Torn Edge Research Articles

Effect of an Ultrasonic Vibration on the Microstructure and Properties of Al Alloy/Steel Laser Welding-Brazing Joints

This study analyzes the influence of different ultrasonic amplitudes on the microstructure composition, microhardness, tensile strength, and corrosion resistance of Al alloy/steel laser welding-brazing joints assisted by ultrasonic vibration. The application of ultrasonic vibration did not change the microstructure composition of the joints but refined them. The joints were all composed of θ-Fe(Al, Si)3 and τ5-Al7.2Fe1.8Si formed at the interface reaction zone, as well as an α-Al solid solution and Al-Si eutectic phase generated in the weld seam zone. Meanwhile, the thickness of the IMCs at the interface decreased with an increase in the ultrasonic amplitude. When the ultrasonic amplitude was 8 μm, the IMCs thickness was a minimum of 1.62 μm. In this condition, the reduction of the IMCs thickness and the refined grain of joints made the microhardness and tensile strength reach the maximum. The fracture of joints with ultrasonic amplitudes of 0 and 4.8 μm began at the weld seam and extended to the interface reaction zone at the steel side, while the fracture of joints was located in the heat-affected zone (HAZ) of the Al alloy side when the ultrasonic amplitude was 8.0 and 11.2 μm. The fracture mode of the former presented a typical mixed fracture with cleavage steps and tearing edges, and that of the latter showed ductile fracture with uniform and fine ductile dimples. The corrosion resistance of the joints was improved by adding ultrasonic vibration. When the ultrasonic amplitude was 8 μm, its corrosion resistance was optimum; it was ascribed to a dense oxide film formed on the surface of the metal under the action of ultrasonic vibration.

Creep properties of heat-resistant ultrafine-grained Al (HITEMAL©) determined by small punch testing

The creep properties of thermally stable ultrafine-grained Al metal matrix composite strengthened and stabilized by continuous in situ amorphous Al2O3 network (named HITEMAL©) prepared by powder metallurgy (PM) were tested by small punch creep testing (SPCT) in the temperature range from 573 to 673 K. The experimental SPCT results were correlated and compared with the results obtained by conventional tensile creep testing. The mutual correlation between tensile and SPCT creep results based on the transition stress was proposed and used to correctly interpret the measured SPCT data. The creep behaviour of HITEMAL© is characterized by the high values of apparent stress exponents and by the presence of transition stress at which the apparent stress exponents significantly changed. The SPCT discs fractured by the radial cracks at low values of deflection with only limited creep deformation highly localized in the vicinity of the fracture surfaces. The detailed analysis of fractured SPCT discs by scanning electron microscopy showed ductile dimpled fracture surfaces with the presence of unusual high filament-like tearing edges. The comparison of obtained results with other PM Al-based alloys and composites confirmed a significantly higher creep performance of HITEMAL© at used testing conditions.

Microstructure evolution and fatigue crack propagation of AlCoCrFeNi2.1 high entropy alloy after electron beam surface modification

AlCoCrFeNi2.1 eutectic high-entropy alloy has good fatigue properties. However, its application in engineering is hindered by as-cast defects. To solve this problem, vacuum electron-beam surface modification is used to strengthen the surface of as-cast high-entropy alloy. It has been discovered that the remelting zone is still composed of body-centered cubic and face-centered cubic phases and that its phase size is refined. A surface-modified structure consisting of the compact RZ and a heat affect zone is obtained, by applying the same fatigue load to the samples before and after electron-beam, respectively. The fatigue crack growth rate of the electron-beam surface-modified material is slower and its life to fracture is longer. Additionally, the fan-shaped fracture and tear edges are typical fracture characteristics of the specimens before and after modification. The results show that with a significant reduction in phase size, the phase boundary density increases. The enhancement of the high-angle grain boundary content and changes in the stress state are also critical factors for the inhibition of fatigue crack growth rate.

