЕ УСТРОЙСТВ И СПОСОБОВ УПРОЧНЕНИЯ ГАЛТЕЛЕЙ ТЕЛ ВРАЩЕНИЯ ППД, ИХ КЛАССИФИКАЦИЯ И РАЗРАБОТКА РЕКОМЕНДАЦИЙ ПО СОВЕРШЕНСТВОВАНИЮ

The service life of heavily loaded shafts is largely determined by the degree of stress in the transition area from one diameter to another. There are a fairly large number of methods for reducing the stress concentration of these areas, but a special place in this case is occupied by strengthening the surfaces of non-profile, heavily loaded shafts. First of all, their fillets are subjected to hardening, which leads to the formation of uniformly distributed compressive stresses in the technological zone and, accordingly, an increase in the fatigue strength of such parts. The method has become especially widespread when hardening crankshafts. Along with this, surface hardening is applied to the abovementioned part to eliminate its bending. This technological process is especially important in the case of restoration of rotating parts. Meanwhile, existing work in this area does not solve existing issues. In this regard, it is necessary to give a critical analysis of the methods and designs for PPD fillets with the development of appropriate proposals, which determines the relevance of the work. The purpose of the study is to consider devices and methods for strengthening fillets of bodies of rotation of PPD, their classification and development of recommendations for improvement. To reveal the goal, the authors conducted a comprehensive review of the information available in the public domain regarding the strengthening of fillets by cold hardening. This made it possible to identify their advantages and disadvantages. First of all, this is the lack of a unified classification system, as well as methods for preventing the formation of a “wave of deformation”. Based on the analysis, a classification is proposed based on the factors that determine the properties of the shafts and the quality of their surface layers and the functional purpose of the processing. A proprietary scheme for processing SPD surfaces is proposed, which ensures the prevention of a “wave of deformation” in one pass of the working tool, which is based on the well-known principles of the theory of the introduction of a ball indenter into a solid.

Compatibility, Microstructure, and Mechanical Properties of a Dimethyl-Sulfoxide-Pretreated Graphene-Modified Asphalt Binder.

The surface of graphene was pretreated with dimethyl sulfoxide to enhance its dispersion in asphalt. To investigate the compatibility, microstructure, and mechanical properties of a dimethyl-sulfoxide-pretreated graphene (DG)-modified asphalt (DG asphalt). The interaction between asphalt and DG, DG dispersion, functional groups, tensile performance, microscopic structures, and micromechanical properties of the DG asphalt were characterized. Results indicate that DG with a particle size range from 0 to 8 μm is uniformly dispersed in asphalt. The irregular distribution of DG enhances the stress transfer distance, thus improving the energy consumption and mechanical properties of the DG asphalt. The preparation process involves physical blending, which reduces the saturated hydrocarbon content and increases the chemical bond energy, ultimately enhancing mechanical properties. Additionally, the surface of the DG asphalt shows numerous smaller sized bee structures, which contribute to the hardening and smoothness of the asphalt surface. The stress is distributed uniformly across the surface of the DG asphalt, minimizing stress concentrations. Furthermore, the light components in asphalt are adsorbed by DG, forming intercalated structures that decrease the adhesion and energy dissipation when compared to base asphalt. The compressive stress within bee structures consumes more energy and enhances the anti-deformation capacity of the DG asphalt. However, at higher deformation levels, the slipping of intercalated DG decreases its anti-deformation capacity when compared to that of base asphalt. Nonetheless, the interaction between intercalated structures prevents rapid tensile failure in the DG asphalt.

Anisotropic grain boundary diffusion process in textured sintered and hot-deformed Nd-Fe-B magnets

A systematic study of the dependence of the Grain Boundary Diffusion Process (GBDP) on texture using Dy and Dy-Nd-Cu in microcrystalline sintered and nanocrystalline hot deformed Nd-Fe-B magnets was performed. Diffusion parallel or perpendicular to the texture direction, the nominal c-axes orientation in the polycrystals, was investigated. By measuring thin slices from the respective samples, coercivity as a function of (i) magnet thickness and (ii) diffusion depth was obtained showing that GBDP efficiency depends on the diffusion direction, diffusion source as well as the grain morphology originating from the magnet production route. In nanocrystalline hot deformed magnets perpendicular diffusion is superior due to the platelet-like shape of the grains. Microcrystalline sintered magnets consist of equiaxed grains hence the main effects originate in anisotropic lattice diffusion and pole surface hardening. The magnetic properties are correlated with a comprehensive analysis of microstructure, chemistry and magnetization reversal.

