High Plastic Deformation Research Articles

A comparative Study of the Erosive Wear Caused by Organic and Inorganic Abrasive Particles

In this study, erosion tests were conducted to evaluate the abrasivity of organic particles to produce wear on a material surface with higher hardness. The novelty of this research work was that pistachio shells, which are usually waste that ends up in the garbage, were collected, ground and sieved to obtain a sufficient quantity of pistachio angular particles to be used productively to perform these wear tests. Additionally, sea shells were thought of as an alternative to organic abrasives, and these were ground, sieved and prepared to be able to carry out the testing. The erosion tests conducted based on ASTM G76 and SEM images showed typical wear mechanisms such as high plastic deformation (material displacement) characterized by micro-cutting and micro-ploughing actions, grooves with lifted lips in the edges as pistachio grits employed to run the tests. On the other hand, a conventional abrasive as glass bead particles caused huge craters, broken and smeared flakes, ploughing and circumferential cracks on the AISI 420 stainless steel surfaces. The highest erosion rates were reached as glass beads were employed to run the erosion tests. AFM technique was used to show the surface variations after the erosive impacts. The eroded scars produced by pistachio and sea shells allowed us to remark that the proposed organic abrasives could be used for polishing, surface finishing and cleaning applications on surfaces of mechanical elements that are dirty or rusty. This was due to their low density, which led to low and very superficial erosion damage.

Effects of annealing temperature on the formability, mechanical and interface properties of laminated metal composite STS304L/Al1050/STS430

Laminated metallic composites (LMCs) produced by cold roll bonding generate high plastic deformation. After the rolling process, it is essential to promote a post-heat treatment (PHT) to increase adhesion, minimize hardening, and enhance the formability of LMCs. In this research, the effects of PHT at low temperatures (250, 350, and 450°C) on LMCs (STS304/Al1050/STS430) obtained by cold rolling were investigated. The Forming Limit Curve (FLC) and mechanical properties such as ultimate tensile strength (σ_UT), yield strength (σ_Y), elongation (ε), and the anisotropy index (r-value) of the LMC were evaluated. Results indicate the best PHT temperature that combines formability, increased adhesion between layers, and better mechanical properties, such as elongation (ε), which increases from 37% to 55%. At this PHT temperature, the brittle intermetallic layer was not detected, and the FLC showed the best performance. Furthermore, in industrial applications, this PHT condition allows energy savings compared to PHT conditions of high process times (>12 h) and/or temperature (>500°C) reported by several works in the literature.

Effect of Size Distribution of Solid Electrolyte on Tortuosity of Ionic Conductivity

Solid state batteries (SSBs) are expected to be the next-generation of batteries due to their high energy density and safety. To emphasize the battery performance of SSBs, it is crucial to analyze and design the electrode structure. The powder compression process is one of the most important processes for determining the battery structure. Powder compression is a molding method used to transform powders into solid and high-density compacts. The powder properties and compression conditions influence the packing structure and density of compacts. In this study, we elucidated the effect of the size distribution of a sulfide solid electrolyte on the ionic conductivity of pellets. The particle size distributions of lithium phosphorus sulfur chloride (LPSCl), a solid electrolyte with high plastic deformability, were prepared to evaluate its effect on the relative density and electrochemical properties. The average particle size of LPSCl was reduced through the milling process, and the resulting compacts were evaluated by impedance measurement after mixing raw and milled LPSCl with different mass fractions. The ionic conductivity of the compacts was found to be improved with the broadening of the particle size distribution of the solid electrolyte. Furthermore, the effect of the particle size distribution of the solid electrolyte on the electrode structure was also investigated numerically. The numerical simulations were performed in consideration of the actual particle size distribution to evaluate the void fraction and tortuosity of the electrodes. A discrete element method (DEM) can simulate the powder behavior by calculating the motion of individual particles based on Newton’s second law. Edinburgh elasto-plastic adhesive (EEPA) model, which can consider particle plasticity and cohesiveness, was applied as the contact force model. Particle plasticity parameter λ p was calibrated based on force-displacement curves obtained by nanoindentation tests. The compression process was calculated assuming an infinite flat plate. Although the calculated relative densities agreed with the experimental trend, the values differed from the experimental values owing to the disregard of particle shape. In addition, tortuosity was evaluated by the shortest path algorithm using the powder bed obtained from the numerical analyses. An effective tortuosity was calculated by weighting the contributions of the conductive paths by its number of particles. The effective tortuosity also increased due to the higher number of particles generated during the LPSCl milling process. The combination of DEM analysis and the shortest path algorithm, taking into account grain boundary resistance, demonstrated that is was possible to correlate the electrode structure of the SSB with its electrochemical performance.