Torn Edges: Punk, Art, Design, History, organized by Russ Bestley, London College of Communication, London, 20 March 2024

Review of: Torn Edges: Punk, Art, Design, History, organized by Russ Bestley, London College of Communication, London, 20 March 2024

Experimental Study and Creep-Fatigue Life Prediction of Turbine Blade Material DZ125 Considering the Nonholding Effect and Coupling Effect of Stress and High Temperature

Abstract In response to the problem of creep-fatigue interaction damage failure of aero-engine turbine blade material, based on the modified damage evolution model of Kachanov-Rabotnov and Chaboche, a creep-fatigue life prediction model for nickel-based superalloy DZ125 is constructed considering the nonholding effect and coupling effect of stress and high temperature with the nonlinear interaction and superposition of creep damage and fatigue damage according to the continuum damage mechanics theory. Simultaneously, the microfracture morphology of DZ125 was analyzed using a scanning electron microscope, revealing the micromechanism of creep-fatigue interaction. The research results manifest that the creep-fatigue life prediction model has a high life prediction ability within ±2.0 times the dispersion band of the prediction results. Concurrently, a large number of intertwined tearing edges, microcracks, and microvoids appear in the fracture morphology, and creep and fatigue interact with each other in the form of effective stress. The above research can provide theoretical support for predicting the lifespan of mechanical structures in a high-temperature environment.

Laser Weld Seam Curved Path Effect on 6063 Aluminum Alloy Strength and Temperature Distributions: COMSOL Numerical Simulation

To improve the welding performance of aluminum alloys, a thermal source model of an irregular weld seam was established. COMSOL software was used for numerical simulation of the weld seam geometry effect on the temperature and stress fields in laser welding, which results were experimentally validated. The results show that the ellipsoidal laser welding melted micropool exhibited quasi-steady-state temperature field characteristics. The temperature gradient and thermal stress showed an increase followed by a decline. The temperature fluctuation amplitude of the square-tooth-shaped weld seam exceeded that of the arc-toothshaped one. The temperature evolution of the broken line tooth-shaped weld seam showed a slightly increasing trend, except for the inflection point. The experimental average tensile strength of the weld seam was the highest, reaching about 210 MPa, i.e., roughly 85% of the base material (245 MPa), which coincided with the COMSOL-based temperature field simulation results. With increasing deformation amplitude and transition radius, the maximum tensile force, tensile strength, and elongation at fracture showed an increasing trend. However, the deformation amplitude should be below a certain limit because its increase elongates the welding path and reduces the distance between weld seams, resulting in serious heat accumulation. The tensile fracture morphology of the 6063-T6 base material was curved shear, with shallow toughness pits, small tearing edges at the edges, and small granular objects, indicating small plastic deformation during the fracture process. The tensile fracture of the welded part spanned the weld seam and the base material, and the fracture occurred along the tangent direction of the weld seam. The fracture surface was smooth, the tearing edges at the edge of the toughness pit shifted along the weld seam direction, forming many co-directional slip bands, with highly pronounced plastic deformation.

The Effect of Addition Amount of Chromium Iron on the Bonding Strength between Alloy Steel Surfacing Layer and Steel Base Metal

Fe-C-Cr-Nb alloy steel surfacing layers with different contents of C and Cr were prepared on 45 steel base metal by selfshielded flux-cored wires with distinct amounts of high carbon chromium iron addition and melt arc surfacing. The composition and microstructure changes of the surfacing layer were tested and analyzed. The surfacing test plate was processed into a pulling specimen, and the bonding strength between the surfacing layer and the 45 steel base metal was tested with a self-designed pulling test method. The fracture location of the pulling specimen and fracture characteristics were observed by a metallurgical microscope and a scanning electron microscope. The result shows that with the increase of the amount of high carbon chromium iron added to flux-cored welding wire, the content of C and Cr in the surfacing layer increases, and the NbC hard phase disperses. The microstructure of the steel matrix changes from mixed martensite + residual austenite to high carbon martensite + residual austenite, and then independent austenite appears. The hardness of the surfacing layer first increases and then decreases. The bonding strength between the surfacing alloy and the 45 steel base metal first decreases and then increases, and the fracture location is at the bottom of the surfacing layer or the fusion zone with mostly quasi-cleavage characteristics. When the additional amount of high carbon chromium iron reaches 13%, thee pulling specimen exhibits significant deformation with the highest bonding strength, and the fracture is close to the fusion line, where there are numerous tearing edges and shallow dimples.