Improved tribological behaviour of super duplex stainless steel through plasma nitriding at ultra-low temperature without prior polishing

Super duplex stainless steels (SDSS), widely used in industries such as offshore oil and gas, offer a unique combination of high strength and corrosion resistance. However, surface hardening treatments are crucial to enhance their performance and extend service life. This work investigates the effect of plasma nitriding on the tribological behaviour of SDSS SAF 2507. Samples are treated without prior polishing (as received, AR) at ultra-low temperatures (250 and 300 °C) aiming to avoid detrimental CrN precipitation. Comprehensive microstructural characterization, corrosion studies, and tribological tests (scratch and ball-on-disc) are conducted on samples that do not present CrN (PN). Results indicate that the hardness of PN samples nearly doubles that of AR samples due to the presence of expanded austenite. Corrosion tests show improvements in passivity for PN samples. In scratch tests, while the AR material undergoes progressive plastic deformation, in PN material the nitrided layer breaks down only after reaching a critical load. In ball-on-disc test, wear rates are remarkably lower for PN condition compared to AR condition. Wear mechanism is tribo-oxidative and abrasive for the AR condition. Wear of PN samples is characterized by asperity break-off and ratcheting. The nitrided layer in PN samples exhibits an enhanced load-bearing capacity that improves wear resistance in both tests.

The effect of laser shock peening with different power density on the microstructure evolution and mechanical properties of MAR-M247 nickel-base alloy

This study investigates the effects of laser shock peening (LSP) on the microstructural evolution and surface hardening of MAR-M247 nickel-based alloy. Experimental and numerical simulation methods are employed to analyze the influence of pulse power density and spot size. The results demonstrate that LSP significantly enhances surface hardness and yield strength. As the pulse power density increases, the magnitude and depth of plastic deformation increase. Higher power densities can implant deeper and greater compressive residual stress (CRS), but the corresponding tensile residual stress (TRS) also increases. Reducing both power density and spot size decreases the amount of plastic deformation of the surface. However, decreasing the spot size results in a decrease in the depth of the CRS. On the other side, based on the analysis of the microstructure, during the process of LSP, many dislocations accumulate in the γ matrix and evolve into subgrain boundaries, resulting in grain refinement. Additionally, LSP induces the precipitation of nanoscale carbides. This study tries to establish the influence law and action mechanism between LSP process-material property-microscopic evolution, which provides theoretical and applied data support for engineering applications.

Investigation of the Features of the Formation of Diffusion Layers During Nitrocementation of High-Chromium Steels in a Carbon Black Medium

The purpose of the work is to establish the regularities of the formation of the structure and phase composition of surface (modified) layers on 20X13 chromium stainless steel under intense saturation with carbon and nitrogen and, on this basis, to substantiate the possibility of surface hardening of parts made of high-chromium steels by nitrocementation.Methods. The studies were carried out on samples made of high–chromium steel 20X13, which were subjected to high-temperature nitrocementation in a paste-like medium including fine soot, sodium carbonate and potassium ferruginous oxide (paste-forming agent is an aqueous solution of carbomethylcellulose). The microstructure was studied using an optical metallographic microscope OLIMPUS OX 51 and a scanning electron microscope Qanta FEG-650 with an X-ray microanalysis system EDAX. The microhardness was determined on the Duramit-5 microhardometer, the phase composition on the XRD-7000S X-ray diffractometer.Results. Nitrocementation of high chromium steel 20X13 in the temperature range of 820–950°C provides the formation of diffusion layers on the surface, the structure of which is represented by three zones: a crust of solid carbonitrides on the surface, an eutectoid zone with a solid matrix and inclusions of carbonitrides under the crust and a transition zone including a solid solution enriched in carbon and nitrogen with grains of the base metal. The microhardness of the nitrocemented layers on 20X13 steel after quenching from 1050°C in oil and tempering at 600°C reaches Nm 750–800 on the surface and decreases smoothly enough in depth of the nitrocemented layer. The depth of nitrocemented layers with increased microhardness (more than 400 Nm), depending on the duration of treatment, can reach ~ 0.5 (860°C, 6 hours).Conclusion. Nitrocementation of high-chromium steel 20X13 at 820–880°C in an active carbon black paste with the addition of potassium ferrocarbon leads to an increase in the hardness of the surface layers by about 4 times the hardness of the base, which, combined with the high mechanical properties of the base, will significantly increase the service life of parts made of high-chromium stainless steels of type X13 operating under high contact conditions loads.

