Transverse Grain Research Articles

Effect of Bamboo Nodes on the Mechanical Properties of Phyllostachys iridescens

Bamboo is a significant natural resource, recognized for its rapid growth, lightweight composition, high strength, and excellent mechanical properties, making it increasingly valuable in the furniture and construction industries. A critical structural aspect of bamboo is its nodes, yet there has been limited research on their impact on bamboo’s mechanical properties. This study investigates the mechanical properties of round bamboo tubes in three different states: internodes (S1), nodes with diaphragm removed (S2), and nodes with diaphragm (S3). The results show that the mechanical properties of S1 are a compressive strength (CS) of 29.72 MPa, a shear strength parallel to grain (SSp) of 11.82 MPa, a radial stiffness (Sr) of 155.59 MPa, an impact toughness (IT) of 20.74 kJ/m2, a modulus of rupture (MOR) of 16.45 MPa, a modulus of elasticity (MOE) of 408.53 MPa, a tensile modulus of rupture parallel to grain (MORT) of 189.62 MPa, and a tensile modulus of elasticity parallel to grain (MOET) of 431.05 MPa. Compared with S1, these above parameters change by CS +11%, SSp 6%, Sr +100%, IT −29%, MOR +5%, MOE +63%, MORT −29%, and MOET −58% in S2 and CS +10%, SSp 28%, Sr +250%, IT −31%, MOR +28%, MOE +92%, MORT −25%, and MOET −42% in S3. It demonstrates that the bamboo diaphragm and nodes significantly influence the mechanical properties of bamboo; they have a significant positive effect on the bending properties across the transverse grain, radial ring stiffness, and shear properties along the grain, but negatively impact the tensile properties along the grain.

Multi-scale microstructure and its synergetic strengthening effect in stress rupture life of Inconel 718 fabricated by high-deposition-rate laser directed energy deposition

Superior elevated temperature properties are critical for the application of Inconel 718 in hot-end components. The utilization of high-deposition-rate laser directed energy deposition (HDR-LDED) increases the microstructural diversity of Inconel 718, which accordingly provides more opportunities for properties improvement. Herein, Inconel 718 alloy with a multi-scale microstructure were fabricated by HDR-LDED followed by customized heat treatment. The coarser columnar grains (width ∼300 μm) were obtained with γ" phase (diameter ∼33.74 nm and volume fraction ∼15.16 %) distributed homogeneously in the grain and the fine Laves phases (length ∼3.69 μm; width ∼1.94 μm; aspect ratio ∼1.99 and volume fraction ∼1.55 %) in the inter-dendritic region. This multi-scale microstructure possesses an excellent stress rupture life of 342.9 h with the elongation of 13 % at 650 °C, which far exceeds that of the forging (106 h, 4.2 %), It is attributed to the reduced number of transverse grain boundaries, the finer Laves phase accommodating many dislocations, and γ" phase promoting the formation of stacking faults, Lomer-Cottrell locks and nanotwins. The findings demonstrate the great potential of additively manufactured microstructure in properties enhancement, and may be enlightening for the development of novel customized high-temperature alloys.

Effect of grain structure on the magnetic properties of AlNiCo 8 alloys

AlNiCo alloy has gained popularity again in recent years due to its good corrosion resistance, affordability, and superior performance at high temperature. However, the lower magnetic properties of AlNiCo limit its wide variety of applications. Directional solidification process is a key process that affects the properties of AlNiCo alloy. During the solidification process, grains with various structures are formed due to the difference of cooling rate at different positions of the ingot. As the cooling rate slows down, the average grain size gradually increases, and orientation degree of the grains becomes better, resulting in the increase of coercivity (Hc) and remanence (Br). Therefore, the top sample has the best Hc and Br, the bottom is the worst, and the middle is between the two. It is found that when the average grain size increases, the percentage of transverse grain boundaries and high angle grain boundaries (HAGBs) decrease, the truncated α1 phase decreases, and the Hc rises, whereas the magnetic moment along the easy-axis direction is not affected by the external magnetic field when the grain orientation coincides, and the Br value increases, and the Br value increases. Large and highly oriented grains are associated with excellent performance, providing a new method to enhancing magnetic properties by regulating the grain structure.