Intimomedial tears of the aorta heal by smooth muscle cell-mediated fibrosis without atherosclerosis.

BACKGROUNDDisease of the aorta varies from atherosclerosis to aneurysms, with complications including rupture, dissection, and poorly characterized limited tears. We studied limited tears without any mural hematoma, termed intimomedial tears, to gain insight into aortic vulnerability to excessive wall stresses. Our premise is that minimal injuries in aortas with sufficient medial resilience to prevent tear progression correspond to initial mechanisms leading to complete structural failure in aortas with significantly compromised medial resilience.METHODSIntimomedial tears were macroscopically identified in 9 of 108 ascending aortas after surgery and analyzed by histology and immunofluorescence confocal microscopy.RESULTSNonhemorrhagic, nonatheromatous tears correlated with advanced aneurysmal disease and most lacked distinctive symptoms or radiological signs. Tears traversed the intima and part of the subjacent media, while the resultant defects were partially or completely filled with neointima characterized by differentiated smooth muscle cells, scattered leukocytes, dense fibrosis, and absent elastic laminae despite tropoelastin synthesis. Healed lesions contained organized fibrin at tear edges without evidence of plasma and erythrocyte extravasation or lipid accumulation.CONCLUSIONThese findings suggest a multiphasic model of aortic wall failure in which primary lesions of intimomedial tears either heal if the media is sufficiently resilient or progress as dissection or rupture by medial delamination and tear completion, respectively. Moreover, mural incorporation of thrombus and cellular responses to injury, two historically important concepts in atheroma pathogenesis, contribute to vessel wall repair with adequate conduit function, but even together are not sufficient to induce atherosclerosis.FUNDINGNIH (R01-HL146723, R01-HL168473) and Yale Department of Surgery.

Effect of Vanadium Addition on Solidification Microstructure and Mechanical Properties of Al-4Ni Alloy.

The effects of vanadium addition on the solidification microstructure and mechanical properties of Al-4Ni alloy were investigated via thermodynamic computation, thermal analysis, microstructural observations, and mechanical properties testing. The results show that the nucleation temperature of primary α-Al increased with increased vanadium addition. A transition from columnar to equiaxed growth took place when adding vanadium to Al-4Ni alloys, and the average grain size of primary α-Al was reduced from 1105 μm to 252 μm. When the vanadium addition was 0.2 wt%, the eutectic nucleation temperature increased from 636.2 °C for the Al-4Ni alloy to 640.5 °C, and the eutectic solidification time decreased from 310 s to 282 s. The average diameter of the eutectic Al3Ni phases in the Al-4Ni-0.2V alloy reduced to 0.14 μm from 0.26 μm for the Al-4Ni alloy. As the vanadium additions exceeded 0.2 wt%, the eutectic nucleation temperature had no obvious change and the eutectic solidification time increased. The eutectic Al3Ni phases began to coarsen, and the number of lamellar eutectic boundaries increased. The mechanical properties of Al-4Ni alloys gradually increased with vanadium addition (0-0.4 wt%). The Al-4Ni-0.4V alloy obtained the maximum tensile strength and elongation values, which were 136.4 MPa and 23.5%, respectively. As the vanadium addition exceeded 0.4 wt%, the strength and elongation decreased, while the hardness continued to increase. Fracture in the Al-4Ni-0.4V alloy exhibited ductile fracture, while fracture in the Al-4Ni-0.6V alloy was composed of dimples, tear edges, and cleavage planes, demonstrating mixed ductile-brittle fracture. The cleavage planes were caused by the primary Al10V and coarse Al3Ni phases at the boundary of eutectic cells.

