Constitutive Equations and Processing Maps for 49MnVS3 Non-Quenched and Tempered Steel

Flow stress variations of 49MnVS3 non-quenched and tempered steel are studied in isothermal compression tests on a Gleeble-1500D thermal simulated test machine at a deformation temperatures of 950, 1000, 1150, and 1200° C, and strain rates of 0.1, 1, 5, and 10 s⁻¹, with obtaining the strain hardening exponent n and deformation activation energy Q of the alloy. Thus, the constitutive equations and processing maps of compression flow behavior for 49MnVS3 non-quenched and tempered steel at high temperatures are established. It shows that the peak stress is shownto significantly reduced with a decrease in the strain rate and increase in deformation temperature when the alloy deforms at high temperature, and the deformation activation energy is 350.98 kJ/mol. When the true strain of 49MnVS3 non-quenched and microalloyed steel high-temperature deformation is 0.5, the optimum process parameters of the alloy are determined to be 1150–1200° C for the deformation temperature and 2–10 s⁻¹ for the strain rate, based on the criterion that the process parameters of higher power dissipation efficiency values should be chosen in the dynamic recrystallization region as the best processing technology.Изменение напряжения течения незакаленной и закаленной стали 49MnVS3 исследовали путем проведения испытаний на изотермическое сжатие на установке Gleeble-1500D, моделирующей высокотемпературные условия, при температурах деформации 950, 1000, 1150, 1200° C и скоростях деформации 0,1; 1; 5 и 10 c⁻¹ с показателем степени деформационного упрочнения n и значением энергии активации деформации сплава Q. Установлены определяющие уравнения и схемы обработки компрессионного режима течения для незакаленной и закаленной стали 49MnVS3 при высокой температуре. Анализ уравнений показал, что максимальное значение напряжения значительно уменьшается при снижении скорости деформации и повышении температуры деформации, если сплав подвергается деформации при высокой температуре, а значение энергии активации деформации составляет 350,98 кДж/моль. Если значения истинной деформации незакаленной стали 49MnVS3 и высокотемпературной деформации микролегированной стали составляют 0,5, то оптимальные параметры процесса обработки сплава определяются при температуре деформирования 1150…1200° C и скорости деформации 2…10 c⁻¹ на основе критерия, который способствует отбору параметров с более высокой эффективностью рассеивания мощности в области динамической рекристаллизации в качестве оптимальной технологии обработки.Зміну напруження течії незагартованої і загартованої сталі 49MnVS3 досліджували шляхом проведення випробувань на ізотермічний стиск на установці Gleeble-1500D, що моделює високотемпературні умови, за температур деформації 950, 1000, 1150, 1200° C та швидкості деформації 0,1; 1; 5 і 10 c⁻¹ із показником степеня деформаційного зміцнення n і значенням енергії активації деформації сплаву Q. Установлено визначальні рівняння і схеми обробки компресійного режиму течії для незагартованої і загартованої сталі 49MnVS3 за високої температури. Аналіз рівнянь показав, що максимальне значення напруження значно зменшується зі зниженням швидкості деформації і підвищенні температури деформації, якщо сплав зазнає деформації за високої температури, а значення енергії активації деформації дорівнює 350,98 кДж/моль. Якщо значення істинної деформації незагартованої сталі 49MnVS3 і високотемпературної деформації мікролегованої сталі дорівнюють 0,5, то оптимальні параметри процесу обробки сплаву визначаються за температури деформування 1150...1200° C і швидкості деформації 2...10 c⁻¹ на основі критерію, який сприяє відбору параметрів із більш високою ефективністю розсіяння потужності в області динамічної рекристалізації як оптимальної технології обробки

Recognizing basal cell carcinoma on smartphone‐captured digital histopathology images with a deep neural network

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154530/1/bjd18026.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154530/2/bjd18026_am.pd

Continuous twin screw rheo-extrusion of an AZ91D magnesium alloy

© The Minerals, Metals & Materials Society and ASM International 2012The twin screw rheo-extrusion (TSRE) is designed to take advantage of the nondendritc microstructure and thixotropic characterization of semisolid-metal slurries and produce simple metal profiles directly from melts. The extrusion equipment consists of a rotor-stator high shear slurry maker, a twin screw extruder, and a die assembly. The process is continuous and has a potential for significantly saving energy, manufacturing cost, and enhancing efficiency. The present investigation was carried out to study the process performance for processing rods of an AZ91D magnesium alloy and the microstructure evolution during processing. The semisolid slurry prepared by the process was characterized by uniformly distributed nondendritic granular primary phase particles. AZ91D rods with uniform and fine microstructures and moderate mechanical properties were produced. For the given slurry making parameters, decreasing extrusion temperature was found to improve microstructures and properties. The mechanisms of particle granulation and refinement and the effect of processing parameters on process performance and thermal management are discussed. © 2012 The Minerals, Metals & Materials Society and ASM International.EPSRC (UK) and Rautomead Lt

Microwave heating, isothermal sintering, and mechanical properties of powder metallurgy titanium and titanium alloys

This article presents a detailed assessment of microwave (MW) heating, isothermal sintering, and the resulting tensile properties of commercially pure Ti (CP-Ti), Ti-6Al-4V, and Ti-10V-2Fe-3Al (wt pct), by comparison with those fabricated by conventional vacuum sintering. The potential of MW sintering for titanium fabrication is evaluated accordingly. Pure MW radiation is capable of heating titanium powder to ≥1573 K (1300 C), but the heating response is erratic and difficult to reproduce. In contrast, the use of SiC MW susceptors ensures rapid, consistent, and controllable MW heating of titanium powder. MW sintering can consolidate CP-Ti and Ti alloys compacted from -100 mesh hydride-dehydride (HDH) Ti powder to ~95.0 pct theoretical density (TD) at 1573 K (1300 C), but no accelerated isothermal sintering has been observed over conventional practice. Significant interstitial contamination occurred from the Al2O3-SiC insulation-susceptor package, despite the high vacuum used (≤4.0 × 10-3 Pa). This leads to erratic mechanical properties including poor tensile ductility. The use of Ti sponge as impurity (O, N, C, and Si) absorbers can effectively eliminate this problem and ensure good-to-excellent tensile properties for MW-sintered CP-Ti, Ti-10V-2Fe-3Al, and Ti-6Al-4V. The mechanisms behind various observations are discussed. The prime benefit of MW sintering of Ti powder is rapid heating. MW sintering of Ti powder is suitable for the fabrication of small titanium parts or titanium preforms for subsequent thermomechanical processing

Measurement of the View the tt production cross-section using eμ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

This paper describes a measurement of the inclusive top quark pair production cross-section (σtt¯) with a data sample of 3.2 fb−1 of proton–proton collisions at a centre-of-mass energy of √s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously σtt¯ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt¯ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented

Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at sqrt [ s ] = 13TeV

A search for physics beyond the Standard Model, in final states with at least one high transverse momentum charged lepton (electron or muon) and two additional high transverse momentum leptons or jets, is performed using 3.2 fb−1 of proton–proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015 at √s = 13 TeV. The upper end of the distribution of the scalar sum of the transverse momenta of leptons and jets is sensitive to the production of high-mass objects. No excess of events beyond Standard Model predictions is observed. Exclusion limits are set for models of microscopic black holes with two to six extra dimensions

The performance of the jet trigger for the ATLAS detector during 2011 data taking

The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction

Search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at sqrt (s) = 13 TeV with the ATLAS detector

A search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 fb−1 of pp collisions at View the MathML sources=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter