Mechanical Properties Of Surface Layer Research Articles

Degree and depth of hardening under pendulum surface plastic deformation of carbon steel

The article discusses influence of the main technological parameters of pendulum surface plastic deformation (SPD) on the mechanical properties of surface layer of cylindrical parts made of carbon steel. Using the hardness tester HBRV-187.5 and the microhardness tester HMV-G21, we determined hardness of the surface layer, microhardness and depth of the work-hardened layer of hardened parts. In addition, the results of calculating the hardening degree are presented, which is important information for evaluating the effectiveness of SPD method in terms of improving the metal mechanical properties. Experimental studies showed that after pendulum SPD (at different processing modes), hardness of the surface layer increases by 9 – 12 % compared to hardness of the original surface, and the microhardness increases by 1.5 – 1.7 times, which leads to a significant hardening of the cylindrical billet surface layer. Depth of the hardened layer varies in the range of 0.9 – 1.1 mm, while the hardening degree is 45 – 65 %. Using the software package Statistica 10.1, which allows solving optimization problems based on statistical analysis and building an optimization model, we determined the optimal modes of hardening by pendulum SPD. These modes simultaneously provide both the maximum depth of the hardened layer and the highest hardening degree of the surface layer. They are formed under the following processing modes: radial interference t = 0.15 – 0.2 mm; longitudinal feed s = 0.07 – 0.11 mm/rev; billet rotation frequency nb = 160 – 200 min−1; frequency of the working tool pendulum movement nt = 110 – 130 strokes/min; angular amplitude of the working tool α = 35 – 40°. According to the results of experimental data and numerical calculations, it was established that the average grain size in pendulum SPD decreases by 30 – 40 % compared to the initial size, and the dislocation density increases by 2.5 times.

Micro- and nanohardness of GaTe single crystals

Gallium chalcogenide crystals draw attention of scientists due to their outstanding optical and optoelectric properties. The AIIIBVI crystals have a tendency to lamination due to van der Waals bonds, thus providing a possibility of making some nanometer thick plates parallel to a cleavage plane, and it broadens the scope of applications of these materials.In this regard, studying of mechanical properties is very important. However, substantial anisotropy of elastic and plastic properties restrains such investigations. Especially demanding is studying of mechanical properties of surface layers and correlation between them and mechanical properties of bulk crystals. In this work, the nanohardness HNI = 2.2 ± 0.2 GPa, and microhardness HV = 350 ± 35 MPa of GaTe crystals were measured on {201} cleavage plane. The elastic modulus of nanoindentation obtained from the deformation curve is ENI = 25 ± 0.5 GPa. Serrated deformation and its microstructural mechanism during nanoindentation are discussed. The fracture zone is studied.

Comparative Analysis of the Physical and Mechanical Properties of Surface Layers up to 200 nm of Cast Iron Grades A48-30B, 60-40-18

Comparative Analysis of the Physical and Mechanical Properties of Surface Layers up to 200 nm of Cast Iron Grades A48-30B, 60-40-18

Comparative Analysis of the Physical and Mechanical Properties of Surface Layers up to 200 nm of Cast Iron Grades A48-30B, 60-40-18

Comparative Analysis of the Physical and Mechanical Properties of Surface Layers up to 200 nm of Cast Iron Grades A48-30B, 60-40-18

Evolution of the Mechanical Properties of the Surface Layers of Aluminum Alloys under the Conditions of Sliding Friction

Mechanical properties of surface layers of aluminum alloys before and after friction tests are studied by nanoindentation. The influence of the composition of the alloys on these properties is analyzed. It is obtained that as a result of wear and tear, relatively compliant layer is formed on the surface of one of the alloys. Another sample demonstrates relatively rigid film at the surface of the friction path. Conclusions about different mechanisms of the wear and tear of alloys are made based on the analysis.

Research of Physical and Mechanical Properties of Surface Layers of Multilayer Ti/Al Films After Ion-Beam Mixing

Research of Physical and Mechanical Properties of Surface Layers of Multilayer Ti/Al Films After Ion-Beam Mixing

Structure and mechanical properties of surface layers of structural and tool steels formed by laser alloying with carbide-forming elements and boron

The research results of the process of laser alloying of structural and tool steels with different chemical elements are presented. Keywords: laser alloying, microstructure, hardness, diffusion, carbides, convective mixing, solid solutions. gavrilov1109@mail.ru

Nanoindentation tests titanium alloy Ti-6Al-4V after interference laser treatment

The study aimed was to assess selected mechanical properties of surface layers obtained after interference laser treatment – DLIL of titanium alloy Ti-6Al-4V used for implants. The samples were melted in still air at room temperature, for this purpose Nd:YAG laser was used, the number of laser shots was variable. Next, nanoindentation tests were performed, based on which Young’s modulus and nanohardness in the obtained surface layers were determined. An increase in nanohardness is observed in the surface layers after laser melting. An increase in the modulus of elasticity and higher hardness was observed for both the first and second areas on the sample surface. In the case of a sample for which three laser beam shots were used, hardness and Young’s modulus almost doubled. On the basis of the obtained results, it was found that the modified Ti-6Al-4V alloy can be used as an implant material, and the proposed method of modifying its surface may extend the life of such implants and improve their frictional properties.