Technological and Mechanical Studies on Additively Manufactured Cellular Structures Made of the Ultrafuse 316L Composite Filament

Regular cellular materials produced using additive manufacturing (AM) techniques represent a significant development trend in modern engineering materials. Depending on the applied elementary unit cell of topology, it is possible to define the course of the structure deformation process in order to obtain the highest possible energy absorption effectiveness. This feature makes regular cellular structural materials particularly attractive for a number of industrial branches. This paper presents the results of technological trials and the results of experimental studies on the mechanical properties of regular cellular structures made using 3D printing technology under compression test loading conditions. The material used for their production was the Ultrafuse 316L filament and the fused filament fabrication (FFF) technique. The proposed material is a polymer-metal composite with a manufacturing process similar to metal injection moulding (MIM). The adopted research methodology included a feasibility study aimed at achieving material homogeneity and compression tests of the developed and manufactured regular cellular structures under quasi-static loading conditions. Several structural topologies were analysed. Experimental results indicated that regular cellular structures made from 316L steel exhibit high mechanical strength and extensive plastic deformation capabilities. The utilized in this work manufacturing technology used combines the advantages of 3D printing process with the potential of powder metallurgy. The proposed technique of structure manufacturing process is much cheaper than other based on melting metallic powders.

Parameter Calibration of Chaboche Kinematic Hardening Model by Inverse Analysis Using Different Optimization Methods in the Case of Pipe Bending

Drag link is one of the important parts in steering system used in automotive. The ball joint, ball joint housing, and pipe compose the drag link. In this study, finite element analysis is used to simulate the deformation process. St 52 steel material is used. A yield criterion, an associated flow rule, and Chaboche’s kinematic hardening rule were used in the finite ele-ment simulations of processes involving high plastic deformation. A series of low-cycle ten-sile/compression tests is performed to determine the parameters of Chaboche’s kinematic hardening rule. The success of the simulation results depends on the more accuracy of the finding parameters. Some optimization methods are used in the calibration progression of these parameters and the results are compared. For the purpose of optimization, the angle of the pipe after bending is set as 16.6 as soon as possible. As design variables, the Chaboche kinematic hardening rule parameters were adjusted. Consequently, calibrated parameters were obtained for St52 pipe bending. By analysing and verifying the candidate points, opti-mization methods are compared. The optimum parameters are determined as YS=350 MPa, C=2984.3 MPa, and =100 while their initial values are YS=373.806 MPa, C=4016 MPa, and =94. It is concluded that the optimization process gives more consistency in the bending process.

Toward the production of bioblends for the automotive sector: Reuse of recycled polyamide 6,6 to prepare super‐tough biopolyethylene

