The deformation after cooling from 1200 degrees C to 800 degrees C failed to produce ultrafine grains in M50NiL martensitic steel, whereas directly heating to 800 degrees C successfully fabricated ultrafine grains (0.39 mu m). This abnormality stemmed from the different initial microstructures before deformation-namely, austenite and tempered martensite. The ultrafine-grained M50NiL steel (1.4 mu m) prepared by forging at 800-850 degrees C exhibited markedly higher strength and toughness than the coarse-grained steel (75 mu m) produced by conventional forging, owing to significant grain refinement. Furthermore, forging as-cast M50NiL steel at 800-850 degrees C could simultaneously produce ultrafine grains and achieve compositional homogenization, offering great potential for substantially shortening the processing route for ultrafine-grained steels.

The tension-torsion multipath cyclic loading experiments of the nonlinear viscoelastic adhesive bonding butt joints were conducted with the asymmetric strain-control mode, and the effect of loading path and strain strength on the mechanical behavior of the joint was observed through the dissipated energy and the cyclic stress response. It was found that the loading path had influences on the fatigue damage and nonproportional strain loading path had additional fatigue damage to the joints. Meanwhile, the initial decline rate of dissipated energy and cyclic stress increased with the increase of equivalent mean strain (EMS) and equivalent strain amplitude (ESA) have been observed. In addition, the uniaxial cyclic damage model was extended to a tension-torsion fatigue damage model by adding a path factor into the tensile and torsional cyclic damage model. The model calculated results showed that the proposed model could better predict the loading path-dependent fatigue behavior of the joint.

This study investigates the potential use of Yellow River sand (YRS) sourced from the lower reaches of the Yellow River in China as a sustainable and cost-effective substitute for quartz sand in engineered cementitious composites (ECCs). This region accumulates around 400 million tons of sand annually. The study evaluates the impact of different YRS replacement percentages (0, 25, 50, 75, and 100%) on mechanical and microstructure properties under freeze-thaw conditions, focusing on assessing the ECC durability during cooling cycles. The results show that YRS exhibits a smaller normal distribution of particle sizes compared to that of quartz sand and a 5.77 times greater specific surface area, affecting the ECC particle size distribution. After 300 cooling cycles, the R25 group maintains 97.5% of the initial mass and 79.4% of flexural strength, indicating superior durability. The R25 group also demonstrates a minimal decrease of 11.5% in equivalent bending strength, reaching a level of 104.4% compared to R0. The R25 group's porosity is 30.80%, with an average pore size of 20.47 mm, showing 1.3% and 6.7% decreases compared to the R0 group. Additionally, this study establishes a failure progression equation using the Weibull probability distribution model, with calculated values closely aligning with measured values. Overall, this study recommends using YRS as a sustainable ECC material.

Uniaxial and biaxial multi-path cyclic loading experiments were carried out using the plate dumbbell-shaped specimens and the cruciform-shaped specimens prepared by silane-modified polyurethane adhesive, respectively. The uniaxial testing results showed that the stress–strain curve of the material was nonlinear, and its mechanical properties were viscoelastic. The adhesive exhibited cyclic softening and cyclic strain increase (cyclic creep and cyclic strain accumulation) under the tensile cyclic loading. The biaxial multi-path testing results showed that the non-proportional loading path caused additional ratcheting strain, which was related to different loading paths. According to the experimental observation, a uniaxial cyclic constitutive model was proposed. Furthermore, a biaxial cyclic constitutive model of the material was developed by introducing the loading path coefficient. By comparing the model prediction results with the experimental data, it was shown that the evolution of ratcheting strain and cyclic softening of the material under uniaxial cyclic loading was accurately described using the proposed model. Also, the biaxial cyclic constitutive model can well predict the mechanical behaviors of silane-modified polyurethane adhesive under biaxial multi-path cyclic loading.