Microstructure and mechanical properties of Cu–Cr–Zr–ZrB2 composites by novel fabrication process of ultrasonic vibration treatment

Copper matrix composites with dual-scale particles were fabricated through casting with reaction. Ultrasonic vibration has been successfully introduced into the melt at about 1523 K while the microstructural development and mechanism of copper matrix composites with high-performance through a novel method of casting with ultrasonic vibration treatment are investigated. When ultrasonic vibration is applied, the distribution of micro-scale particles is greatly improved. Primary Cr phase convents to non-dendrite and large aggregates of ZrB2 particles are disrupted into small clusters because of acoustic cavitation and acoustic streaming. The ultimate tensile strength and elongation of Cu-1wt%Cr-0.3 wt%Zr-1wt%ZrB2 composite in as-cast state were 321 MPa and 14.37 %, recording a 28.4 % and 14 % increment respectively compared with the sample without treatment. After solution treatment, deformation and aging subsequently, the uniform distribution of reinforcements also decreases the average transverse grain thickness and increases the dislocation density which improve the comprehensive properties.

Enhanced tensile performance of ternary Fe-Ni-Ti peri-eutectic alloy through directional solidification associated with thermal processing

The microstructural evolution and tensile performance of ternary Fe66.5Ni17.6Ti15.9 peri-eutectic alloy were studied by synergetic modulation of directional solidification and thermal processing technique. The alloy after directional solidification consisted of the vertically growing α-Fe dendrites plus interdendritic γ-Fe(Ni) + Fe2Ti peri-eutectic. The in suit thermal processing promoted the precipitation transition of the α-Fe dendrites, and the lamellar Fe2Ti precipitate was formed along the α-Fe grain boundaries with different orientation relationships. Compared to the conventional solidification, the synergetic modulation not only reduced the transverse grain boundaries and hindered the crack propagation, but also introduced the second phase strengthening and impeded the dislocation movement in the α-Fe dendrites. Eventually, the tensile strength and Young’s modulus of this peri-eutectic alloy were enhanced by 253 % and 72 %.

Flexural behavior and load-bearing capacity calculation methodology for wooden beams strengthened using aluminum plates attached with self-tapping screws

ABSTRACT To investigate the flexural failure mode and behavior of wooden beams strengthened using aluminum (Al) plates, which were attached with self-tapping screws and structural adhesive, ten specimens were tested in bending. The experimental parameters were the thickness of the bottom Al plate, the longitudinal and transverse grain spacing of the self-tapping screws. The experimental results revealed that (1) compared with unreinforced beams, the reinforced beams exhibited ultimate load capacity and displacement ductility coefficients that were 18.4%–54.3% and 6.4%–43.1% higher, respectively; (2) for the same Al plate thickness in the tensioned area, the initial stiffness of the reinforced wooden beams increases as the longitudinal grain spacing of the screw grains decreases; (3) the plane-section assumption was satisfied by the strain in the middle section of the Al plate-reinforced wooden beam along the height; (4) the strains at the same position in the wooden beam and Al plate were similar, thus indicating that the wooden beam and Al plate behaved collectively. Furthermore, a formula was proposed for calculating the flexural capacity of an Al plate-reinforced wooden beam, thus providing a valuable reference when designing wooden beam reinforcements.

Effect of Friction Stir Welding and Tempering on the Microstructure and Strength of a Tempformed Low-Alloy Steel

The microstructure developed in a low-alloy steel during friction stir welding and post-weld tempering was studied. The quenched steel samples were subjected to tempering at 650 °C for 1 h, followed by warm rolling to a total strain of 1.5 at the same temperature. The processed steel samples were characterized by an ultrafine-grained microstructure of the lamellar type with a transverse grain size of 360 nm and exhibited an yield strength of about 1200 MPa and a total elongation of 13%. Then, the steel plates were joined by friction stir welding. The yield strength of the weld joint was about 1170 MPa, although the total elongation decreased to 1.5%. The martensite microstructure, with a high-angle grain boundary spacing of about 800 nm, was developed in the stir zone. This martensite in the stir zone originated from the ultrafine-grained prior austenite, resulting in an almost two-fold increase in hardness as compared to the base material. Tempering of the welded sample at 650 °C for 1 h resulted in a decrease in the hardness of the weld joint to the level of the base material. Nevertheless, the fracture of the welded and tempered sample occurred in the base material. The yield strength of the welded sample after tempering was 930 MPa, with a total elongation of 13%.

