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A comparison of microstructure and mechanical properties of laser cladding and laser-induction hybrid cladding coatings on full-scale rail
摘要： With the rapid development of high-speed and heavy-haul trains, the surface damages of rails are becoming more and more severe, and how to promote the surface strength of the rail and prolong its service life with high efficiency are becoming extremely important. Laser cladding (LC), with small heat affected zone (HAZ) and low dilution, is a promising novel way to hardface and repair the rail. However, there are two great barriers for the traditional LC to apply on full-scale rails: one is how to prevent the coating from cracking under the rapid heating and cooling cycle; the other is how to eliminate the martensite structure in HAZ, which may threaten the safety of railway transportation due to its high hardness and low fracture toughness and usually be forbidden in almost all the Railway Standards over the world. In this paper, laser-induction hybrid cladding (LIHC) was innovatively proposed to deposit Ni-based coatings on a full-scale rail. The cracking behaviors, microstructures and mechanical properties of the coatings and HAZs by LC, LIHC with induction pre-heating (pre-LIHC) and LIHC with induction post-heating (post-LIHC) were studied systemically. The results indicate that the cracking and martensite transformation occurred in the HAZ can only be prevented by post-LIHC, where fine pearlite with smaller pearlite block size and lower interlamellar spacing formed instead. Therefore, the abrupt change of microstructure and mechanical properties in the HAZ could be avoided by post-LIHC, and the hardness, strength and toughness of the rails can be improved significantly. The post-LIHC technology shows the potentiality to hardface and repair the full-scale rail.
关键词： Martensite,Microhardness distribution,Toughness,Laser-induction hybrid cladding (LIHC),Full-scale rail,Strength
更新于2025-11-28 14:24:20
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A study of metallurgy and erosion in laser surface alloying of AlxCu0.5FeNiTi high entropy alloy
摘要： AlxCu0.5FeNiTi high entropy alloy coating is synthesized by premixed high purity Cu, Fe, Ni and Ti powders on AA1050 aluminium substrate by laser surface alloying, with the aim to improve microhardness and erosion rate. Phase constituents, microstructure and microhardness were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vickers Microhardness tester, respectively. The erosion behavior of AlxCu0.5FeNiTi coating is checked using an air jet erosion setup. SEM images show presence of three regions. Percentage compositions of these regions are evaluated using Energy Dispersive Spectroscopy. XRD analysis of AlxCu0.5FeNiTi coating confirmed that these regions are a mixture of disordered BCC and two FCC solid solution phases. The microhardness of the AlxCu0.5FeNiTi HEA is 18 times that of the AA1050 aluminium substrate. Results show that AlxCu0.5FeNiTi HEA coating has improved erosion resistance.
关键词： Laser Surface Alloying,Microhardness,Microstructure,High Entropy Alloy,Erosion rate
更新于2025-11-21 11:18:25
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Effects of three-dimensional vibration on laser cladding of SS316L alloy
摘要： As a widely used approach for surface modi?cation, laser cladding plays a signi?cant role in surface hardening and repairing of metallic parts. However, the defects existing in laser cladding parts, such as cracks, tensile residual stress, and pores, signi?cantly a?ect the performance and the application of the cladding parts. In this study, an SS316L layer was fabricated on a 45 steel substrate using a laser cladding process assisted by three-dimensional vibration. The microstructures and the properties of the coating and the bonding interface with various vibration parameters were analyzed and compared. The microstructures of the cladding layer and the matrix were analyzed by an optical microscope and a scanning electron microscope. The results show that the three-dimensional vibration is able to re?ne the columnar dendrites in the cladding layer. The oscillation accelerates both the liquid ?ow and the thermal transfer of the molten pool, which not only reduces the temperature gradient but also increases the solidi?cation growth rate. Meanwhile, the porosity and the maximum pore size in the cladding layer were signi?cantly reduced by the vibration. The average microhardness of the cladding layer signi?cantly increased assisted by the three-dimensional vibration. Experimental results demonstrate that the e?ects of the three-dimensional vibration are more signi?cant than the single vertical vibration. The proposed approach provides a potential way to improve laser additive manufacturing and remanufacturing.
