Microstructure Of Metal Research Articles

Achieving strong interfacial bonding of CFRP and magnesium alloy by modifying magnesium alloy surface via alkaline etching with EDTA addition

The interfacial properties of fibre metal laminates are closely related to the surface microstructure of metals. Herein, a hitherto unreported honeycomb-like micro/nano-porous structure was successfully fabricated on an AZ31B Mg alloy surface by incorporation of ethylenediaminetetraacetic acid disodium (EDTA-2Na) into an alkaline solution and achieved excellent interfacial bonding property between AZ31B and carbon fibre-reinforced plastic. The addition of EDTA-2Na can promote the formation of etched pores. The growing nano-scale etched pores join together to produce micro-scale pores and ultimately lead to the formation of a micro/nano-porous structure. The 60 min etched AZ31B/carbon fibre-reinforced plastic laminate exhibits a bonding strength of 25.87 MPa, which is an increase of 350.7% compared to that of the untreated sample. The significant increase in bonding strength is mostly ascribed to composite mechanical interlocking by the micro/nano-porous structure and chemical bonding through the formation of MgCO3 and MgO1+X. In addition, the characteristics of micro-pores also affect the bonding strength.

Impact of various heat treatment processes and welding speeds on the mechanical properties and microstructures of soft/hard composite joints

There is a certain contradiction between the formability and strength of auto parts. In this work, the whole-process processing technology of hot stamping soft steel was designed, and 500 MPa grade mild steel (500HS) with uniform microstructure was prepared. To take into account the strength and formability of hot stamping soft steel, here, based on laser welding technology, 500 MPa grade soft steel, and 1500 MPa grade hard steel are benignly composited, and by adjusting the laser welding speed and heat treatment process, the loss of mechanical properties caused by the weld seam is eliminated. A soft/hard composite steel for automobiles with excellent strength, ductility and formability is obtained. To maintain excellent deformation resistance and bonding force of the weld, the heat-affected zone of 500HS retains part of bainite and pearlite, which is beneficial to the strain compatibility and stress partitioning with the microstructure of the base metal, and the hardness is low. After heat treatment, which helps to transfer the stress concentration effect to the 500HS base metal with strong energy absorption capacity, so that the clad steel has excellent comprehensive mechanical properties. This process is developed based on existing industrialized equipment and has broad application prospects.

Effect of Tool Geometry on the Microstructure of Friction Stir Welding of Copper and 316L Stainless Steel

The microstructure evolution during dissimilar friction stir welding of copper with stainless steel 316L is studied. The welding is performed in transparence configuration using tools of two different geometries. The joints are characterized by optical microscopy, scanning and transmission electron microscopy, electron backscattered diffraction, and microhardness. The microstructure and crystallographic texture of base metals are significantly affected. The joint produced using a shoulder of 8 mm in diameter is characterized by a copper nugget with refined grains. The texture of copper is dominated by component of the shear texture. The steel beneath the tool shows a grain refinement with grains of sub‐micron size and a texture which is close to the ideal simple shear texture. For the joint produced by the 16 mm diameter tool shoulder, the nugget consists of large grains of copper, while the steel beneath the tool shows small recrystallized grains of micrometer size. The texture in the steel is dominated by the component of the shear texture. The Cu/316L interface in both types of joint is of very good quality. In a detailed study of the interface, it is revealed that the welding of metals is achieved by mutual intense mechanical interlocking without formation of any intermetallic compounds.

Influence of Heat Input on Microstructure and Mechanical Properties of Laser Weld Metal in 2507 Duplex Stainless Steel by Different Welding Speed and Welding Power

This manuscript attempts to explore the macroscopic morphology microstructural aspects and mechanical properties of different laser welding speed and power on the 2.5 mm thick DSS welding joint. Through the evaluation of 12 groups samples with different welding parameters, we found that the optimal laser welding process parameters were a welding speed of 6mm/s, laser power of 1.6 kW and welding speed of 8 mm/s, laser power of 1.7 kW. When the heat input was 2.125 kJ/cm, the content of ferrite and austenite was relatively uniform, and the ratio was close to 1:1. We found that the hardness of the weld metal zone was slightly higher than that of the base metal, with an average value of 330 HV. When the heat input was 2.125 kJ/cm, the microhardness of welded joint was better than other parameters, reaching 400 HV in the welding metal zone. The tensile strength of the weld was enhanced with the increase of heat input, and the maximum was 900 MPa. Through SEM analysis, the fracture locations of tensile specimens were all in the weld zone, and the fracture morphology had a large number of dimples, belonging to the ductile fracture.

Site-controlled preparation of metallic microstructures via mechanical scratch-induced selective electrodeposition

Controlled preparation of metallic microstructures attracts wide interest in sensor and electronic fields. However, limited by fabrication technology, it faces challenges in achieving template-free and orientational formation of metallic microstructures. Herein, a site-controlled strategy via scratch-induced selective electrodeposition was proposed to prepare high-quality metallic structures on silicon (Si) surface with the assistance of scanning probe lithography (SPL). The effects of scratching and depositing conditions were systematically investigated for optimizing the preparation process. Selective electrodeposition mechanisms were addressed through topographic and conductive detections. It was found that single-cycle scratch created under higher loads was beneficial for preparing compact and continuous Cu structures. Further analysis indicated that higher normal loads in scratching can facilitate obtaining more conductive sites, promoting orientated migration of metal ions during the reaction, while the increase of reciprocating cycles can cause more amorphous layers and hinder electron transport. Moreover, post-annealing treatment can lead to the growth of Cu grain sizes, which contributes to the crystallinity. Notably, the proposed method is demonstrated with the preparation of Cu coils, which is sensitive to alternating magnetic field. These findings shed new light on the site-controlled preparation of high-quality metallic microstructures and the applications.

Tesla-class single-cycle terahertz magnetic field pulses generated with a spiral-shaped metal microstructure

Abstract We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with near-infrared light. The determined magnetic field strength and field-enhancement spectrum are consistent with the theoretical predictions. This first report of the detection of the magnetic field of a Tesla-class picosecond pulse by magneto-optical sampling is expected to be useful in research on the control of magnetization in spintronic devices.

Simultaneously enhancing strength and fracture toughness via tailoring the microstructure in X80 girth weld metal

Brittle fracture of girth weld metal is the main failure form of high strength steel oil and gas pipeline facilities, which is related to the deterioration of mechanical properties of weld metal at low temperature, especially the fracture toughness. In order to improve the strength and fracture toughness, tempering and intercritical quenching-tempering treatment are used in X80 girth weld metal. The results demonstrate that the heat treatment processes not only decomposed M-A constituent, but also increased grain size, reduced dislocation density and increased precipitated phase content. In the intercritical quenching-tempering treatment, small size retained austenite was produced, which was rich in carbon and manganese elements. The tempering and intercritical quenching-tempering treatment process significantly improved the tensile properties and fracture toughness, so that the Rt0.5 increased from 598 MPa to 629 MPa and 648 MPa, and the value of crack tip opening displacement (CTOD) increased from 0.05 mm to 0.12 mm and 0.23 mm, respectively. (Nb,Ti)C precipitated during heat treatment could effectively improve the yield strength, and the increase of precipitation strengthening is much higher than the strength loss caused by grain size increase and dislocation density reduction. Transformation induced plasticity effect of stable retained austenite formed by intercritical quenching-tempering treatment could effectively inhibit crack propagation and improve fracture toughness. The combined effect of retained austenite and nano-precipitated (Nb,Ti)C significantly improves the strength and fracture toughness of the weld metal. Generally, the research results have important scientific value and engineering significance for explaining the strength and toughness mechanism of girth weld and practical pipeline engineering application.

Metal flowing and microstructure characteristics of the micro inner gear ring fabricated by rheological extrusion

Metal flowing and microstructure characteristics of the micro inner gear ring fabricated by rheological extrusion

Effects of post-weld heat treatment on the microstructure and properties of the matching SMAW filler metal for weld joints in MarBN steel

AbstractA detailed investigation has been carried out of the matching composition filler metal for welding MarBN steel to explore the influence of welding procedure and post-weld heat treatment (PWHT) on the microstructure and properties of the weld metal and a MarBN steel weld joint. The filler metal was in the form of a shielded metal arc welding (SMAW) electrode. With different interpass temperatures and PWHT procedures applied, the microstructure and mechanical properties, particularly toughness, of the all-weld metal deposits and welded MarBN alloy joints were examined. The differences in microstructure (grain structure, precipitates, etc.) were evaluated to provide a better understanding of how the PWHTs influence the starting conditions of the matching weld metal and welded MarBN steel joints before service. The current work found that for a 30-mm-thick all-weld metal coupon, reasonable impact toughness was achieved after PWHT of 735 °C × 8 h; longer heat treatment durations (16 h and 36 h) did not further increase the toughness. For thicker cast blocks, a PWHT of 735 °C × 16 h was needed for weld toughness comparable to the base metal, hence was considered more appropriate for actual engineering applications. Evenly distributed Laves phase precipitation was observed after 735 °C × 8 h; the precipitates gradually increased in size and area fraction as the duration increased, and appeared to be stable when approaching 36 h. Differences in the precipitation were observed between different weld regions. The weld cap region had a lower density of Laves precipitates compared to the lower weld area. From the current investigation, aspects for further investigation are also identified.