Rare earth(RE)elements are excellent modifiers for non-metallic inclusions that inevitably appear in steel and affect steel properties.This paper reviews the research status of inclusions modification by RE elements and the changes it cause on steel properties.First,the inclusion changes caused by RE modi-fication are described.Generally,after adding pure RE,the main evolution of inclusions occurs as M→M+RE-Al-O→ RE-Al-O+RE2O2S→ RE2O2S+RE-S/RE2O2S+RE-O with an increase in the RE content(M represents the inclusions before RE addition).The type of final inclusion obtained after RE modification is related to the relative contents of S and O in the steel.Moreover,fine,regular,and uniformly distributed inclusions can be obtained with appropriate RE addition.However,the effective-ness of inclusions modification by adding both RE and non-RE elements is closely related to the order of their addition.Second,the applications and advantages of thermodynamic calculations in the study of RE-modified inclusions are introduced.Third,the changes in the corrosion resistance,impact properties,and other properties of steel caused by the modification of inclusions by RE are reviewed.Finally,the perspectives and trends of inclusions modified by RE elements in the steel industry are presented.

The biaxial tension-tension cyclic loading experiments were conducted on the cruciform specimens prepared using a silane-modified polyurethane sealant to investigate their mechanical behavior. The finite element method was employed to validate the mechanical behavior of cruciform specimens under the biaxial cyclic loading conditions. It is shown that the highest stress concentration is in the central region of the cruciform specimens, indicating that the shape design of the specimen is suitable for the biaxial tension-tension cyclic tests. Additionally, the effects of loading path, mean stress, and stress amplitude on ratcheting strain and dissipated energy were analyzed through the experimental data. The experimental results demonstrated that the loading path had an influence on the mechanical behavior of the cruciform specimen. The additional ratcheting strain caused by the non-proportional loading path was found to be loading path dependent of the adhesive. Moreover, the mean stress and stress amplitude greatly affected the strain response curves of the specimen under biaxial cyclic loading. The ratcheting strain and dissipated energy increased with increasing mean stress and stress amplitude; nevertheless, stress amplitude had more influence on the mechanical behavior than the mean stress. The biaxial cyclic loading tests were conducted on the cruciform specimens. The effects on ratcheting strain and dissipated energy were analyzed. The loading path has influences on the mechanical response of the specimen. The mean stress and stress amplitude have effects on the strain response

The widespread use of refrigerants results in ozone depletion and greenhouse gas emissions. As new refrigerants replace older ones, the proper disposal of discarded refrigerants becomes crucial for the sustainability of human society. This work proposes photo-thermal coupling catalysis for the degradation of 1,1,1,2-Tetrafluoroethane (R134a). This method enhances light absorption efficiency and transforms absorbed energy into thermal energy, thereby improving the degradation efficiency of R134a. To enhance stability and efficiency, a composite of gamma-Al2O3@C3N4 was synthesized as a photo-thermal catalyst. Experimental findings demonstrate that photothermal coupling catalysis achieves an R134a degradation efficiency of 52.9 % within 40 minutes, which is 4.90 and 1.79 times higher than those of photocatalysis and thermocatalysis, respectively. Additionally, photothermal coupling catalysis effectively mitigates the instability and deactivation seen in traditional thermal catalysis processes. These results suggest that the proposed photo-thermal coupling catalysis is an effective approach for the efficient and low-energy degradation of R134a, offering a promising avenue for refrigerant disposal.

M50NiL bearing steel is widely used in the aerospace field because of its excellent properties. δ ferrite would affect the impact toughness of steel, but there is little research on it in M50NiL bearing steel. In this study, the effect of the δ-ferrite content on the impact toughness of M50NiL bearing steel and the corresponding mechanism were investigated through microstructure characterization and mechanical property testing. The results indicated that the impact toughness of the steel at room temperature, as well as the energy needed for crack initiation and crack propagation, improved with δ-ferrite content reduction. This suggests that the presence of δ ferrite in M50NiL steel is detrimental to its impact toughness and that reducing the δ-ferrite content can suppress crack initiation and crack propagation, significantly improving the impact toughness. The adverse effect of δ ferrite on impact toughness is mainly attributed to the fact that δ ferrite is prone to crack initiation and cannot effectively prevent crack propagation due to its low strength and shear resistance. Additionally, the difference in microstructure and strength between the δ ferrite and martensite matrix may weaken the interface, which is conducive to crack initiation and rapid propagation.