Synergistic mechanism of strengthening and toughening of tissue regulation response to Mg/Al composite laminates by hard plate accumulative roll bonding

The significance of light alloy in realizing the national strategy of energy saving and emission reduction and promoting the upgrading of the manufacturing industry is self-evident. Mg/Al composite laminates combine the lightweight of magnesium alloy and the plasticity and corrosion resistance of aluminum alloy. Traditional accumulative roll bonding technology relies on the advantage of introducing large deformation. Although high strength is obtained, it is often accompanied by a large loss of ductility, and there is a problem that it is difficult to balance strength and ductility. To solve this problem and optimize the process conditions, a new hard-plate accumulative roll bonding process is proposed in this paper, which is used to prepare high-performance Mg/Al composite plates, and the influence of forming temperature on the microstructure and mechanical properties of Mg matrix is studied. The results show that when the forming temperature is 350 °C, the properties of composite laminates are the best, the tensile strength can reach 243 MPa, the elongation is 14.7 %, and there are a lot of tearing edges and dimples on the fracture surface. At the same time, complete recrystallization can be realized at this temperature, and the opening of non-base slip can coordinate deformation stress, promote the dislocation slip, and reduce the dislocation density, SEM images show that there are no defects such as delamination at the interface, and a firm metallurgical bonding is achieved. It provides a new approach to the forming and manufacturing of high-quality lightweight heterogeneous composite laminates.

Влияние исходных структурных нарушений и послеоперационного изменения перфузии на функциональное восстановление сетчатки после хирургического лечения сквозных макулярных разрывов

Purpose. To evaluate effect of preoperative local structural retinal changes and capillary perfusion in idiopathic full-thickness macular holes (FTMH) on the recovery of functional activity of the retina after surgical treatment. Materials and methods. We used optical coherence tomography (OCT) and OCT-angiography (OCT-A), microperimetry, multifocal electroretinography. In 25 eyes with FTMH the density of capillaries in the superficial and deep capillary plexus (SCP and DCP), retinal sensitivity (RS), amplitude and implicit time of P1 were studied at 13 points located at different distances from the fixation point were evaluated. Data were analyzed in the projection of the hole, intraretinal cystic changes (ICC), neuroepithelial detachment (NED) and intact retina before surgical treatment, 7 days, and 3 months after. Results. In the area of hole, ICC, and NED, in comparison with intact areas of the retina, a significant decrease in RS, an increase in implicit time and a decrease in amplitude of P1, and a decrease in capillary density in the SCP and DCP were revealed. Functional restoration of the retina with an increase in its perfusion was noted 3 months after the surgery. The correlation was found between postoperative changes in RS and changes in capillary density in the SCP in the projection of NED (R=0.32, p=0.001) and ICC (R=0.19, p=0.001), as well as in the DCP in the projection of NED and ICC (R=0.31, p=0.001). The change in the amplitude P1 in the postoperative period significantly correlated with the change in perfusion in the SCP in the projection of the NED (R=0.38, p=0.001) and the hole area (R=0.31, p=0.001), as well as in the DCP in the projection of the ICC (R=0.31, p=0.01) and in the area of NED (R=0.28, p=0.001). Conclusion. Thus, when using a multimodal topographically oriented approach, a relationship was found in the postoperative period of changes in functional parameters at various points in the macular area with changes in local perfusion at the level of both SCP and DCP, while the relationship is most significant in the projection of NED along the tear edge and in the areas of ICC. Key words: full-thickness macular hole (FTMH), microperimetry, multifocal electroretinography, multimodal imaging, optical coherence tomography, optical coherence tomography-angiography

Microstructure and mechanical properties of T2 copper /316L stainless steel explosive welding composite with small size wavy interface

