Rounded Edges Research Articles

Surfactant – Controlled synthesis of polygonal-stacked Cu2O for morphology effect on lithium-ion battery anode performance

Recently, lithium‐ion batteries have reached the limit of low reversible capacity that is deficient for uses in emerging electric devices for mobiles and electric vehicles (EVs). In this work, we have prepared polygonal-stacked Cu2O (PCO) through modified Benedict's reaction by simply controlling concentrations of cetyltrimethylammonium bromide (CTAB). The synthesized PCO materials featuring sharp tip structure showed enhanced capacity than round edge structured PCO. Surface area and structural difference could play critical roles in the electrochemical performances of the PCO materials. Among three different structured Cu2O materials, sharp tip shaped PCO electrode exhibited a high discharge capacity of ca. 402 mAh/g at the 2nd cycle and its discharge capacity appeared to gradually increase to ca. 506 mAh/g up to the 100th cycle. The diffusion coefficient of sharp tip shaped PCO was also larger than PCO with round-structured morphology. The simple synthesis strategy for the resulting unique electrode morphology can allow to understand morphology effects on anode materials for lithium-ion batteries.

Mean and unsteady loading on square prisms with rounded edges: Hard marine growth, incidence, and Reynolds number effects

A set of wind tunnel experiments was performed to study the average and fluctuating wind loading on an ”infinite” 2D square prism with rounded edges of r/D = 0.16 for different heights of simulated hard marine growth at sub-to transcritical Reynolds numbers. It has already been shown, that a change in surface roughness from ks/D = 4.5×10−6 (smooth) to 1×10−3 (rough) on a similar prism at α = 0° and 45° had large effects on the widths and the Reynolds numbers marking the boundaries of the various flow states. At α = 45° it furthermore led to a large Reynolds-number independency of the lift and drag forces and of the Strouhal number. For the present wind tunnel tests two additional values of ks/D were selected to obtain smaller increments in surface roughness: 4.5×10-4 (slightly rough) and 1.4×10−3 (very rough). Mean and fluctuating lift and drag forces, the main vortex shedding frequency, distributions of the mean surface pressures in the mid-span cross-section of the prism and the mean wake profiles were recorded simultaneously. The same two static angles of incidence, α = 0° and 45°, were investigated for ReD = 60,000–12 million. For the prisms with smooth up to rough surfaces strong effects on the behaviour of all aerodynamic parameters with Reynolds number were found, whereas a further increase in ks/D induced hardly any additional effects. The absolute values of the aerodynamic parameters were found to be independent of a change in ks/D for the sub-to supercritical flow states. For the smooth and slightly rough prisms at α = 0° the supercritical flow state was present up to ReD = 12 million, whereas for the rougher prisms the upper transition and the transcritical flow states appeared at high Reynolds numbers. A change to α = 45° induced little variation with ks/D for all aerodynamic coefficients. The overall behaviour of the force coefficients and the Strouhal number with ks/D and ReD were caused by motions of the transition, separation and reattachment locations.

Impact of Sharp Versus Rounded Edge of Turbulator on Transport Enhancement

Considering the constraints of manufacturing sharp ribs, a systematic study of the aerothermal behavior of the sharp and rounded-edge ribs has been performed. The investigation was conducted in a square channel with 45 deg ribs over a wide range of Reynolds numbers ( to 135,000). The rounded-edge ribs are known to reduce heat transfer and friction compared to the sharp ribs. However, the studies at high blockage ratio show that rounded edges of the ribs have a smaller effect on the heat transfer but the substantial effect on the pressure drop, which is favorable for better cooling effectiveness. This new study with the lower blockage ratio (i.e., 0.0625) rounded-edge ribs offers an interesting insight. The result confirms that at the lower blockage ratio the rounded-edge ribs reduce the heat transfer capacity to a greater extent but have minimal effect on the pressure drop, especially at high Reynolds number. Numerical studies were also conducted using realizable , , and shear stress transport turbulence models. The results are compared with the experimental data to shed light on the prediction capability of these models for both kinds of the ribs at such a wide range of Reynolds numbers. The effect of the rounded-edge ribs on the flow behavior and the consequent impact on the local heat transfer distribution is also studied.

Classifying Crystals of Rounded Tetrahedra and Determining Their Order Parameters Using Dimensionality Reduction.

Using simulations we study the phase behavior of a family of hard spherotetrahedra, a shape that interpolates between tetrahedra and spheres. We identify 13 close-packed structures, some with packings that are significantly denser than previously reported. Twelve of these are crystals with unit cells of N = 2 or N = 4 particles, but in the shape regime of slightly rounded tetrahedra we find that the densest structure is a quasicrystal approximant with a unit cell of N = 82 particles. All 13 structures are also stable below close packing, together with an additional 14th plastic crystal phase at the sphere side of the phase diagram, and upon sufficient dilution to packing fractions below 50–60% all structures melt. Interestingly, however, upon compressing the fluid phase, self-assembly takes place spontaneously only at the tetrahedron and the sphere side of the family but not in an intermediate regime of tetrahedra with rounded edges. We describe the local environment of each particle by a set of l-fold bond orientational order parameters q̅l, which we use in an extensive principal component analysis. We find that the total packing fraction as well as several particular linear combinations of q̅l rather than individual q̅l’s are optimally distinctive, specifically the differences q̅4 – q̅6 for separating tetragonal from hexagonal structures and q̅4–q̅8 for distinguishing tetragonal structures. We argue that these characteristic combinations are also useful as reliable order parameters in nucleation studies, enhanced sampling techniques, or inverse-design methods involving odd-shaped particles in general.

ИССЛЕДОВАНИЕ ТЕХНОЛОГИЧЕСКИХ ПАРАМЕТРОВ РЕШЕТНОЙ УСТАНОВКИ

Annual harvesting of a large number of forest seeds allows for reforestation on the territory of the Russian Federation. Moreover, more than 70% falls on the seeds of coniferous trees. In order to increase their sowing quality and reduce losses, the seeds are dehumidified, cleaned, sorted by density and size, stratification, as well as other technological operations. The use of refined seeds during reforestation allows increasing the productivity of sowing units, improving the quality of seed placement, reducing the volume of seed bins, which leads to a decrease in the metal consumption of sewing machines as a whole. For experimental studies, special sieves were made: plastic with chamfered, plastic with standard holes and plastic with rounded edges. The dependences of the completeness of separation of the procode fraction ε were determined for various combinations of the angle of inclination α and the rotation frequency of the working body ω for various seed thicknesses. The angle of inclination of the working body α was changed from 4 ° to 12 °, in increments of 2 °, rotation frequency ω from 400 min--to 1200 min-¹, in increments of 200 min-¹. The size gap was set taking into account the dimensional characteristics of existing sieves with rectangular holes and was 0.2 mm. Studies were conducted on the seeds of common pine.

Tungsten Oxide Nanoplates: Facile Synthesis, Controllable Oxygen Deficiency and Photocatalytic Activity

Monoclinic tungsten oxide (WO3) nanoplates were synthesized via a two-step simple process: acid precipitation at room temperature to prepare WO3.H2O nanoplates and annealing at high temperature (400 and 500 oC) in ambient air to obtain WO3 nanoplates. The effect of annealing temperature on physical properties (morphology, oxygen deficiency, crystallinity, optical properties, and photocatalytic activity) of WO3 nanoplates was studied. At both two studied annealing temperatures, all samples have the stable monoclinic structure and visible light-range optical bandgap, but the morphology and photocatalytic activity of the samples vary significantly with annealing temperature. At higher annealing temperature (500 oC), the sample has both nanoplate and nanograin morphologies with round edges, higher crystallinity, larger optical bandgap (2.71 eV), and lower photocatalytic activity. The sample annealed at 400 oC has nanoplate morphology with sharp edges, lower optical bandgap (2.63 eV), and higher photocatalytic which shows a high potential for photocatalytic application under visible light irradiation. The effect of the annealing temperature on the properties of WO3 nanoplates is assigned to the dehydration, the coalescence, and/or the melting processes at high temperatures. Dehydration causes the formation of oxygen vacancy – oxygen deficiency. The coalescence and/or the melting result in the changing of morphology and the decrease of the oxygen vacancies. These results imply a simple, cost-effective method to prepare highly oxygen-deficient WO3 nanoplates.

Experimental Research of Technology for Strengthening Reinforced Concrete Columns with Carbon Fibers

Reinforcement of columns (piers) is usually accomplished by increasing cross-section through building-up, injecting reinforcing solutions and external reinforcement. The most and progressive method for strengthening is currently external reinforcement, its essence is to glue high-strength sheets, plates or strips (lamellas) onto structure surface with the help of special adhesives. Scientists pay special attention to theoretical and experimental studies of design solutions for external reinforcement of vertical load-bearing structures. Unfortunately, the results of such studies, for example, influence of technology for execution of works on strengthening efficiency are virtually absent. Therefore, the objective of this paper is to carry out experiments with the purpose to study influence of technological factors on efficiency in strengthening of reinforced concrete structures, which absorb compressive forces. The experimental studies have been made in six series that changed the technology of executed works while using various technological factors. Among the main factors are the following: presence/absence of acute angles; preparation of a base (surface coating); method for gluing reinforcing materials to a structure. A criterion for evaluation of technology efficiency has been breaking strength for axial compression of reinforced samples. Analysis on the results of experimental studies has shown that the highest load-bearing capacity is achieved while using samples of columns with rounded edges, provided that an adhesive is applied to sample base and carbon fiber (40.6 tons). The compressive strength of such samples is by 82.2 % higher than the strength of control samples. The strength of reinforced specimens with non-rounded edges has appeared to be the lowest one, namely 34.0 tons. Strengthening of the samples with fiber impregnated with an adhesive has increased the indicator by 74.3 % compared to the control samples. The compressive strength of samples reinforced with carbon fiber adhered to the adhesive which is preliminary spread on the basis is equal to 38.6 tons, which is by 73.4 % higher than the strength of the control samples.

Influence of Cemented Carbide Composition on Cutting Temperatures and Corresponding Hot Hardnesses.

During metal cutting, high temperatures of several hundred-degree Celsius occur locally at the cutting edge, which greatly impacts tool wear and life. Not only the cutting parameters, but also the tool material’s properties influence the arising cutting temperature which in turn alters the mechanical properties of the tool. In this study, the hardness and thermal conductivity of cemented tungsten carbides were investigated in the range between room temperature and 1000 °C. The occurring temperatures close to the cutting edge were measured with two color pyrometry. The interactions between cemented carbide tool properties and cutting process parameters, including cutting edge rounding, are discussed. The results show that cemented carbides with higher thermal conductivities lead to lower temperatures during cutting. As a result, the effective hardness at the cutting edge can be strongly influenced by the thermal conductivity. The differences in hardness measured at room temperature can be equalized or evened out depending on the combination of hardness and thermal conductivity. This in turn has a direct influence on tool wear. Wear is also influenced by the softening of the workpiece, so that higher cutting temperatures can lead to less wear despite the same effective hardness.

Sensitivity analysis of hybrid methods for the flow around the ahmed body with application to passive control with rounded edges

A comparative study of SST RANS and three hybrid approaches (SAS, DDES and SBES methods) is performed to analyse the flow around the 25∘ Ahmed body. The DDES approach is then selected as the reference model, based on comparison of numerical results. The main study is based on grid and time step influence over the simulation results. All results are compared to in-house experiments. The three grids 15l, 20l and 30l (related to the number of prism layers in the boundary layer) show a fair prediction for both drag Cd and lift Cl coefficients. The best prediction is obtained with the 30l grid with an accurate prediction of Cd and Cl values as well as the main flow characteristics, compared to experiments. Another part of this paper focuses on the time step effect on the computational accuracy. Then, the flow around various rounded edge Ahmed body configurations is compared to experiments in order to validate the robustness of the numerical methodology. The rounded edge flow topologies are therefore deeply investigated. It is shown that they act as passive flow control and significantly influence the flow topology and aerodynamical coefficients. In fact, the rounded strategy modifies the flow detachment and weakens the onset of C-pillar vortices, which directly reduce drag and lift coefficients.

Modeling the kinetics of calcite dissolution in neutral and alkaline solutions

Using kinetic Monte Carlo simulations and scaling approaches, we describe the far from equilibrium calcite dissolution in neutral to alkaline solution and in scales ranging from the molecule detachment from surfaces to that of crystalline grains. The parameters of the thermally activated model are calibrated by the velocities of terrace steps and densities of monolayer pits measured in atomic force microscopy works. The application to nanosized crystalline grains shows that they dissolve at room temperature with significant edge rounding, large rates compared to laboratory estimates, and activation energy equal to that of molecule detachment at kink sites. A different kinetic regime is predicted for grains with typical macroscopic sizes or for high temperatures, in which pit nucleation at flat surfaces and step retreat lead to more uniform dissolution. The extrapolation of high temperature simulation data to room temperature gives dissolution rate 0.3–1.4 μmol/(m2 s) and activation energy 64±3 kJ/mol for macroscopic grains with various densities of surface steps. This rate agrees with the smallest values obtained in a recent compilation of laboratory data in alkaline conditions and the activation energy agrees with laboratory estimates. Grains with high densities of kink sites are shown to dissolve with rates ∼101-102 times larger; these estimates are used to predict the contribution of dislocations and explain the largest values of that compilation.