Исследование структурных факторов, обеспечивающих повышение механических свойств поверхностных слоев, модифицированных импульсным электронно-пучковым облучением

Исследование структурных факторов, обеспечивающих повышение механических свойств поверхностных слоев, модифицированных импульсным электронно-пучковым облучением

Investigation of mechanical properties of hard finish turned and grinded surfaces

The main topic of the research conducted by the authors of this article is the study of the mechanical properties of surface layers after finish machining by two methods. The material of the test samples is 33NiCrMoV steel. The main aim of the authors is to compare hardness of the machined surface layers of this steel after hard finish turning and grinding. In the experimental process, quasi-static nanoindentation technique with the cube corner was used, and the microstructural analysis was performed by atomic force microscopy (AFM). Even before the start of the measurements that investigated the influence of hard finish turning technology against round grinding, it was necessary to subject the investigated 33NiCrMoV15 steel to basic research with regard to its chemical composition, fundamental microstructure and also microstructure of machined surfaces and basic mechanical and nano-mechanical properties. The microstructure was realized on the Oxford Instruments MFP-3D Infinity atomic force microscope AFM. All of these measurements were performed for investigating material properties using AF-FM viscoelastic mapping mode, which can register nanomechanical properties of materials. Chemical composition of investigated steel was performed on the spectral analyzer Spectrolab Jr CCD. Nano-mechanical properties, like nanohardness H and reduced Young modulus Er were subsequently performed on the Hysitron TI950 Triboindenter with a Cube Corner measuring tip, and then evaluated by the Triboscan software. Based on the acquired values, a 2D nanostructure of the distribution map of s H and Er was then evaluated in Matlab. This scientific research, together with all measured and calculated values, is the fundamental that will help to optimizing the quality and used all these results to optimize presented material and technological finishing processes in term of surface integrity.

The Effect of Implantation of Nitrogen Ions on Corrosion-Electrochemical and Other Properties of Armco-Iron. Part I. Preparation and Standardization of Specimens

The results of an investigation of the chemical composition, structure, topography, and mechanical properties of surface layers of armco-iron after implantation of nitrogen ions under various conditions are given. Using X-ray electron spectroscopy, the implanted nitrogen distribution profiles are determined and the formation of nonstoichiometric iron nitrides and oxynitrides is shown. Using X-ray analysis and electron energy-loss spectroscopy of dimensional fine structures, the atomic and local atomic structure of the ion-modified layers is studied.

The Contact Mechanics of Novikov’s Surface-Hardened Gearing during Running-in Process

The article is devoted to the analysis of the state of the contact surfaces of the higher kinematic pair in the general case of relative motion, that is, in the presence of rolling, sliding, and twisting, which is characteristic of Novikov’s circular-screw gears. The purpose of the work is to assess the impact of friction forces, the state of contact surfaces after tool processing, and the localization of the instantaneous contact spot on the level of contact—fatigue durability of gears. Power contact in the presence of geometric slippage of the mating surfaces leads to a significant change in the initial geometry and the mechanical properties of surface layers. In the existing methods of calculations of contact strength, the effect of running-in is investigated insufficiently, which leads to an incorrect result, especially for gear with high hardness of the teeth. In this work, the conditions of contact interaction close to the real requirements are studied on the basis of experimental material, numerical solution of the contact problem, determination of the terms of the contact areas of slip, and adhesion within the instantaneous spot. The shape of the instant contact spot has asymmetry and can be approximated by an ellipse with the introduction of a correction factor. The running-in period is of a plastic nature with cold deformation and reduction of the roughness of surfaces. As a result of the run-in period, the area of actual contact (tooth height) is increased by 2 or more times. It is not desirable to spread the area of contact at the area of adhesion that initiates the formation of pitting. The presence of defective surface area on the level of contact strength does not have significant influence, because of the running-in period, but increases the risk of spalling and brittle fracture.

Mechanical properties of surface layer of cutting elements from polycrystalline superhard composites based on cubic boron nitride

Предложено оценивать параметры механических свойств поверхностного слоя рабочих элементов из поликристаллических сверхтвердых композитов на основе кубического нитрида бора режущих инструмент по результатам анализа сканограмм, полученных методом склерометрирования. Представлено теоретическое обоснование метода и рассмотрены термодинамические показатели механических свойств поверхностного слоя – величину активационного барьера запуска процесса производства энтропии и способность к производству энтропии при приложении дозированного воздействия. Приведены результаты экспериментальных исследований работоспособности режущих инструментов из сверхтвердых композитов, полученные при точении закаленных сталей, подтверждающие теоретические выкладки.