Copper/stainless steel composite is often used for preparation of superconducting busbar “double box” lap joints. However, it is a challenge for the large thickness T2 copper/316L stainless steel composite is fabricated by explosive welding, because of the bonding interface is always present many problems such as large ripple size, many microscopic defects, low bonding strength and poor sealing etc. In this paper, the big-thickness T2 copper/316L stainless steel composite with small size wavy interface was successfully fabricated by explosive welding. Microstructure of bonding interface indicated that the welding process could be divided into three stages: detonation growth stage, detonation stabilization stage, detonation descent stage. The morphology of bonding interface presented a regular wavy interface and no defects such as cracks, voids and intermetallic compound were formed in the stable stage, which was consistent with the results of ultrasonic and permeability quality inspection. The hardness of copper side and stainless steel side close to the bonding interface reached 131HV and 432HV, respectively. Dynamic recrystallization and fine grain generated in the bonding interface. The mechanical properties of tensile strength, pull-off strength and shear strength in the stable detonation stage is greater than 110 MPa, which is meeting the requirements of preparation of superconducting busbar “double box” lap joints. The deformation failure mainly occurred in the copper side near the bonding interface, which presented a higher bonding strength than copper. Some dimples and tearing edges with different sizes on the fracture surfaces, indicating that the fracture was a typical ductile fracture.

IMAGING RHEGMATOGENOUS RETINAL LESIONS AND PERIPHERAL VITREORETINAL INTERFACE WITH WIDEFIELD OPTICAL COHERENCE TOMOGRAPHY.

Analyze the peripheral vitreoretinal interface with widefield optical coherence tomography. Retrospective chart analysis and widefield optical coherence tomography in 120 consecutive cases of rhegmatogenous pathology. There were 166 lesions in 120 eyes, including 106 horseshoe tears, 22 operculated holes, 30 nonoperculated holes, six giant tears, and two peripheral lamellar defects followed for 6.1 ± 1.2 months. Posterior vitreous detachment was present in all eyes (101/101, 100%) with tears and operculated holes, but only in 5/19 eyes (26.3%) with nonoperculated holes ( P < 0.001). Axial vitreous traction was evident at the anterior edge of horseshoe tears (106/106, 100%), but not the posterior border (18/106, 17%, P < 0.001). Operculated holes located posterior to the vitreous base were free from vitreous traction, displaying a morphology similar to the macular hole. Nonoperculated holes were farther anterior with signs of tangential traction in 23/30 (76.7%) cases. Peripheral vitreoschisis was more often associated with nonoperculated holes (25/30, 83.3%), than horseshoe tears (17/106, 16%; P < 0.001). Horseshoe tears and nonoperculated holes were more often associated with retinal detachment (58/106 [54.7%] and 15/30 [50%], respectively) than operculated holes (5/22, 22.7%), P = 0.023. Peripheral vitreoretinal interactions are similar to vitreomaculopathies, with axial and vitreoschisis-related tangential traction playing different roles in different rhegmatogenous pathologies. Peripheral optical coherence tomography improves understanding of pathophysiology and risks of retinal detachment.

Study on creep-fatigue interaction mechanism and life prediction of aero-engine turbine blade

Aiming at the creep-fatigue interaction damage failure problem of turbine blades in aeronautical engineering, firstly, based on the modified Kachanov-Rabotnov-Chaboche (MKRC) damage mechanics theory, the creep-fatigue life prediction model of turbine blade material was constructed with the experimental verification completion of nickel-based superalloy DZ125. Meanwhile, the creep-fatigue interaction behavior was investigated with the mechanism revelation. Then, considering the shape, size and microscopic defect difference effect from the material to the structure, the creep-fatigue life prediction model of turbine blade structure is proposed by introducing the comprehensive correction factor with experimental verification. Finally, the research results show that there are a large number of interwoven tear edges, micro-cracks and micro-pores in the fracture morphology, and creep and fatigue interact with each other in the form of effective stress. Simultaneously, the creep-fatigue life prediction model has a high life prediction ability with an error of 3%, which can provide a theoretical reference for the damage tolerance design of the turbine blade.

Robust OCR Pipeline for Automated Digitization of Mother and Child Protection Cards in India

The Universal Immunization Programme in India has a mandate to fully vaccinate all of India’s 27 million children born annually. The vaccination doses are recorded by frontline health workers on standardized paper-based Mother and Child Protection (MCP) cards, which are manually digitized by data entry operators, resulting in poor data quality, delays, and significant time and resources. In our article, we focus on Optical Character Recognition– (OCR) based automated digitization of MCP card images captured through a smartphone application developed by us. By utilizing a standardized template for the MCP cards, which is available a priori , we register the card images and perform OCR on the extracted region of interest (ROIs). Since the cards with curvature or torn edges had poor ROIs, we built a global–local alignment technique that first approximates the ROI using global homography and then refines using a local homography resulting in improved accuracy. Our pipeline gives a character level accuracy of 98.73% on our dataset against 75.02% by Google Cloud Vision and 79.26% by Azure OCR. We also describe our field testing experience, where the digitized MCP card images were used to provide useful features on the smartphone application for health workers to conduct vaccination sessions.