关键词： laser cladding,microhardness,three-dimensional vibration,microstructure
更新于2025-11-21 11:18:25
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AIP Conference Proceedings [Author(s) ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2016: Proceedings of the International Conference on Advanced Materials with Hierarchical Structure for New Technologies and Reliable Structures 2016 - Tomsk, Russia (19–23 September 2016)] - Protection from high-velocity impact particles for quartz glass by coatings on the basis of Al-Si-N
摘要： The paper presents the results of the research of the phase composition and the mechanical properties of the coatings on the basis of Al-Si-N system produced by pulsed magnetron sputtering on the KV glass substrates. By the X-ray diffraction method, it has been discovered that the coatings contain AlN phase (hcp) with different thickness. The deposition of Al-Si-N coating system allows both increasing the microhardness of the surface layer of the quartz glass up to 29 GPa, and maintaining high elastic properties (We > 0.70). The laboratory tests have been carried out involving the impact of high-speed flows of iron particles on the Al-Si-N protective coating with different thicknesses produced by pulsed magnetron sputtering. The increase of Al-Si-N coating thickness from 1μm to 10μm decreases 4-fold the surface density of the craters on the samples caused by a high-speed flow of iron particles.
关键词： structure-phase state,microhardness,crater density,optical properties,protective coating,magnetron deposition
更新于2025-09-23 15:22:29
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Does the Photon-Induced Photoacoustic Streaming Activation of Irrigation Solutions Alter the Dentin Microhardness?
摘要： Objective: The aim of this in vitro study was to evaluate the efficacy of photon-induced photoacoustic streaming (PIPS) activation of sodium hypochlorite (NaOCl), chlorhexidine (CHX) or ethylenediaminetetraacetic acid (EDTA) on the dentin microhardness and to assess the compositional changes of root dentin. Background data: It is still unclear whether PIPS activation of irrigants alters the dentin microhardness and mineral content of dentin. Materials and methods: Root canals of 72 extracted single-rooted teeth were prepared and teeth were fixed in microcentrifuge tubes with silicone impression material. After setting of the silicone, teeth were removed and split longitudinally in buccolingual direction. One half was used as control (pretreatment) while the other was placed into the tube (posttreatment). Then specimens were divided into six test groups (three with and three without PIPS activation). The irrigants tested were 2.5% NaOCl, 17% EDTA, and 2% CHX. Experimental tooth specimens were irrigated with 6 mL of test solution, with additional PIPS activation applied to the PIPS groups. Then specimens were subjected to Vickers microhardness testing. Percentage change of microhardness was calculated. Energy dispersive X-ray spectroscopy (SEM-EDX) was performed to measure element content. Results: Among the irrigant-alone groups, NaOCl and CHX did not alter the dentin microhardness, whereas statistically lower microhardness values were obtained in EDTA group. Chemical composition of dentin was affected from all irrigants used. PIPS activation led to no additional alteration in dentin microhardness. PIPS significantly increased the phosphorus level in NaOCl group. Conclusions: Dentin microhardness was significantly affected by the irrigation solution, not by the PIPS activation.
关键词： irrigants,PIPS,photoacoustic streaming,dentin microhardness,mineral content
更新于2025-09-23 15:22:29
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Selected properties of laser cladding coatings shaped using Flow drill technology
摘要： The paper presents the investigations of selected chemical and mechanical properties as well as macro- and microstructure of materials formed using thermal drilling process (Flow drill). The aim of this study was to determine the microstructure of the coatings produced using laser cladding with powder technology. The coatings were produced on the low-carbon steel using 1 kW disc laser. After modification of surface, the thermal drilling process was applied. To produce all coatings, the pure copper powder was used. In this study the laser power equal of 500, 700 and 900 W were used. The microstructure, chemical composition (EDS) and microhardness were investigation. It was found that the surface modification of low carbon steel and next conducted thermal drilling process caused change the surface properties on the hole flange. It was found that surface modification of steel using laser cladding with cooper powder and next Flow drill process contributes to the change in microhardness and chemical composition on hole flange.