AbstractPlastics reuse is essential for promoting a sustainable future, especially by mitigating environmental impacts. Recycled polyamide 66 (PA66r) was reused for the produce biopolyethylene (BioPE)‐based blends, aiming to obtain a super‐tough material. Initially, a premix of PA66r with maleic anhydride‐grafted ethylene–propylene–diene (EPDM‐MA) was obtained in an internal mixer. Subsequently, the BioPE/PA66r and BioPE/(PA66r/EPDM‐MA) blends were processed in a twin‐screw extruder and injection molded. The rheological, mechanical, thermal, thermomechanical, structural, and morphological properties were investigated. Torque rheometry indicated an increase in the viscosity of the BioPE/(PA66r/EPDM‐MA) blends compared to BioPE/PA66r, which was confirmed by a reduction in the melt flow index (MFI). EPDM‐MA promoted greater stability in BioPE/(PA66r/EPDM‐MA) blends during processing, reducing the degradation rate and molecular weight loss. The BioPE/(PA66r/EPDM‐MA) blend with the 70/(15/15)% composition exhibited super‐tough behavior, with 822.4 J/m impact strength and 233% elongation at break. Scanning electron microscopy indicated a fracture with high plastic deformation, elongated fibrils, and refined particles (0.64 μm), confirming the high toughness. Apparently, a core‐shell morphology was formed, which favored maintaining tensile strength, Shore D hardness, and heat deflection temperature comparable to pure BioPE. The results indicate potential for application in the automotive industry, contributing to reintroducing recycled material into the production chain.

Mechanical behavior and seismic control performance of a metallic torsional damper for flexible structures

The use of metallic dampers is an effective way to reduce seismic responses and dissipate excessive vibration energy for civil structures. Conventional metallic dampers employed energy dissipation by plastic deformation under bending or shear modes are hard to design, and may cause uniform distribution of stress in the metallic components. In this paper, employing the high plastic deformation capacity of aluminum materials, a metallic torsional damper using a gear and rack device (MTDGRD) is proposed to enhance the control effectiveness for the structural response reduction under earthquakes. The static mechanical behavior and energy dissipation of aluminum metallic components under torsional deformation are experimentally studied. Moreover, the configuration and working principle of the proposed damper are introduced. The dynamic behavior of the proposed damper is experimentally studied. For precise modeling in simulations, the elastic-plastic theory of torsional deformation is used to derive the mechanical model of the proposed damper and the model accuracy is validated by experimental data. Finally, numerical simulations under different seismic ground motions controlled by a proposed MTDGRD are compared to that controlled by a conventional tuned mass damper (TMD) for a 10-floor flexible structure. The results show that aluminum 6061# of the energy dissipation capacity is higher than aluminum 1060#. The dynamical tests show that the loading frequency and operational cycles have very limited effect on mechanical behavior and energy consumption capacity of the MTDGRD. The proposed dynamic mechanical model of the MTDGRD has considerable accuracy in numerical simulations and seismic control simulations show the better performance of the proposed damper in reducing structural displacement responses than the conventional TMD with a mass ratio of 0.5 %.

Cut-resistance of elastic high-performance composite yarn

Soft and lightweight personal protective equipment for civil or military use that is made of cut-resistant textiles is usually rigid and heavy, less elastic or flexible. Insertion of elastane fiber during the fabrication of rigid textiles seems to be working, but actually is not. Therefore, it presents a severe challenge in achieving an appropriate balance among elasticity, flexibility, and protection. To address this issue, an elastic cut-resistant composite yarn is fabricated by single wrapping ultra-high molecular weight polyethylene around elastic Spandex. The effects of wrapping parameters (including the twist, spindle speed, and yarn combination) on yarn elasticity and coverage are investigated to achieve a perfect wrapping, and the cut-resistance of the composite yarn is evaluated by using a self-improved AUTOGRAPH universal testing machine. It demonstrates that the cutting process of the composite yarn consists of four stages, the cut modulus and yarn elasticity are highly correlated with yarn structure and wrapping process parameters. The optimizing coverage and cut-resistance are achieved when the twist is 750 t/m, which is also with a high elastic recovery rate (79.79%) and low plastic deformation rate (10.11%). Groups of parallelized composite yarns with varying densities are fabricated by self-improved sample holders to simulate the cut-resistant weaving fabrics with different weaving densities, of which the cut-resistance is evaluated. The resistance against cutting varies significantly among different groups, which is directly proportional to their densities. Finally, two types of elastic cut-resistant fabrics with different structures are woven from fabricated elastic cut-resistant composite yarns practically. Both weft-backed weave and the double-layer weave fabrics have good flexibility and protection, of which the cut-resistance is level 1 and level 2, respectively. Thus, the composite yarn has an excellent elasticity and maintained cut-resistance, which is an ideal material for the production of highly elastic protective textiles.