Microstructure characterization and tensile performance of a high-strength titanium alloy with in-situ precipitates of Ti5Si3

Near β titanium alloys with excellent properties are increasingly preferred for aerospace structural applications, among which the alloys with in-situ precipitated silicides are especially intriguing. Here in this work, based on the low-density, high strength and comparable thermal expansion coefficient to titanium of Ti5Si3, a novel high-strength titanium alloy with in-situ Ti5Si3 precipitate has been developed and further heat treated to regulate the microstructure and properties. The results revealed that the in-situ precipitates including both the needle-shaped secondary α-Ti in the β-Ti matrix and the spherical Ti5Si3 in proximity of α/β phase boundaries contributed to the superior strength and ductility for the alloy after the optimal heat treatment at 800 °C for 40 min. Specifically, it exhibited an ultimate strength of 944.1 MPa and an elongation value of 12.5% with excellent work hardening behavior and ductile fractography including abundant tear edges and dimples. This work validated the strategy of introducing in-situ titanium silicides to stabilize the microstructure and enhance work hardening for developing novel titanium alloys with adjustable and superior properties.

Microstructure and properties of a YG18/40Cr joint vacuum–brazed by Cu–Sn–Ti filler metal

In this study, dissimilar YG18/40Cr joints were prepared using a Cu–Sn–Ti filled metal by a vacuum brazing process, and the microstructural evolution and bonding mechanism of the YG18/Cu–Sn–Ti/40Cr joints were studied. By adjusting the brazing parameters, the formation process of interface structure, the joint structure and matrix internal structure, and the changes in the joint microstructure and properties under different parameters were systematically analyzed. A TiC reaction layer was formed at the interface on both sides of the joint. The brazing performance can be improved by the formation of a reasonable size reaction layer. A TiC–WC cemented carbide was formed near the middle layer inside YG18, and this tenon–and–tenon structure improved the bonding between the YG18 side and the filler alloy. The connector structure was YG18/TiC/CoTi + Co2SnTi/Cu [s, s]/eutectic structure (Cu [s, s] + Cu Sn3Ti5)/CuSn3Ti5/TiC/40Cr, and its eutectic structure changed as the parameters changed. The maximum average shear strength of the YG18/40Cr joint brazed at 940 °C for 5 min reached 216 MPa, which was ≈25% higher than the joint shear strength of the pure copper used in a previous study. The fracture morphology of the joint showed a large number of fossae and tear edges, indicating ductile fracture.

Evolution of in-plane stresses induced fracture behaviors of Tailor Welded Blanks subjected to non-uniformly distributed load

Due to remarkable difference in material properties of Tailor Welded Blanks (TWBs), when subjected to uniform forming load, severe non-uniform metal flow and strain localization occur on TWBs’ “weaker” side, which accelerates the forming failure. In this work, non-uniformly distributed normal pressure generated by heterogeneous elastomer was used to balance the deformation on SS304/SS316 stainless steel TWBs’ two sides. Effects of load patterns (i.e., uniformly and non-uniformly distributed load) on strain distribution, stress states, and fracture morphology of TWBs were studied to clarify the change of failure mechanism based on bulge tests and analytical analysis. The results showed that, when subjected to non-uniformly distributed load, with the ratio of Young’s modulus (φ) of heterogeneous elastomers increasing from 1 to 5.33, normal pressure on the “weaker” side of TWBs (i.e., SS304 side) decreased from 8.68 MPa to 4.34 MPa while that on the “stronger” side (i.e., SS316 side) remained constant. The corresponding radial and circumferential stresses on the “weaker” side decreased by 34.76 MPa and 21.08 MPa, respectively. Excessive plastic deformation on the “weaker” side was decreased and deformation uniformity on both sides was improved. Meanwhile, in the microscopic scale, fracture morphology of materials on the “weaker” and “stronger” sides changed from fracture mode I (i.e., dimples combined with tearing edges) to fracture mode Ⅱ (i.e., two sizes of dimples). Dimples in fracture mode Ⅱ showed similar sizes with these on fractured SS304 and SS316 tensile specimens after uniaxial loading, which implied sufficient plastic deformation on both sides of TWBs.