This study examines the impact of the recycled brick powder (RBP) replacement rate, especially at elevated temperatures on RBP-ultra-high-performance concrete (UHPC) properties such as the stress–strain curve, Poisson’s ratio, elastic modulus, and axial compressive strength through uniaxial compression experiments. The results show that with the increase of heating temperature, the axial compressive strength of the specimen increases first and then decreases under natural cooling (NC). In contrast, Poisson’s ratio shows opposite values. The peak strain continues to increase, and the initial elastic modulus and peak secant modulus continue to decrease. Compared with NC, the axial compressive strength of the specimens under water cooling has been reduced, the peak strain is generally larger, the initial elastic modulus and the peak secant modulus are smaller, and the incorporation of RBP also has a certain effect on the mechanical properties. Through regression analysis, an equation is established to calculate the axial compressive strength of RBP-UHPC with temperature, accounting for variables such as temperature, RBP replacement rate, and cooling method. Furthermore, based on the results of axial compression experiments, a constitutive equation for axial compression in RBP-UHPC after exposure to high temperatures is proposed. Overall, the theoretical curve closely aligns with the experimental curve, verifying its accuracy.

CFRP hybrid bonded-bolted (HBB) joints combine the advantages of traditional joining methods, namely adhesive bonding, and bolting, to achieve optimal connection performance, making them the most favored connection method. The structural parameters of CFRP HBB joints, including overlap length, bolt-hole spacing, and fit clearance relationships, have a complex impact on connection performance. To enhance the connectivity performance of joint structures, this paper develops a multiscale finite element analysis model to investigate the impact of structural parameters on the strength of CFRP HBB joint structures. Coupled with experimental validation, the study reveals how changes in structural parameters affect the unidirectional tensile failure force of the joints. Building on this, an analytical approach and inverse design methodology for the mechanical properties of CFRP HBB joints based on deep supervised learning algorithms are developed. Neural networks accurately and efficiently predict the performance of joints with unprecedented combinations of parameters, thus expediting the inverse design process. This research combines experimentation and multiscale finite element analysis to explore the unknown relationships between the mechanical properties of CFRP HBB joints and their structural parameters. Furthermore, leveraging DNN neural networks, a rapid calculation method for the mechanical properties of hybrid joints is proposed. The findings lay the groundwork for the broader application and more intricate design of composite materials and their connection structures.

The development of efficient and stable catalyst is crucial for hydrogen evolution reaction (HER) in water electrolysis. The rational design of porous supports can effectively improve the exposure of active sites and in-crease the electrochemically active surface area of catalysts. In this study, a nanostructured carbon nanoshell (CS) is proposed for the synthesis of ruthenium and nitrogen incorporated carbon catalyst (CS@N-Ru) catalysts. Physicochemical characterization show that the prepared catalyst exhibits a hollow structure and abundant nitrogen/ruthenium related active sites, which enables the improvement of mass transfer and the catalytic ac-tivity. The electrochemical tests show that the prepared CS remarkably facilitates the performance of catalyst, the CS@N-Ru500 synthesized at 500 degrees C exhibits the best catalytic activity with a low overpotential of 35 mV at 10 mA/cm2 and Tafel slope of 38 mV/dec, attributing to the increased electrochemically active surface area, reduced electron/ion transfer resistance, and accelerated kinetics of HER. These findings suggest that the CS@N-Ru can be a promising alternative to Pt/C for HER in water electrolysis.

The mechanical behaviors of TB991 weld sealant under cyclic loading conditions were experimentally investigated. The evolution of relaxation stress, cyclic softening, and dissipated energy was evaluated with the effect of strain amplitude and mean strain. The experimental results showed that the stress-strain response curves of the first loading-unloading and cyclic loading-unloading were significantly different. The phenomenon of stress relaxation and cyclic softening occurred under cyclic strain loading conditions. Furthermore, the relaxation stress and dissipated energy decreased rapidly during the initial cyclic loading and then steadily decreased with the increase of cycle number, while the cyclic softening increased rapidly at first and then steadily. Besides, a viscoelastic constitutive model was proposed which can describe the different shapes of stress-strain curve between the initial loading-unloading and the cyclic loading-unloading and also considers the cyclic stress relaxation and cyclic softening of the materials under cyclic loading condition. Comparisons between the numerical results and the experimental data demonstrated that the proposed model can better describe the mechanical behavior of TB991 weld sealant under cyclic loading conditions.