关键词： microhardness,microstructure,laser cladding,chemical composition,Flow drill technology
更新于2025-09-23 15:21:21
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Comparative Study on Microstructure and Aluminum Distribution Between Laser Beam Welding and Electron Beam Welding of Tia??6Ala??4V Alloy Plates
摘要： Ti–6Al–4V alloy plates with a thickness of 4 mm were joined by electron beam welding (EBW) and laser beam welding (LBW). The comparison of LBW and EBW was performed according to grain morphology, microstructure, aluminum distribution, and microhardness of the joints. Results indicate that compared with LBW joint, more equiaxed grains are observed around the central zone of the EBW joint. The microstructure in fusion zone (FZ) of EBW joint presents more uneven with obviously coarser acicular martensite α′. Moreover, the aluminum element content of EBW joint is substantially lower, which demonstrates a more significant burning loss behavior in EBW process. The lower aluminum content in the upper center areas of the joints is attributed to the more significant element burning loss caused by higher temperature, whereas more uniform aluminum distribution in the upper part of the joints is ascribed to stronger convection form within the upper part of the joint. In addition, the characteristics of convection and thermal field within the molten pool are recognized as vital factors influencing the aluminum distribution. The lower microhardness profile in FZ of the EBW joint is principally attributed to coarser acicular martensite α′ and lower aluminum element in EBW joint.
关键词： Electron beam welding,Microhardness,Microstructure,Burning loss,Titanium alloy,Laser beam welding
更新于2025-09-23 15:21:01
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Influence of Focused Pulsed Laser Radiation on the Properties of Amorphous FeSi6B16 Metal Alloy
摘要： The effect of focused pulsed laser radiation (number of pulses and power density) on an amorphous FeSi6B16 metal film is studied. The states of the alloy before and after laser irradiation are analyzed using methods of atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and microhardness measurements. Focused laser radiation in any exposure mode is established to cause high-temperature heating of the surface of an amorphous alloy in the irradiation zone. The result of such heating is melting of the material surface and propagation of the heat wave front from the strongly heated surface to its inner layers, which induces the redistribution of elements in the Fe–Si–B system, a change in the structure, and an increase in the microhardness.
关键词： microhardness,nonequilibrium state,X-ray photoelectron spectroscopy,atomic-force microscopy,surface,laser radiation,amorphous alloys
更新于2025-09-23 15:21:01
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Effect of laser surface melting on surface integrity of Ala??4.5Cu composites reinforced with SiC and MoS2
摘要： Two types of composites were prepared with Al?4.5Cu alloy as a matrix using stir casting method. One was reinforced with 10 wt.% of SiC and 2 wt.% of MoS2. The other was reinforced with 10 wt.% of SiC and 4 wt.% of MoS2. Their surfaces were remelted using a CO2 laser beam with an objective to study the influence of laser surface melting (LSM). The topography, microhardness, corrosion resistance and wear resistance of the laser melted surfaces were studied. Overall surface integrity after LSM was compared with as-cast surface. LSM enhanced the microhardness and wear resistance of the surface in each case. Porosity of the laser melted surface was low and corrosion resistance was high. Thus, LSM can be conveniently applied to enhancing the surface integrity of the aluminium composites. However, there is an optimum laser specific energy, around 38 J/m2 in this study, for obtaining the best surface integrity.
关键词： microhardness,aluminium composites,laser surface melting,corrosion resistance,molybdenum disulfide,silicon carbide
更新于2025-09-23 15:21:01
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Comparative analysis of pulsed Nd:YAG laser welding of 304L and 904L stainless steel
摘要： The current study investigates the comparative study of similar pulsed Nd:YAG laser welding of 304L and 904L stainless steel. In the present study both austenitic stainless steel (304L) and super austenitic stainless steel (904L) are laser welded at 5 mm/s scanning speed, 25 Hz pulse frequency and 0.75 mm laser spot diameter. The ultimate tensile strength of both laser welded specimens were equal to the respective parent metals. The percent of ductility is more in 304L than 904L laser welded specimen comparatively. The weld bead shape of the two welded specimens are V shaped for 304L and H shaped for 904L at the same laser process parameters due to difference in thermophysical properties of the two materials.
关键词： 904L,Pulsed Nd:YAG,Microhardness,304L,Microstructure,Laser welding
更新于2025-09-23 15:21:01