Properties and microstructure of soil solidified by titanium slag-flue gas desulfurized gypsum-Portland cement composites as solidifiers

Using Portland cement for soil solidification has sustainability issues due to high energy-consumption and carbon emissions. An innovative approach suggests using titanium slag and flue gas desulfurized gypsum as substitutes for Portland cement for soil solidification. This study systematically evaluates the effects of titanium slag-flue gas desulfurized gypsum-Portland cement composite (TS-FGD-OPC composite) solidifier on the performance of solidified soils. The evaluation includes assessing the unconfined compressive strength (UCS), elastic modulus, moisture content, and leachate pH value. Additionally, the hydration process and microstructure development of the solidified soils are characterized through the XRD, TG-DSC, BET, and SEM tests. The results indicate that the although its compressive strength is much lower, TS-FGD-OPC composite can be used as soil solidifier. With the titanium slag content increase, the TS-FGD-OPC composite solidifier brings the solidified soils to have lower UCS, elastic modulus and leachate pH value, and higher plastic deformation and moisture content. However, to get the same UCS, the utilization of the TS-FGD-OPC composite solidifier can bring the significant reduction of the Portland cement consumption. At the same dosage, the TS-FGD-OPC composite incorporating 50 % titanium slag and 20 % flue gas desulfurized gypsum yields an UCS achieving up to 92.5 % of that in pure Portland cement solidified soil. This is attributed to the filling of pores between soil particles with hydration products and unhydrated particles, resulting in the densification of the solidified soils and the cohesion increase of soil particles. The findings confirm the feasibility of substituting Portland cement with titanium slag and flue gas desulfurized gypsum to prepare an effective and environmentally friendly soil solidifier, to reduce the demand for Portland cement in soil solidification.

Exceptional strength and wear resistance in an AA7075/TiB2 composite fabricated via friction consolidation

The friction consolidation method successfully reinforced aluminum 7075 alloy (AA7075) with high-volume fractions (12 and 24 vol%) of titanium diboride (TiB2) by high pressure and severe plastic deformation at elevated temperatures. The consolidated AMCs have a uniform dispersion of submicron- and micron-sized TiB2 particles in the AA7075 matrix, with significant refinement of the matrix grain size and the particles. The addition of TiB2 significantly increases hardness by up to 50 %, Young’s modulus by up to 62 %, and ultimate tensile strength by up to 28 % to 672 MPa, while reducing ductility by 80 %. Wear resistance of 7075/24 vol% TiB2 improves seven-fold compared to baseline, making it comparable to that of carburized steels. Microstructure-based finite element modeling provided a theoretical strength limit of ∼730 MPa for the composites and indicated that high triaxiality in conjunction with severe equivalent plastic strain in a narrow area between the TiB2 particles led to early fracture initiations, limiting the ductility.

Research on the strengthening mechanism of Nb–Ti microalloyed ultra low carbon IF steel

Interstitial free (IF) steels are characterized by their interstitial free ferritic matrix due to addition of micro-alloying elements that draw carbon and nitrogen out of matrix to form carbonitrides. The IF steels typically have excellent deep drawing ability, certain mechanical strength, and high plastic deformation performance. In this paper, the microstructure evolution and carbides precipitation behavior during the hot rolling, cold rolling and annealing processes have been studied using both experimental and thermodynamic and kinetic modeling approaches. The strengthening mechanism of Nb–Ti microalloyed IF steel has been investigated. The results of the thermodynamic simulation indicates that the addition of Nb into Ti bearing IF steel promotes recrystallization at 900 °C, leading to fine recrystallized grains. Due to the recrystallization of austenite during the final rolling process, Nb–Ti microalloyed hot rolled plates exhibit finer grain size, fewer substructures, and lower dislocation density compared to the hot rolled plates containing only Ti. Building upon the initial fine and uniform structure, Nb–Ti microalloyed steel maintains a refined structure after undergoing cold rolling and annealing. The study of the carbides precipitation behavior suggests that TiN precipitates at high temperature above 1100 °C, while a substantial amount of (Nb,Ti)C and TiC precipitate at about 900 °C in Nb–Ti and Ti bearing steels, respectively. There is no significantly difference between the amount of carbides in steels hot deformed at 900 °C and in the hot rolled plates, indicating that the carbides mainly precipitate during the hot rolling process. There are negligible carbides precipitated during the coiling process at 600 °C. In Nb–Ti containing steel, Nb and Ti in solid solution are significantly reduced due to the large amount precipitation of (Nb,Ti)C during the final rolling process. The reduction of solid solution Nb effectively promotes the recrystallization of austenite. Therefore, the grains of hot-rolled, cold-rolled, and annealed strips are refined. In addition, there are more small size carbides in Nb–Ti bearing steel than that in Ti bearing steel. Therefore, the higher strength of Nb–Ti steel is mainly from the strengthening effect of grain refinement and carbides precipitation.