Stability analysis of block-flexural toppling of rock blocks with round edges

One of the most conventional toppling instabilities is the block-flexural toppling failure that occurs in civil and mining engineering projects. In this kind of failure, some rock columns are broken due to tensile bending stresses, and the others are overturned due to their weights, and finally, all of the blocks topple together. A specific feature of spheroidal weathering is the rounding of the rock column edges. In the mode of flexural toppling failure, rounding of edges happens only at the upper corners of the block but in the block toppling failure mode, due to the presence of cross-joints at the base of the block, rounding of edges also occurs at the base of the block. In this work, a theoretical model is offered to block-flexural toppling failure regarding the erosion phenomenon. The suggested methodology is evaluated through a typical example and a case study. The results of this research work illustrate that in the stable slopes with rectangular prismatic blocks, where the safety factor value is close to one, the slope is subjected to failure due to erosion. Also the results obtained show that the recommended approach is conservative in analyzing the block-flexural toppling failure, and this approach can be applied to evaluate this failure.

Система управления качеством кромки при финишной обработке эластичными полимерно-абразивными инструментами и ее анализ. Часть 1

The purpose of the paper is to create a control system of edge quality under finishing machining of parts by elastic polymer abrasive tools, which are effective in surface conditioning and rounding of part edges. The principle of the system approach is used for a formalized description of the system characterized by the mutual interaction between the subsystems that form it. Consideration is given to the control system of these finishing operations design in order to ensure the required quality (in terms of surface roughness, size and geometric accuracy of edges) and optimal process performance under a large variety of tool designs and shapes of the processed surfaces and their mutual arrangement. The system includes input parameters, state space (subroutines) and output data. The input parameters of the system include equipment, workpiece and tool. The state space includes subsystems of mathematical interaction models of tool and surface and forces on the basis of which the mathematical models of material removal, roughness formation, power consumption, tool wear, and cutting zone temperature operate. The information from these subsystems is transmitted to the subsystem for optimizing finishing operation parameters. An algorithm for designing finishing technological operations is presented. It consists of source data input to the system, analysis of operation functional capability, decisions on the possibility of changes in the input data, control action formation, designing of operation, organization of preparation for operation execution, control of operation execution results for the compliance with the requirements of normative and technical documentation and finishing operation implementation in mass production. The developed system provides optimal tools and processing modes as a result of fulfillment of its functions. When this information is implemented in the manufacturing process of parts, the required quality indicators (surface roughness, size and geometric accuracy of edges) are provided as well as the optimal process performance.

Effect of vacuum pressure on small crack propagation in Ti-6Al-4V

In this study, small crack propagation tests are conducted on artificially defected specimens of Ti-6Al-4V under air and vacuum pressures of 100 Pa, 10−2 Pa, 10−4 Pa, and 10−6 Pa. Fracture surfaces between these environments are compared, and the effect of vacuum pressure on the crack propagation process is investigated. The similarities between surface cracks in vacuum and internal cracks in the very high cycle regime are also discussed from the perspectives of crack propagation rate and fractographic characteristics. From the results, it was observed that there was a tendency for the crack initiation life to increase and the crack propagation rate to decrease with a decrease in the vacuum pressure, although no notable distinction was observed in air and under 100 Pa. The fractography exhibited an angular surface with sharp edges in air and under 100 Pa. However, a granular feature with rounded edges was observed below 10−2 Pa and became more pronounced as the vacuum pressure decreased. The window periods, which formed an oxidized surface coverage, were believed to account for the vacuum effect on crack propagation rate and fracture surface features. Both the crack propagation rate and fractographic features of surface cracks under 10−4–10−6 Pa resembled those of internal cracks; therefore, the presumably working vacuum environment around internal cracks was considered to be at a high vacuum level.