Mechanical properties of surface layer of unfilled polypropylene

Using high doses of beta radiation for unfilled polypropylene (PP) and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The testing sapmles polypropylene (PP) were made by injection moulding technology and irradiated by high doses of beta radiation (0, 15 and 33 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using WAXS and instrumented ultra nano-hardness test. The results of the measurements showed considerable increase in micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation are used.

Formation of Hard Composite Layer on Tool Steel by Laser Alloying

Abstract Investigations include alloying the PMHSS6-5-3 steel surface layer with carbide and ceramic powders WC, VC, TiC, SiC, Si3N4 and Al2O3, using the high power diode laser (HPDL). Laser treatment is especially promising for solving contemporary surface engineering problems making it possible to focus precisely the delivered energy in the form of heat in the surface layer. The structural mechanism was determined of surface layers development, effect was studied of alloying parameters, method on structure refinement and influence of these factors on the mechanical properties of surface layer, and especially on its abrasive wear resistance. The fine grained martensite structure is responsible for hardness increase of the alloyed layer. The tribological wear relationships were determined for laser treated surface layers, determining friction coefficient, and wear trace shape developed due to the abrasive wear of the investigated surfaces. Comparison of the laser treatment parameters and tribological properties of surface layer after remelting and alloying with hard particles of the PMHSS6-5-3 steel using the high power diode laser to obtain the optimum service properties is the outcome of the investigations carried out.

Mechanical Properties of Surface Layers of Structural Steels After Nitriding and Possibilities of Adaptation of Their Nanostructure to Contact Deformation

The mechanism of plasticity of surface layers of structural steels after nitriding that yields nanosize particles with incoherent boundaries is considered with allowance for the possibility of adaptation diffusion processes initiated by friction strain.

Influence of Drill Wear to Local Plastic Deformation in the Wall of Drilling Hole

Final properties of plastic deformed parts of workpieces are affected by production technological processes. Therefore it is needful to know detailed structure changes of plastic deformed material caused by machining - grinding, drilling etc. Friction of tool to work surface caused one of three areas of plastic deformation in cutting zone. It has great influence to quality of work surface and local mechanical properties of surface layer of workpiece. Influence of drill wear to local plastic deformation in deformation zone around the surface of drilled holes was investigated. Two types of cutting tools were used: high speed steel drill IZAR HSSCO with diameter 6,0 mm surface hardened by boriding and the same one without boride layer. Standard cutting parameters were used. During the machining process, axial component of cutting force and torque were observed. The work piece was bulk from carbon steel Ck45 (1.0503). Wear of the tool was estimated as a wide of wear on tool flank. The local strain in analysed place of probes on their sections was obtained by stereological measurement of degree of grain boundaries orientation, which is proportional to grain boundaries deformation degree. Estimation of grain boundary orientation degree leads to determination of local plastic deformation in arbitrary place of workpiece. These results lead to detailed analysis of material structure changes caused by drilling from which local mechanical properties result.

Microstructure and mechanical properties of surface layer of M50NiL steel plasma nitrided

The quenched M50NiL steel specimens have been plasma nitrided at temperatures from 460 to 590°C for 4 h under a constant mixture gaseous supply of 0·05N2–0·4H2 L min−1. The effects of the treatment temperature on the microstructure, microhardness and wear resistance of the surface nitrided layers are studied. The results show that the plasma nitrided layer includes only the diffusion layer without conventional compound layer. The surface hardness is significantly enhanced. α′-Fe and γ′-Fe4N phases in surface layer are formed at relatively low nitriding temperatures (460–560°C), while a low nitrogen phase FeN0·076 forms when the nitriding temperature exceeds 575°C. With the increase in nitriding temperature, the nitrided layer thickness increases, whereas both the surface and core microhardness of the nitrided specimens decreases. The wear resistance of specimens can also be improved significantly by plasma nitriding.

Increase physical and mechanical properties of surface layers of steel laser and combined alloying

Представлено результати дослідження впливу зміни параметрів процесів лазерного та комбінованого лазерно-мікроплазмового легування на структуру поверхневих шарів та впливу структурних параметрів на зміну фізико-механічних властивостей одержаних легованих шарів. Використовуючи залежності металофізичних теорій управління структуроутворенням, виконано аналітичні оцінки характеристик тріщиностійкості, в’язкості руйнування та диференційованого внеску різних структурних факторів у зміну інтегрального значення границі текучості.

Formation of the composition and topography of surface layers of Cu50Ni50 foils under laser irradiation

The influence of the laser radiation power density on the changes in the composition and mechanical properties of surface layers of Cu50Ni50 foils has been investigated using X-ray photoelectron spectroscopy, scanning probe microscopy, X-ray diffraction, and microhardness measurements. It has been found that, after laser irradiation, the redistribution of elements occurs in the surface layer with a thickness of ∼30 nm on the irradiated side of the foil. It has been revealed that there are microdistortions in the crystal lattice of the alloy, microdeformations of grains, and variations in the microhardness of the irradiated surface. The mechanisms explaining the observed changes in the foils after laser irradiation have been proposed.