Effect of Welding Gap of Thin Plate Butt Welds on Inherent Strain and Welding Deformation of a Large Complex Box Structure.

In this study, an effective numerical model was developed for the calculation of the deformation of laser-welded 3 mm 304L stainless steel plates with different gaps (0.2 mm, 0.5 mm, and 1.0 mm). The welding deformation would become larger when the welding gaps increased, and the largest deformation values along the Z direction, of 4 mm, were produced when the gap value was 1.0 mm. A larger plastic strain region was generated in the location near the weld seam, since higher plastic deformation had occurred. In addition, the tensile stress model was also applied at the plastic strain zone and demonstrated that a larger welding gap led to a wider residual stress area. Based on the above results, inherent deformations for butt and corner joints were calculated according to inherent strain theory, and the welding formation for the complex structure was calculated with different gaps. The numerical results demonstrated that a larger deformation was also produced with a larger welding gap and that it could reach the highest value of 10.1 mm. This proves that a smaller welding gap should be adopted during the laser welding of complex structures to avoid excessive welding deformation.

The role of the preparation route on microstructure and mechanical properties of AlCoCrFeNi high entropy alloy

Nearly equiatomic AlCoCrFeNi alloy samples were prepared by induction melting and mechanical alloying (MA) combined with spark plasma sintering (SPS). The cast sample showed a dendritic microstructure composed of spinodally decomposed nanometric constituents of the B2 and BCC phases. The spark plasma sintered sample exhibited an ultrafine-grained microstructure of B2 phase and FCC solid solution and Cr23C6 carbides. The MA + SPS sample was strengthened by compressive stress-strain test up to a yield strength of 2029 ± 5 MPa, resulting significantly higher compared to 1366 ± 32 MPa of the cast sample. In addition to the higher compressive yield strength, the sintered sample exhibited a hardness of more than 130 HV higher compared to the cast alloy. On the other hand, the cast alloy showed high plastic deformation (29%) and significantly high ultimate compressive strength of 3072 ± 122 MPa. Together with these mechanical characteristics, the MA + SPS sample showed good thermal stability while preserving the mechanical properties even after annealing at 800 °C. This was not the case with the cast sample, in which ductility and ultimate strength significantly decreased upon annealing at 800 °C. A substantial yield strength reduction of both MA + SPS and cast samples was recorded when tested at 800 °C. Nevertheless, stress-strain curve trends were observed to be quite different between the two samples, thus suggesting dissimilar deformation mechanisms under high-temperature compression.

Phase transformation mechanisms of NiTi shape memory alloy during electromagnetic pulse welding of Al/NiTi dissimilar joints

The phase transformation mechanisms of NiTi shape memory alloy (SMA) during electromagnetic pulse welding (EMPW) of Al/NiTi dissimilar alloy joints were studied. Two types of amorphization behaviors were observed in the NiTi SMA of the Al/NiTi dissimilar joint. These are: i) fast cooling-induced amorphization of the joint interfacial reaction layer; and ii) severe deformation-induced amorphization. Additionally, the martensitic transformation was observed in the NiTi SMA during the high strain rate plastic deformation imposed by the EMPW process. The study shows that the formation of B19' martensite during high strain rate plastic deformation of NiTi SMA is influenced by both the strain rate and the peak pressure of the deformation during welding.