Femtosecond Laser Combined with Hydrothermal Method to Construct Three-Dimensional Spatially Distributed Wurtzite ZnO Micro/Nanostructures to Enhance Photocatalytic Properties.

Conventional approaches employing nanopowder particles or deposition photocatalytic nanofilm materials encounter challenges such as performance instability, susceptibility to detachment, and recycling complications in practical photocatalytic scenarios. In this study, a novel fabrication strategy is proposed that uses femtosecond laser direct writing of self-sourced metal to prepare a self-supporting microstructure substrate and combines the hydrothermal method to construct a three-dimensional spatially distributed metal oxide micro/nanostructure. The obtained wurtzite ZnO micro/nanostructure has excellent wetting properties while obtaining a larger specific surface area and can achieve effective adsorption of methyl orange molecules. Moreover, the tight integration of ZnO with the surface interface of the self-sourced metal microstructure substrate will facilitate efficient charge transfer. Simultaneously, it improves the efficiency of light utilization (absorption) and the number of active sites in the photocatalytic process, ultimately leading to excellent photodegradation stability. This result provides an innovative technology solution for achieving efficient semiconductor surface-interface photocatalytic performance and stability.

Effect of heat treatment on the microstructure and mechanical properties of yttrium metal

Effect of heat treatment on the microstructure and mechanical properties of yttrium metal

High-Precise Metallic Helical Microstructure Fabrication by Rotational Nanorobotic Manipulation System With Tilted Mandrel Compensation

High-Precise Metallic Helical Microstructure Fabrication by Rotational Nanorobotic Manipulation System With Tilted Mandrel Compensation

The Obtaining of Regular Metal and Dielectric Microstructures Based on Irradiation–Modified Polymer Films

The Obtaining of Regular Metal and Dielectric Microstructures Based on Irradiation–Modified Polymer Films

Effects of Welding Techniques on the Corrosion Resistance of Mild Steel

The performance and longevity of welded structures depend heavily on corrosion resistance, particularly when mild steel is used as the primary material. The paper provides an overview of the investigation of the influence of various welding techniques on the corrosion resistance of mild steel. The study combines mild steel specimens using spot-welding, gas metal arc, and electric arc welding techniques. Electrochemical and immersion testing techniques are used to assess the welded samples' resistance to corrosion. The impact of metal microstructure, welded zone surface characteristics, corrosion rates, and filler material selection on corrosion resistance is examined. The results demonstrate that the choice of welding process has a significant effect on mild steel corrosion resistance. Some techniques have a higher level of corrosion resistance owing to the use of heat. As exposure duration rises, both diluted and concentrated hydrochloric acids cause weight loss in the absence of an inhibitor. The temperature increased over time until 190 minutes, which resulted in a decrease in temperature efficiency. In the impact test, adding 3%, 6%, and 9% of the welded components to the metal alloy increased the impact's energy output from 12.32 J to 12.69 J, 12.99 J, and 13.51 J, respectively. The energy effect of the reinforced mild steel was reduced owing to the brittleness of the welded parts relative to the ductile metal matrix. The composite absorbs impact stresses, and the enhanced weight ratio of the welded mild steel thereby increases its toughness.

Microstructural and mechanical properties of electron beam welded super duplex stainless steel

The electron beam welding of super duplex stainless steels is associated with challenges due to the concentrated heat input and the nitrogen loss that result in a predominantly ferritic structure after the solidification. This study presents an approach to overcome this issue by feeding nickel-based filler wire into the melt pool in welding of 2507 super duplex stainless steel. Results showed that the high-frequency beam oscillation combined with a multi-beam technique led a good mixing between the base metal and the filler wire, even at a large depth-to-width ratio. Additionally, the weld geometry was characterized by near-parallel fusion lines and a narrow heat-affected zone. The nickel addition resulted in a balanced microstructure in the weld metal with ferrite fractions of 35–55 %, despite a significant nitrogen loss, consequently leading to impact energy values of 215 ± 15 J and hardness values of 285 ± 15 HV. The findings of this investigation allow fabricators to effectively design electron beam welding processes for producing thick-walled super duplex stainless steel components.

Improving Commercial Motor Bike Rim Disc Hardness Using a Continuous-Wave Infrared Fibre Laser

This study is focused on examining the feasibility of applying laser hardening to a commercial metallic bike rim, employing a CW IR fibre laser. The research comprises two main phases. The first phase involves an assessment of the impact of laser parameters on the metallic microstructure, while the second phase involves the actual laser hardening of the bike rim. A comprehensive evaluation encompassing hardness measurements, optical microscopy, and scanning electron microscopy was conducted on the samples. The microstructure type can be manipulated by skilfully adjusting the laser parameters, allowing for the creation of various microstructure variants within the laser-hardened zone for specific laser conditions. In this regard, multiple microstructure types were observed. The hardness of the laser-processed zones exhibited variations corresponding to the specific microstructure. Notably, the molten zone (MZ) and the second heat-affected zone (HAZ II) exhibited the highest levels of hardness. Furthermore, it was observed that a scan overlap of ≥ 75% led to an augmentation in hardness. This study sheds light on the intricate interplay between laser parameters, microstructure, and resultant hardness in the context of laser hardening of metallic materials.