Increasing the Metal Heating Efficiency in High-Temperature Units

This research paper delves into the improvement of the thermal modes of metal heating in the heating wells and it evaluates the metal heating modes in high-temperature units that affect the quality of products. Consideration was given to the main factors that affect the production cost, namely, slag consumption and conventional fuel consumption at different heating temperatures and metal holding times. The described calculations can be used in industry to improve the production process and reduce the cost of production. The research topic relating to metal heating modes in heating wells is relevant in the context of increasing the efficiency of the production of metal products and reducing production costs. The main problem is the instability of thermal processes in heating wells under variable technological regimes. The purpose of this study was to improve the thermal modes of metal heating in heating wells in order to increase production efficiency and reduce costs. The effect of the technological process delays on thermal processes in heating wells has been studied. To analyze thermal processes in heating wells, a calculation method was used that enabled the assessment of the effect of the changed technological regimes on metal heating indices. The calculation of the thickness of the burning-out crust can be used to preemptively control the metal heating process and prevent the dissection and oxidation of sub-crustal gas bubbles. It will help avoid the formation of such defects as the torn edge and reduce the amount of melted metal, as well as reduce the consumption of slagged metal. The obtained results can be used in the production of metal articles for further research to improve the technological regimes of metal heating in heating wells, in particular, to take into account the influence of other factors on thermal processes and to study the possibilities of using the latest technologies to increase the efficiency and competitiveness of production.

Arthroscopic Meniscus Ramp Repair: The Shoelace Technique

Background: A “ramp lesion” is described as an injury involving the peripheral attachment of the posterior horn of the medial meniscus. Ramp lesions are associated with increased loads on anterior cruciate ligament and leads to rotatory instability of knee. During anterior cruciate ligament reconstruction, failure to identify and treat ramp lesion leads to increased forces on the reconstructed graft and residual instability which ultimately increases chances for graft failure. It is important to identify the ramp lesions by looking at the posterior compartment and repair ramp lesion. Ramp lesions are still a challenge to treat due to misdiagnosis and long learning curve of current techniques. In this technique, we are presenting margin convergence shoelace technique to repair a large ramp lesion. Indications: Isolated ramp lesions or ramp lesions associated with other ligamentous injuries. Technique Description: Through standard anteromedial and anterolateral portals, diagnostic arthroscopy is done. Using Gillquist maneuver, posteromedial compartment is visualized to look for ramp lesion. Probing is done with 18-gauge spinal needle from posteromedial aspect of knee to look for hidden lesions and extent of tear. We use 2 additional portals, low and high posteromedial portals for ramp repair. Visualizing from anterolateral portal entry is made in the posteromedial compartment; low posteromedial portal is created at the level of meniscus; 8-mm passport cannula is inserted and used as working portal; and then, high posteromedial portal is created and used as viewing portal. Visualizing through high posteromedial portal rasping of ramp lesion is done. Now with knee scorpion loaded with 2-0 fiber wire, bites are taken along posterior margin of meniscus and capsular portion of tear edges alternatively in shoelace manner from lateral to medial. Finally, compression and knot tying are done and secured with multiple half hitches. Results: Surgical repair of ramp lesions is associated with good healing, and it restores stability of knee. Follow-up of more than 2 years shows better functional outcome and reduced retear rates. Discussion/Conclusion: Currently, there are a lot of techniques described for ramp repair. We present arthroscopic ramp repair with dual posteromedial portals by shoelace technique, which is a safe, easy, and cost-effective method and gives excellent results and good healing especially in larger tears. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.