The processing map for M50NiL steel was established by hot compression tests at temperatures of 950-1150 & DEG;C and strain rates of 0.002-1.0 s- 1. Based on the experimental results of hot compression tests, the predictability in both reproducing experimental flow stresses and predicting flow stresses using the Arrhenius, physical-based, and artificial neural network (ANN) models was compared. The results showed that the average absolute rela-tive errors of Arrhenius, physical-based, and ANN models in both reproducing and predicting flow stresses were 6.04 % and 8.01 %, 6.61 % and 7.78 %, and 1.91 % and 4.74 %, respectively. The ANN model had a considerably higher accuracy in reproducing and predicting flow stresses than the other two models. In addition, a processing map of M50NiL steel was established using the predicted flow stresses by the ANN model. This processing map indicated that the optimized processing parameters were 975-1050 & DEG;C/0.01-0.002 s- 1. Instability occurred during deformation at 950-975 & DEG;C at 1.0 s- 1 and 1075-1150 & DEG;C at 0.01 s- 1. The instability prediction was verified by the microstructure evolution.

The fatigue life evaluation of adhesively bonded joints has attracted more and more attention with its extensive application. Here, the fatigue experiments under various loading conditions were carried out to understand the stress amplitude, mean stress, cycle period, and loading path related to the fatigue life of the adhesively bonded tubular butt-joints. The experimental results showed that the fatigue life of the adhesively bonded butt-joint decreased with the increase of stress amplitude and mean stress, and the influence of cycle period on the fatigue life was more obvious since the mechanical property of the selected adhesive was rate dependent. Meanwhile, the fatigue life of the adhesively bonded butt-joint was influenced by the loading path under multiaxial loading conditions. In addition, the relationship between the damage parameters and fatigue life was characterized based on the experimental observations. Accordingly, a stress-based fatigue life prediction model was developed which can simultaneously consider multiple damage parameters related to fatigue life of the adhesively bonded joint. The predicted results indicated that the predicted life correlated well with the experimental data of the adhesively bonded joints.

The hierarchical martensite structure of secondary hardening low‐carbon high‐alloy bearing steel at different solution temperatures is characterized in detail, and the effect of microstructural evolution on mechanical properties of the experimental steel is studied. The results show there are a large number of micron‐M 6 C at the boundary of the prior austenite grain when the solution temperature is 1,000–1,025 °C, which is conducive to hinder the growth of the prior austenite grain and produces smaller packets that improve the yield strength of the material. At the same time, such micron‐M 6 C is prone to stress concentration when the material is subjected to an external force load, which can severely reduce the material toughness. The M 6 C completely dissolves into the matrix when the solution temperature exceeds 1,050 °C, and the packets size grows rapidly with the prior austenite grain size. At this point, the effect of packets on yield strength no longer dominates, and the rate of decrease in yield strength tends to be gradual. Under the comprehensive function of the micron‐M 6 C‐remelting, the martensitic blocks refinement, the increased number of the Σ3 grain boundaries, and the growth of cracks can be hindered, and the toughness of material can be improved accordingly.

The cyclic loading experiments on HP-172B sealant bonded tubular butt-joints were carried out with the strain-controlled mode, and the effects of strain amplitude and mean strain on the cyclic relaxation stress and cyclic softening variable of the bonded butt-joint were investigated. The experimental results show that the stress-strain response curve of the butt-joint presents a corrugated shape under cyclic loading. The cyclic stress relaxation and cyclic softening of the bonded butt-joint occur. The increase of mean strain and strain amplitude intensifies the cyclic stress relaxation and cyclic softening behaviors. According to the experimental observation, a nonlinear viscoelastic model is proposed to predict the mechanical behavior of butt-joints under cyclic loading, which considers the cyclic stress relaxation and cyclic softening of the bonded butt-joint. The comparisons between the model calculation and the experimental data show that the calculated stress-strain curve is in good agreement with the experimental data.