Additive surface texturing of cutting tools using pulsed laser implantation with hard ceramic particles

In recent years surface texturing of the cutting tools has proved to improve tribological characteristics at tool/chip and tool/workpiece interface and help to reduce cutting and feed forces as well as tool wear. Most, if not all, of the studies have focused on subtractively made textures whereby the material is removed from the surface. This study investigates the performance of additively made surface structures whereby hard ceramic particles are dispersed in the form of dome shaped textures on the surface of the cutting tools using solid state millisecond pulsed laser (pulsed laser implantation). Dry cutting tests were performed on ductile cast iron. The results show a greater reduction of process forces with implantation of flank face as compared to rake face. Both cutting and feed forces were reduced by 10% compared to the non-structured tool. In addition, the tool life increased by a factor of 3 whereas the average flank wear reduced by as much as 80% and cutting edge rounding by up to 60%.

The effect of processing parameters and heat-treatment on the microstructure and mechanical properties of PM CoCrFeMnNiTi0.1 high-entropy alloy

CoCrFeMnNiTi0.1 high-entropy alloy (HEA) was fabricated using mechanical alloying (MA) and sintering. To synthesize the HEA, the equiatomic composition of Cr, Co, Fe, Mn, and, Ni powders and Ti powder (1.0. at%) were ball milled at different times and then pressed and sintered specimens were provided. To investigate the effect of heat-treatment on the structure, sintered samples were heat-treated. The powder morphology, microstructure, X-ray diffraction, phase identification, hardness, and compressive strength investigation were performed. The results showed; over time smaller grain size was approached which led to improving the mechanical properties of the HEA. HEA structure contains FCC phase and the disappearance of XRD peaks, intensity decrement, and peak broadening occurred during milling. Heat-treatment led to round edges for the Cr-rich phase due to the decrease in the distance between the lamellar structure. Grain boundary strengthening and precipitation hardening are considered to be the main reinforcement mechanisms due to the addition of Ti. The 20-h heat-treated sample was nominated as the optimum mechanical properties.

Thermal Effect of Surface Catalysis in Subsonic Dissociated-Air Jets. Experiment on a High-Frequency Plasmatron and Numerical Modeling

Experiments on heat transfer in subsonic dissociated-air jets are performed on 100 kW VGU-4 induction plasmatron. The heat fluxes to the water-cooled surfaces of copper, silver, tantalum, beryllium, niobium, gold, molybdenum, and quartz are measured at the stagnation point on a cylindrical flat-nosed model, 50 mm in diameter, having rounded edges at 50 and 100 hPa pressures in the low-pressure chamber and the high-frequency (HF) generator power of 30 to 70 kW. At the same pressures and the HF generator powers of 45 and 64 kW the convective heating of a specimen of sintered silicon carbide is studied in the surface temperature range from 1720 to 1910 K. The predominance of the surface catalyticity effect on the heat flux with respect to nitrogen and oxygen atom recombination is demonstrated. Under the experimental conditions the air plasma flow in the discharge channel of the plasmatron, the subsonic jet flow past the cylindrical model, and the heat transfer to the stagnation point on the model are numerically simulated. Basing on the comparison of the experimental and calculated data on the heat fluxes to the surfaces of metals (Tw = 300 K), quartz (Tw = 572–722 K), and silicon carbide (Tw = 1720–1910 K) the quantitative catalyticity gradation of the materials considered with respect to heterogeneous recombination of nitrogen and oxygen atoms is established.

Pseudophakic Dysphotopsia: Review of Incidence, Cause, and Treatment of Positive and Negative Dysphotopsia

We reviewed the literature concerning positive dysphotopsia (PD) and negative dysphotopsia (ND) regarding cause, incidence, and clinical and surgical management. In addition, we summarized our surgical experience in managing dysphotopsia. A PubMed review, limited to English language articles, yielded 149 citations; multifocal (diffractive optic) and phakic intraocular lens (IOL) dysphotopsia were excluded. Overall, 39 articles were determined to be relevant for the objectives of this investigation. Regarding PD, 7 articles corroborated that the cause of PD is related primarily to internal reflection of oblique light rays that strike the square (truncated) edge of the IOL and are reflected onto the retinal surface. No round-edged foldable IOLs are available in the United States at this time, although IOLs modified with a round anterior edge and square posterior edge show a trend toward decreased incidence of PD. High index of refraction (I/R), surface reflectivity, and IOL optic design are additional causative factors for PD. Regarding the authors' surgical experience, changing the optic material to have a lower I/R improved PD symptoms in the large majority of patients. The cause of ND seems to be multifactorial and less well understood, with some disparity between clinical and laboratory findings. Four articles that explore using ray-tracing optical modeling suggest an "illumination gap," in which some temporally incident light rays to the nasal retina pass anterior to the IOL and some are refracted posteriorly by the IOL, resulting in a gap and resultant temporal shadow. However clinically, ND is associated invariably with well-centered in-the-bag IOLs. Other implicating factors include nasal anterior capsule override, haptic orientation, large-angle κ value, and high hyperopia. Persistent ND has been treated successfully or reduced with reverse (anterior) optic capture, sulcus IOL placement, piggyback IOLs, and neodymium:yttrium-aluminum-garnet nasal capsulectomy. Two articles reference a new optic edge designed to capture the anterior capsulotomy, mimicking reverse optic capture. Persistent dysphotopsia after cataract surgery is a significant cause for patient dissatisfaction. The cause and management of both ND and PD are of significance, and new IOL designs and alternative surgical strategies may help to mitigate these unintended side effects of IOL implantation.