Continuous and Pulse TIG Arc Treatment for Surface Hardening of WAAM-MIG Parts

Continuous and Pulse TIG Arc Treatment for Surface Hardening of WAAM-MIG Parts

تأثير مدخلات الليزر Nd-YAG)) على الصلادة لصلب العدة عند درجات مختلفة من الخشونة السطحية

This research study focuses on the experimental analysis of surface hardening with laser rays for a sample of tool steel 1.2379 at different surface roughness's and laser parameters.The sample was received in an annealed condition with hardness value of 220 HV. The purpose of the experiment was to determine the effect of surface roughness and laser scanning speed on the surface hardness of the sample and the depth of the molten layer. The results showed that the surface roughness and laser scanning speed influenced the depth and hardness of the provided surface. It was observed that at slower scanning speed and a higher surface roughness, a higher hardness and a deeper cured layer thickness were achieved. A maximum surface hardness of 662 HV was achieved using a laser power of 75 W, a laser spot diameter of 0.5 mm, a pulse rate of 80 kHz, a laser processing speed of 1 mm/s, and at the higher surface roughness. Keywords: Tool Steel, Laser Surface Hardening, Surface Roughness, Microhardness, Scanning Speed.

Study on Fretting Wear Properties of GCr15 Steel Via Ultrasonic Surface Rolling Process

Abstract Ultrasonic surface rolling (USR) was applied to GCr15 steel with different static loads and passes to improve the friction and wear properties, and then the fretting wear mechanism of GCr15 steel after USR treatment was systematically investigated. The results showed that the specimens treated by the USR had lower surface roughness and significantly increased compressive residual stress and microhardness. Furthermore, severe plastic deformation occurred in the surface layer of the specimen, which refined the grains and increased the density of high- and low-angle grain boundaries. Besides, the results of the fretting test showed that the USR treated specimens had lower wear volume, dissipated energy, and steady-state friction coefficient. The fretting wear resistance increased with the static load and the number of passes. The fretting wear mechanism changed from abrasive wear and severe adhesive wear to slight fatigue wear and abrasive wear owing to the use of the USR treatment. Surface smoothing and hardening are responsible for the improvement in the fretting wear properties of GCr15 steel for USR treatment.

Comparison of Surface Hardening Processes Applied to AISI 5140 Steel withSide Load Test

AISI 5140 Tempered steel is generally preferred in the joints of vehicles. This steel is a material with high toughness. Its usage areas are quite wide. The purpose of the surface hardening process is to increase the wear resistance of surfaces exposed to wear, as well as to increase the fatigue life of the part and increase corrosion resistance. Since the inner parts of the parts are not affected by surface hardening, the resistance to impacts increases and therefore the formation of cracks on the surface is delayed. Surface hardening processes delay the formation of cracks on the surface and extend fatigue life. In this study, a comparison was made between a part with induction surface hardening, which is one of the methods in which the chemical composition of the surface is not changed, a part with nitration, which is one of the methods in which the chemical composition is not changed, and a part with standard reclamation heat treatment. Side Load test, a static testing method, was used for this comparison. In the Side Load test, the samples were compressed from the conical region and a vertical load was applied corresponding to the center of the joint. According to the results obtained in the tests, the sample with Induction surface hardening process withstood 64500 N, the sample with Nitriding heat treatment withstood 54500 N and the sample with Standard tempering heat treatment withstood 50200 N. According to the results obtained, the sample with the highest durability rate is the sample whose surface was hardened by induction.