Intermetallic compound evolution and mechanical properties of Sn-0.7Cu-0.1Ni-xZn lead-free solder alloys prepared by directional solidification

The addition of Ni and Zn is known to improve the properties of Sn-0.7Cu solder. However, previous research has only focused on the improvement of Sn-0.7Cu solder performance through microalloying methods, and the impact of preparation processes and microalloying on the properties of Sn-0.7Cu solder remains unclear. In this study, Sn-0.7Cu-0.1Ni-xZn solders were prepared using the directional solidification (DS) method. DS eliminates transverse grain boundaries, making it an advantageous method to study the effect of Zn content on the mechanical properties of Sn-0.7Cu-0.1Ni solder. The results showed that some CuZn intermetallic compounds (IMCs) and Cu6Sn5 IMCs transformed into Cu5Zn8 IMCs of better mechanical properties and (Cu,Ni)6(Sn,Zn)5 IMCs of more thermodynamic stability with the increase of Zn content. The tensile results indicated that the ultimate tensile strength (UTS) and yield strength (YS) of the solders followed the same pattern as the Zn content increased. Additionally, the fracture elongation (EL) of the solders initially increased and then decreased with the increase of Zn content. The peak EL was observed at 21.9% when the Zn content was 0.5 wt%. Finally, the fracture surface analysis of the tensile specimens revealed that the solder deformation was primarily plastic, with a small degree of necking observed.

Strength and ductility dual-enhancement of Ni36Co30Fe11Cr11Al6Ti5Nb1 high entropy alloy by directional solidification

Ni36Co30Fe11Cr11Al6Ti5Nb1 high entropy alloys (HEAs) were prepared by directional solidification. The effect of solidification rate on microstructure evolution and mechanical properties was systematically investigated. Results show that the microstructure has a dendritic morphology with uniform orientation. FCC phase rich in Co, Cr and Ni is formed in the dendrite. Laves phase rich in Nb and Ti and FCC phase rich in Ni and Ti are formed between dendrites. With the increase of solidification rate, the dendrites are gradually refined. Tensile results show that the yield strength and elongation increase with the increase of solidification rate. The yield strength and elongation at 100 μm/s are 606.2 MPa and 27.6 %, respectively, achieving an excellent combination of strength and plasticity. Fine-grain strengthening, second-phase strengthening and solid-solution strengthening are the dominant strengthening mechanisms. The dendrites growing along the directional direction reduce the transverse grain boundaries and avoid the rapid propagation of cracks.

Unveiling the failure mechanism on creep response of a casting Ni-based superalloy in thin-wall thickness

With the improvement of thermal efficiency and the lightweight tendency of engine blades, Ni-based superalloy is widely used owing to its excellent performance in high-temperature atmospheres. This work studied the effects of surface oxidation, internal environmental attack, and matrix damage on the failure mechanism in a thin-walled casting Ni-based superalloy at 980 °C/160 Mpa. At the edge of the fracture, the sample suffered a severe environmental attack, resulting in the oxidation-affected zone forms. However, the loss of effective bear area induced by surface damage could not be the main reason for the sample's failure. At the interior of the matrix, voids were preferably initiated at the interface of MC carbides. As the increase of creep deformation, dynamic recrystallization (DRX) occurred at the tip of the voids, which increased the transverse grain boundaries and promoted crack propagation. Moreover, the DRX provided a short penetration path for the nitrogen, causing internal nitridation with AlN and Ti(Ta)N to precipitate. EBSD analysis confirmed that nitrides induced significant dislocations to accumulate at the boundaries of nitrides/γ, accelerating the failure of the sample.

Strong cooperation growth of two phases in the ternary eutectic

The growth mechanism and tensile performance of ternary Ni40.6Fe36.4Ti23 alloy were investigated using directional solidification technique. The ternary Fe2Ti+γ-Fe(Ni)+Ni3Ti eutectic formed a lamellar structure under the steady state growth. After quenching, the Fe2Ti phase transformed into independently grown fiber while the γ-Fe(Ni) and Ni3Ti phases kept lamellar structure. It was confirmed that the solid/solid interfacial energy anisotropy contributed to the strong cooperation growth of the two phases in the ternary eutectic. The γ-Fe(Ni)/Ni3Ti interface preferred to be parallel to the common planes of {111}γ and {0001}Ni3Ti with low interfacial energy, leading to the formation of the stable lamellar structure under different solidification conditions. Owing to the reduction of transverse grain boundaries and grain refinement, the alloy solidified at 10 μm/s growth velocity showed the highest tensile strength and Young's modulus with translamellar fracture mechanism.