In vitro evaluation of stress corrosion cracking susceptibility of PEO-coated rare-earth magnesium alloy WE43

Controlling material degradation in complex mechanobiological environments is the current challenge in advancing biodegradable magnesium implants for orthopaedic applications. Understanding stress corrosion cracking (SCC) mechanisms of magnesium alloy-coating systems in physiological fluids facilitates the design of magnesium implants with excellent biomedical performance. In this study, we investigated the SCC behaviour of a medical grade PEO-coated magnesium alloy WE43 under different loading conditions. Constant loadings tests (CLT) and slow strain rate tests (SSRT) were conducted to evaluate the SCC susceptibility of this alloy-coating system under in vitro conditions. Fracture surfaces of the non-coated and PEO-coated specimens were characterised by scanning electron microscopy to reveal the SCC mechanisms under different loading configurations. The experimental results showed that the alloy-coating system exhibits a high SCC resistance in SSRT conditions. However, high stress levels and plastic deformations lead to a significant acceleration of the SCC process. Moreover, the fracture surface analysis demonstrated that the brittle nature of the PEO coating deteriorates the mechanical integrity of the alloy under critical mechanical loadings, which results in an increased susceptibility towards stress corrosion cracking of the coated WE43.

Micromechanism and mathematical model of stress sensitivity in tight reservoirs of binary granular medium

Research on reservoir rock stress sensitivity has traditionally focused on unary granular structures, neglecting the binary nature of real reservoirs, especially tight reservoirs. Understanding the stress-sensitive behavior and mathematical characterization of binary granular media remains a challenging task. In this study, we conducted online-NMR experiments to investigate the permeability and porosity evolution as well as stress-sensitive control mechanisms in tight sandy conglomerate samples. The results revealed stress sensitivity coefficients between 0.042 and 0.098 and permeability damage rates ranging from 65.6% to 90.9%, with an average pore compression coefficient of 0.0168–0.0208 MPa−1. Pore-scale compression occurred in three stages: filling, compression, and compaction, with matrix pores playing a dominant role in pore compression. The stress sensitivity of binary granular media was found to be influenced by the support structure and particle properties. High stress sensitivity was associated with small fine particle size, high fines content, high uniformity coefficient of particle size, high plastic deformation, and low Young's modulus. Matrix-supported samples exhibited a high irreversible permeability damage rate (average = 74.2%) and stress sensitivity coefficients (average = 0.089), with pore spaces more slit-like. In contrast, grain-supported samples showed low stress sensitivity coefficients (average = 0.021) at high stress stages. Based on the experiments, we developed a mathematical model for stress sensitivity in binary granular media, considering binary granular properties and nested interactions using Hertz contact deformation and Poiseuille theory. By describing the change in activity content of fines under stress, we characterized the non-stationary state of compressive deformation in the binary granular structure and classified the reservoir into three categories. The model was applied for production prediction using actual data from the Mahu reservoir in China, showing that the energy retention rates of support-dominated, fill-dominated, and matrix-controlled reservoirs should be higher than 70.1%, 88%, and 90.2%, respectively.

Characterization of stress drop and strain localization for titanium alloy subjected to electrically-assisted tension

The stress drop and strain localization behaviors of Ti–6Al–4V titanium alloy under the action of single pulse were investigated using electrically-assisted (EA) tension tests in this study. It is found that the flow stress drop gradually increases with the increase of current density and pulse width during EA tension. The digital image correlation (DIC) technology was adopted to analyze the strain distribution evolution and fracture regulation in EA micro-tension process. It turn out that the EA tensile sample will suddenly form two new intersecting high-strain bands at the moment of applying a pulse. With the increase of strain, the two high-strain bands converge toward the center and gradually evolve into a crossed localized flow zone, which makes the EA tensile sample exhibit a high local plastic deformation compared with room temperature tension. Furthermore, with the increase of current density, the temperature gradient in the tensile direction of the sample increases gradually, resulting in the narrowing of localized flow zone. The transformation of the localized flow zone eventually leads to the increase of fracture angle and the formation of a sawtooth shape fracture morphology. Finally, a material flow model for the single-pulse EA tension process was established. The calculation results show that about 11 % of the stress drop comes from the contribution of non-thermal electroplastic, the main mechanism of stress drop is thermal softening and thermal expansion induced by Joule heat during EA tension.