Stress-relaxation and creep experiments of TB991 weld sealant were conducted at different temperatures. The effects of temperature and strain rate on the uniaxial tensile-deformation behavior were investigated. The experimental results demonstrated that the deformation behavior of the weld sealant was nonlinear. The stress-relaxation curves were close to each other, and the creep phenomenon of the materials was pronounced with increasing temperature. Further, the deformation behavior of the material exhibited a rate dependence below the glass-transition temperatures (T-g), while the rate dependence was not significant as the temperature exceeded T-g. A nonlinear viscoelastic damage constitutive model was used to describe the tensile-deformation behavior of TB991 weld sealant, and the damage-softening function in the constitutive model was modified. The comparison between the model prediction and the experimental results demonstrated that the modified constitutive model can well describe the tensile-deformation behavior of TB991 weld sealant under different temperatures and strain rates.

Carbon nanotubes (CNTs) have been proved to be a high-value by-product of hydrogen production which could be obtained through catalytic reforming from waste plastic syngas. Catalyst plays an important role in the growth of carbon nanotubes. The influences of Ni/ZSM-5 catalyst and temperature were performed in a lab-scale tubular reactor. The catalyst and produced carbon were analyzed by different characterization methods. X-ray diffraction, X-ray energy dispersive spectrometer, scanning electron microscopy and transmission electron microscopy. The results showed that in the presence of catalyst, 600 °C is considered the optimal temperature during the operating temperature range of 400 °C~800 °C for carbon yield and hydrogen production rate, the highest carbon yield of 4.83 g/g catalyst (among which the MWCNTs were the main products) and hydrogen production rate of 0.0199 L/min were obtained. Higher catalytic temperature led to higher average diameter of carbon nanotubes, which increased from 39.5 nm to 55.3 nm. The highest carbon nanotubes proportion of 98.08% to total carbon deposition was obtained under the conditions of 800 °C. It suggested that Ni/ZSM-5 catalyst has the potential for high quality carbon nanotubes and H 2 -riched gas production from waste plastic syngas.

In this study, the effects of the annealing temperature and holding time on the δ ferrite content in M50NiL bearing steel are evaluated. The results indicate that when the temperature increases from 900°C to 1200°C, the δ ferrite content increases as a result of the increase in the Cr equivalent in the matrix, which decreases the stability of austenite and promotes the transformation of γ  ⟶  δ . At 1300°C, the δ ferrite content sharply increases because the austenite transforms into δ ferrite in large quantities when heated to the γ  +  δ phase region. When the steel is annealed at 1200°C, the content of δ ferrite first decreases and then increases with increasing holding time (0.5–50 h). Meanwhile, the δ ferrite content reaches the lowest value of 3.5% after 30 h of annealing. The decrease in the δ ferrite content is attributed to the increase in the Ni equivalent in δ ferrite, which promotes the transformation from δ ferrite to austenite. The increase in the δ ferrite content is attributed to the diffusion of Mo and V ferrite-forming elements into grains, resulting in the nucleation of a large amount of δ ferrite.

The low-cycle fatigue experiments of the adhesively bonded hollow cylinder butt-joints were conducted in previous work. The effects of loading path, stress amplitude, mean stress and cycle time on the fatigue life were discussed briefly. The stress-based and energy-based fatigue life prediction models were developed to predict the fatigue life of the adhesively bonded joints, respectively. The effects of loading paths and loading conditions on the fatigue life were considered in the prediction models. The prediction results demonstrated that the stress-based model presented a good prediction by reasonably selecting the loading path coefficients and model constants. Furthermore, the energy-based fatigue life prediction model also achieved an accurate prediction on the multiaxial fatigue life through considering the dissipation energy as fatigue failure parameter. In addition, the neural network based method was adopted to predict the multiaxial fatigue life of the adhesively bonded joints. It was shown that the neural network based method obtained a more accurate prediction for the multiaxial fatigue life of the adhesively bonded joints compared with the previous two prediction models. Moreover, the evaluation of the applicability and accuracy of these three prediction methods was carried out. It indicated that the neural network based method had the simple prediction process and it was more accurate than that of the two models for the multiaxial fatigue life prediction of adhesively bonded joints.