Elliptical vibration chiseling: a novel process for texturing ultra-high-aspect-ratio microstructures on the metallic surface

Highlights Elliptical vibration chiseling is proposed based on a game-changing process principle for the high-efficient texturing of ultrahigh-aspect-ratio surface microstructures. Uniformed microstructures with an aspect ratio of 2–12 in the spacing scale of 1–10 μm have been successfully fabricated using elliptical vibration chiseling. The developed process model of elliptical vibration chiseling has been verified by the measured results of the microstructures’ geometric parameters. An inclined elliptical trajectory of tool vibration is more suitable for elliptical vibration chiseling than the standard elliptical trajectory. The deterministic process effects on the surface generation of microstructure in elliptical vibration chiseling have been demonstrated.

A continuum scale chemo-mechanical model for multi-trap hydrogen transport in deformed polycrystalline metals

This study presents a coupled multi-trap hydrogen diffusion and crystal plasticity model within a thermodynamically consistent framework. The developed modeling scheme incorporates the hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced strain-induced plasticity (HESIV) based on thermodynamic considerations. The theoretical formulations are implemented in the finite element method, which considers the concentration- and chemical potential-based balance equations. The validity of the coupled model is established through preliminary single element simulations under isothermal conditions, showcasing the predictability of evolution of hydrogen concentration and occupancies in the deformed microstructure of polycrystalline metal. Then, the developed computational approach is applied to two materials exhibiting hydrogen-induced hardening and softening behaviors in accordance with the HELP mechanism and vacancy-hydrogen complex (VaH) formation under isothermal condition. The model successfully reproduces the change of mechanical behavior induced by hydrogen in both materials. The effects of hydrogen diffusivity and the binding energy of defects on hydrogen transport are also investigated. Furthermore, the sensitivity of hydrogen diffusion to different trapping mechanisms, local equilibrium trapping and kinetics trapping, is examined. The proposed modeling framework can be applied to new material design strategies for developing metals resistant to hydrogen embrittlement.

Sinking ECDM micro-milling of micro-channels with a customized electrode

ABSTRACT Electrochemical discharge machining (ECDM) micro-milling exhibits enormous machining potential in manufacturing metal microstructures. In this paper, a novel sinking ECDM micro-milling using glycol-based electrolyte is proposed for the high-quality fabrication of metal micro-channel structures. Firstly, a novel combined process is developed for the simple and efficient preparation of micro-electrode. With the proposed method, a micro-electrode with 91.1 μm in diameter and 21.2:1 in aspect ratio is successfully machined in 47.2 minutes. Secondly, experimental research on ECDM micro-milling machining of micro-channels in glycol-based electrolyte is carried out using the fabricated micro-electrode. Experimental results show that the machined voltage significantly affects the machining quality of micro-channels. Wear analysis reveals that the bottom geometry of the micro-electrode exhibits equal wear along the axis direction with processing times increasing, and a constant length compensation strategy (1.52 μm/mm) is adopted. Finally, an S-shaped micro-channel without recast layers (Ra 0.093 μm) was successfully fabricated.

Microstructure – Properties relationship in laser-welded AZ31B magnesium alloy

The AZ31B magnesium alloy was laser-welded at three different (1.2, 1.6, and 2 kW) laser output powers in the present work. All the butt weld joints are almost defect-free. The size of the weld joint slightly increases with increasing laser output power. The weld metal is formed by columnar grains of the alpha phase at the weld metal/base metal interface, but a finely equiaxed grain microstructure is formed in the centres of fusion zones. The minor phases are Mg17Al12 and (Al,Mg)8Mn5. The weld metal microstructure manifests clear refinement with a decrease in laser output power. Microstructural changes are reflected in changes in mechanical properties; weld joints prepared at the lowest laser output power manifest the highest microhardness, ultimate tensile strength, yield strength, and almost 90% joint efficiency. This is related to the different extents of strengthening mechanisms that act most effectively in weld joints made at 1.2 kW laser output power. Detail analysis of fracture surfaces confirmed that lower laser output power and general microstructural refinement favours the formation of plastically deformed material, which is in excellent agreement with both the experimentally determined and the calculated values of yield strength.