Tensile strength of a transverse grain boundary in a single-walled carbon nanotube

Tensile strength of a transverse grain boundary in a single-walled carbon nanotube

Grain design in ultra-fine Al wire with remarkable combination of strength and conductivity: Ultra-fine-long grains with super strong 〈111〉 texture

The trade-off relation between the strength and electrical conductivity (EC) limits the further application of Al wires in the automotive electronic wiring harnesses. In this work, an ultra-fine pure Al wire (UFPAW) with a diameter of around 0.2 mm was successfully prepared by the process of cold drawing → intermediate annealing → cold drawing. It was quantitatively revealed that the ultra-fine grains in the radial section together with the super strong 〈111〉 texture could provide remarkable grain boundary strengthening and texture strengthening, resulting in an ultra-high strength of the UFPAW (228.3 MPa). Besides, the axial long grains could weaken the electron scattering due to the reduction of transverse grain boundaries, leading to a high EC of the UFPAW (63.14 %IACS). Consequently, the ultra-fine-long grains with super strong 〈111〉 texture were proved to be the dominant factors in achieving ultra-high strength and high EC of the UFPAW.

Investigating the buckling deformation of thin metal sheets during the blanking process

This article describes the effect of the generated stresses due to the cutting process on the possibility of the occurrence of buckling deformation in a thin sheet, which could affect the performance of the cut part, especially for some applications such as the cutting of the thin sheet laminations of motor parts. To achieve the research objectives, an experimental approach was followed. Two different thicknesses and two-grain orientations of silicon steel material were applied to investigate the influence of thickness and grain orientation upon the induced buckling deformation. Blanking dies were designed to cut thin sheets of steel at different cutting speeds. Buckling height was measured optically using a 3D microscope with regard to the cutting parameters. The results showed the appearance of buckling deformation only at low sheet thickness. The maximum buckling height was about 164 µm (82% of the material thickness) in the transverse grain direction at the lower cutting speed. Meanwhile, the results also demonstrated the presence of an elongation in the material of approximately 90 µm (1.8%) on the cutting sides, which played a role in the application of pressure to all sides of the cut plate, resulting in the formation of a plastic buckling deformation prior to the completion of the cutting process, and thus the occurrence of the buckling phenomenon.

Improved temperature and grain size consistency of continuous cast slabs through cooling spray regulation

ABSTRACT The consistency of temperature and grain size is crucial to the quality of the continuous casting slab. In order to study the temperature and grain size of the continuous casting slab as influenced by the cooling spray state, a cellular automatic finite element (CAFE) coupled model was developed. The model was validated by low magnification inspection and infrared temperature measurement. The process of continuous casting was simulated by numerical model. Temperature and grain size distribution in the transverse direction of the continuous casting slab can be controlled by adjusting the nozzle arrangement. The effect of different nozzle positions on the temperature field distribution in the second cooling zone of continuous casting was simulated. The optimal nozzle position was selected with the temperature distribution uniformity as the important index. When the optimized nozzle arrangement is selected, the transverse temperature and grain size of the continuous casting slab are more uniform.

An Example of the Use of Traditional Woodworking Hand Tools in Product Design Studies at the Institute of Design Technologies of the Faculty of Materials Science and Applied Chemistry of Riga Technical University

Initially, hand tools were created to facilitate the processing of materials in manufacturing utility items. Tool design, technology, and ergonomics evolved along with the growing human ability to process new materials. The tool range has expanded to meet more diverse needs of the woodworking industry, adapting the tools for both universal use and specific functions. Understanding of the functionalities of woodworking hand tools is essential for observing the sequence of material processing and practical processing operations, as well as in building awareness of the properties of the wood material. This is ensured by the interaction between the operator, the tool, and the workpiece. An important aspect in raising awareness is the relatively low processing speed and the processing of the material with human-controlled movements. Treatment of wood with craft methods and tools reveals the characteristic properties of the material, including specifics of wood grain direction, the difference in the density of earlywood and latewood, and the difference in the longitudinal and transverse grain direction. It also allows understanding the most typical wood defects. To make the process of learning a wood material meaningful in the study process, it is integrated with product manufacturing, making students create a wooden puzzle. This process implies running a sequential crafting process from a solid pine board to a finished and functional product – a puzzle. Students have to make it following a uniform design drawing showing the proportions of the pieces and joints. While making a wooden puzzle, students choose the most appropriate tools for each processing stage. In the process, it is necessary to check, measure, mark, and cut the workpiece. The result is a three-dimensional product that may be assembled and disassembled. The assembly and disassembly process allows appreciating the role of processing accuracy in the course of work and its impact on the end result.