Microstructure and wear behaviors of 17-4 PH stainless steel fabricated by laser cladding with post laser shock peening treatment

Laser cladding (LC) technology provides an attractive and cost-effective way to prepare wear-resistant coating on high-value engineering components. However, the thermal effect of coating will lead to a large amount of residual tensile stress in the coating, which seriously affects the wear performance. This paper investigated the influence of laser shock peening (LSP) on the microstructure and wear behaviors of wire-based LC 17-4 PH coating. Results showed that there was no laser remelting phenomenon during LSP process, and all residual austenite in cladding layer transformed into martensite after LSP treatment, accompanied by a more compact and uniform microstructure. LSP can introduce severe plastic deformation to form dislocation structures on the top surface of the coating, which lead to grain refinement through dynamic recrystallization (DRX), and the average grain size decreased from 4.15 μm to 1.81 μm when the laser energy is 9J. Meanwhile, the high strain rate plastic deformation induced by LSP generated high residual compressive stress on the material surface, with a maximum value of 500 MPa. The surface microhardness of the cladding layer increased by 100HV after LSP treatment, reaching to a peak of 458HV at a laser power of 9J, and gradually decreased along the depth direction, presenting a gradient distribution. After LSP treatment, GCr15 steel counter ball was used to simulate the sliding friction of solid particles under real working conditions. Results showed that the friction coefficient (COF) and wear rate of 17-4 PH coating were significantly reduced. Furthermore, the wear type changed from dominative adhesive to slight abrasive wear. The improvement of microhardness and wear properties were attributed to the combined effects of Hall-Petch and Taylor hardening strengthening.

EXPERIMENTAL INVESTIGATION OF JOINING THE METAL/POLYMER/METAL COMPOSITE SHEETS BY CLINCHING METHOD

Advances in sandwich composites have given rise to materials that amalgamate the elevated flexural stiffness and buckling resistance found in metals with the lightweight characteristics of polymers. These materials exhibit significant potential for use in contemporary lightweight structures, not solely due to the aforementioned attributes, but also owing to their effective provision of sound, vibration, and thermal protection. In the structures using sandwich materials, joining methods based on fusion welding, adhesive bonding or mechanical fastening are employed. Clinching is a manufacturing technique that mechanically joins two or more materials without the need for heat or additional components. This method relies on achieving high plastic deformation to establish a secure bond. The research deals with the possibility of using the clinching method for joining metal/polymer/metal composite sheets in combination with high-strength steel and micro-alloyed hot-dip galvanised steel sheets. The clinching method with a rigid die proves unsuitable for joining the examined combinations of sandwich material with steel sheets.

Spatially Programmable Architected Materials Inspired by the Metallurgical Phase Engineering.

Programmable architected materials with the capabilities of precisely storing predefined mechanical behaviors and adaptive deformation responses upon external stimulations are desirable to help increase the performance and the organic integration of materials with surrounding environments. Here, a new approach inspired by the physical metallurgical principles is proposed to allow the materials designers to not only enhance the global strength but also precisely tune mechanical properties (such as strength, modulus, and plastic deformation) locally in architected materials to create a new class of intelligent mechanical metamaterials. Such programmable materials not only have high strength and plastic deformation stability but also the ability to regulate the local deformation states and spatially control the internal propagation of deformation. This innovative approach also provides new and effective ways to enhance the adaptivity of the materials thanks to responsive strengths that not only make the materials increasingly stronger but also allow threshold-based adaptive responses to external loading.