Studies on wear behavior of AlTiN-coated WC tool and machined surface quality in micro endmilling of Inconel 718

The recent developments in science and technology lead to the miniaturization of components in fields like aerospace, biomedical, and electronics. Due to the small tool dimensions and premature tool failure, the tool wear behavior is complicated in micro endmilling of difficult-to-cut materials. In this work, the influence of size effect on wear behavior of AlTiN-coated WC micro endmill and its effects on surface roughness, burr formation, and chip formation during machining on Inconel 718 was studied. It was found that adhesion, delamination, chipping, cutting edge rounding, and flank wear are the significant wear behaviors on AlTiN-coated WC micro endmill during machining of Inconel 718. Workpiece adhesion was observed to be severe in the plowing dominant region. The tool life with 6-μm feed/tooth was found to be 60% more than that with 0.5-μm feed/tooth. The tool failure criteria based on the width of flank wear and cutter edge radius were observed close to 27 and 9 μm, respectively. The feed/tooth adjacent to cutting edge radius was observed as the most favorable cutting condition for good tool life and surface quality.

Pyramidal shaped ceria nano-biointerfaces for studying the early bone cell response

In the last decades, there is an increased interest in developing strategies for improving bio-interfaces in the field of orthopedic or dental implants. Various coating materials were used as nano and micro-structured interfaces to fine-tune the cellular response. Among these, ceria (CeO2) nanostructures are thought to improve the biointerface mechanical properties, but also to stimulate the regenerating tissue biochemical activity by neutralizing the oxidative stress and stimulating cells proliferation. Within this context, this work presents for the first-time pyramid-shaped nanostructured ceria films obtained by Pulsed Laser Deposition (PLD) targeting the early response of human osteosarcoma cells (SaOs-2). SEM and AFM images of the nanostructured surfaces revealed shapes from the quasi-pyramidal, with rounded edges and dimensions of 90–120 nm, to the sharp edges and dimensions up to 350 nm, obtained by varying the number of pulses. The transition from hydrophobic to moderate hydrophilic behavior, as well as the increase of the polar component for the samples with more prominent features, were correlated to the topographical characteristics and further to cell behaviour. The influence of pyramidal-shaped ceria on the in vitro biological performance of SaOs-2 cells was demonstrated by the differences in early adhesion and distribution of phenotype SaOs-2 cells. Nevertheless, as the adhesion and spreading characteristics are cell line specific, mesenchymal stem cells (MSCs) were used for comparing the different cytoskeleton response as response to the ceria nanostructure type. In perspective, the behavior of mesenchymal progenitor cells is foreseen to be analyzed in view of establishing an osteogenic response on these biomaterials and the best-suited processing approach in order to use them as substrates for future bone regeneration applications.

How hair deforms steel

Steels for sharp edges or tools typically have martensitic microstructures, high carbide contents, and various coatings to exhibit high hardness and wear resistance. Yet they become practically unusable upon cutting much softer materials such as human hair, cheese, or potatoes. Despite this being an everyday observation, the underlying physical micromechanisms are poorly understood because of the structural complexity of the interacting materials and the complex boundary conditions of their co-deformation. To unravel this complexity, we carried out interrupted tests and in situ electron microscopy cutting experiments with two micromechanical testing setups. We investigated the findings analytically and numerically, revealing that the spatial variation of lath martensite structure plays the key role leading to a mixed-mode II-III cracking phenomenon before appreciable wear.