Tradicionālo kokapstrādes rokas instrumentu lietojuma piemērs produktu dizaina studijās Rīgas Tehniskās universitātes Materiālzinātnes un lietišķās ķīmijas fakultātes Dizaina tehnoloģiju institūtā

Initially, hand tools were created to facilitate the processing of materials in manufacturing utility items. Tool design, technology, and ergonomics evolved along with the growing human ability to process new materials. The tool range has expanded to meet more diverse needs of the woodworking industry, adapting the tools for both universal use and specific functions. Understanding of the functionalities of woodworking hand tools is essential for observing the sequence of material processing and practical processing operations, as well as in building awareness of the properties of the wood material. This is ensured by the interaction between the operator, the tool, and the workpiece. An important aspect in raising awareness is the relatively low processing speed and the processing of the material with human-controlled movements. Treatment of wood with craft methods and tools reveals the characteristic properties of the material, including specifics of wood grain direction, the difference in the density of earlywood and latewood, and the difference in the longitudinal and transverse grain direction. It also allows understanding the most typical wood defects. To make the process of learning a wood material meaningful in the study process, it is integrated with product manufacturing, making students create a wooden puzzle. This process implies running a sequential crafting process from a solid pine board to a finished and functional product – a puzzle. Students have to make it following a uniform design drawing showing the proportions of the pieces and joints.

玉米播种位置动态补偿系统设计与台架试验分析

Aiming at the problem that the existing planters cannot accurately maintain the seeding spacing and row spacing in the field, the high-speed photography technology is used to analyze the seeding trajectory, so as to determine the key factors affecting the seeding position. First, a dynamic compensation system for maize seeding position based on fuzzy PID control was designed. In the dynamic compensation system, the biaxial angle sensor was used to detect the angle of seeding monomer, and the space rotation theory was used to calculate the offset of the seeding position. Then, the dynamic compensation of seeding position was completed by the fuzzy PID control servo electric push rod, and the response time of fuzzy PID control system was 0.035 s. When the seed spacing of maize was 30 cm, the conveyor speed was 1.67 m/s and the seed tray speed was 30 r/min. Finally, the bench test was carried out under the conditions of random disturbance signal, sinusoidal wave disturbance signal and random disturbance signal plus sinusoidal wave disturbance signal. The results showed that compared without dynamic compensation, the variation coefficient of the longitudinal grain spacing and the transverse grain spacing decreased by an average of 6.94 % and 9.16 %, respectively. In this way, this study can provide a reference for improving the stability of seeding row spacing and plant spacing.

Tempforming Strengthening of a Low-Alloy Steel.

Low-alloy structural steels subjected to quenching and tempering to achieve high strength possess a common drawback associated with low-impact toughness at low temperatures. An additional warm rolling, i.e., tempforming, is a promising approach to strengthen the rolled semi-products along with increasing their impact toughness. The effect of tempforming at 823–923 K on the microstructures and the mechanical properties of a low-alloy steel was studied in comparison with ordinary tempering at the same temperatures. The tempformed microstructures consisted of highly flattened grains with a transverse grain size of 245 nm to 360 nm depending on tempering temperature. A decrease in the transverse grain size with a decreasing temperature was accompanied by an increase in the total dislocation density (including sub-boundary dislocations) from 3.3 × 1015 m−2 to 5.9 × 1015 m−2. The steel samples subjected to tempforming exhibited enhanced mechanical properties. The yield strength increased by more than 300 MPa, approaching about 1200–1500 MPa depending on tempforming temperature. Moreover, strengthening by tempforming was accompanied by an increase in the impact toughness, especially inthe low temperature range down to 77 K, where the impact toughness was above 80 J cm−2.

Transverse and Longitudinal Degradations in Ceramic Solid Electrolytes

Ceramic solid electrolytes conducting primarily a specific ion but with minuscule electron leakage are used in many electrochemical devices. Their degradation phenomena may be classified into two broad categories─a slow transverse mode accumulating damage normal to the ionic current direction and a fast longitudinal mode accumulating degradation parallel to the current direction. Examples of the transverse mode include oxygen bubbles on transverse grain boundaries, in-plane electrolyte cracking in solid oxide electrolysis cells, and cathodic reduction of beta-alumina electrolytes in Na–S batteries. Examples of the longitudinal mode include short-circuiting dendrite formation in metal batteries of both the Na–S type and the all-solid-state lithium metal type. Analogous instability modes are also seen in field-assisted ceramic processing, dielectric devices, and memristors. These phenomenological similarities across different devices, operating conditions, and technologies, as well as the origins of their damage mechanisms, can be understood in terms of the highly nonlinear spatial distributions of the minority carriers (electron/hole) and the chemical potential of the equivalent charge-neutral species such as O2; such distributions can in turn cause or exacerbate damaging concentrations of stress and electric fields. This review also outlines strategies for improving material designs to mitigate degradation, which will be especially important for operations and applications under extreme electrochemical conditions.