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1

Microalloying of Continuous Cast Aluminum Strip and Structural Modification Using Plastic Treatment to a 9 μm Foil (Patent no. 39762, P-377/76)

Purenović M. M., Purenović Jelena M., Baralić J. Č.

Archives of Metallurgy and Materials

|

2023

|

Vol. 68, iss. 1

345--357

EN

Innovative procedure of microalloying continuous cast aluminum strip, thickness 10 mm, by Be, Zr and Mn using 3C Pechiney technology (no. 39762, P-377/76), and modifying the existing parameters for strip casting and crystallization was implemented under industrial conditions with two randomly selected batches 2×8 tones, without previous selection of standardized quality of aluminum, purity Al 99.5%, obtained by electrolysis. The application of microalloying and overall structural modification of the technology resulted in obtaining nanoscale, ultra-thin, compact oxide high-gloss film with uniform surface of continuous cast strip, instead of the usual thick and porous oxide film. The outcome of microalloying the obtained equiaxed fine-grained nano/micro structure was avoiding anisotropic and dendritic microstructure of the strip, and improving deformation and plastic properties of modified continuous cast strip subjected to the technology of plastic treatment by rolling until the desired foil thickness of 9 μm was obtained. The invention of microalloying and structural modification, including multiplying effect of several components, directly or indirectly, changed numerous structurally-sensitive properties. The obtained nano/micro structure of crystal grains with equiaxed structure resulted in the synergy of undesirable <111> and inevitable <100> and <110> textures. Numerous properties were significantly enhanced: elastic modulus was improved, and intensive presence of cracks in warm forming condition was prevented due to rapid increase of the number of grains to 10000 grains/cm2 in as-cast state.

2

The Correlation between Solidification Rates, Microstructure Integrity and Tensile Plastic Behaviour in 4.2 wt.% Silicon Strengthened Ductile Iron

Angella Giuliano, Taloni Marcello, Donnini Riccardo, Zanardi Franco

Journal of Casting & Materials Engineering

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2022

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Vol. 6, no. 1

1--7

EN

High Silicon Strengthened Ductile Iron (HSiSDI) with 4.2 wt.% of silicon was produced in Y-blocks with different thicknesses to investigate the effects of the solidification rate on microstructure integrity and tensile mechanical properties. With decreasing solidification rates, the graphite degeneracy with the appearance of chunky graphite became more significant at the highest silicon contents, so chemical ordering and graphite degeneracy seemed to be qualitative explanations of tensile property degradation. However, a deeper analysis of the relationship between solidification rate, microstructure and tensile properties was realized through an innovative approach based on the Matrix Assessment Diagram (MAD), where the parameters of Voce equation resulting from best-fitting the experimental tensile flow curves of a significant number of HSiSDI samples, were plotted. For 3.5 wt.% silicon content, the MAD analysis indicated that the microstructure was sound for any solidification rate, while for 4.5 wt.% the microstructure was sound only for the fastest solidification rates. For 4.2 wt.% silicon content the MAD analysis pointed out that the tensile plastic behaviour and the microstructure integrity was in between the 3.5 and 4.5 wt.% silicon contents, representing a composition threshold where the reliable microstructures were only found with the fastest solidification rates, while considerable variability was found for the slowest ones. Support to the MAD analysis results was given from microstructure observations.

3

Ductility and formability of Al-Mn ultrafine-grained plates processed by incremental equal channel angular pressing

Ciemiorek Marta, Goliński Jacek, Majchrowicz Kamil, Lewandowska Małgorzata

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e169, 2022

EN

The article discusses the ductility and formability of ultrafine-grained 3003 aluminum alloy plates processed using incremental equal channel angular pressing. The influence of temperature and strain rate is evaluated by means of tensile tests and cupping tests under various conditions. It is reported that tensile elongation increases two-fold at elevated temperature, without excessive grain growth. With the right selection of processing conditions, the formability of the plate, expressed as cup height deformed in a cupping test, can be enhanced—as much as 62% compared with room temperature when the processing takes place at 150 °C. The improvement in ductility was attributed to a reduced apparent activation volume due to grain refinement, which translated into improved strain rate sensitivity.

4

Microstructure and Hardness of Cold Forged 42CrMo4 Steel Hollow Component with the Outer Flange

Szala Mirosław, Winiarski Grzegorz, Bulzak Tomasz, Wójcik Łukasz

Advances in Science and Technology. Research Journal

|

2022

|

Vol. 16, no 4

201--210

EN

For decades, steel has been a crucial structural material. Mainly low-alloy steel grade ISO 42CrMo4 is utilized for manufacturing forgings. This paper investigates the microstructure and hardness development of the 42CrMo4 steel hollow component with an outer flange. The component has been formed via cold forging in combination with extrusion and upsetting technologies. Prior to forming, the workpiece was annealed to obtain hardness at the level of 181±9 HV0.3. The FEM analysis reveals the areas that undergo higher stress and strain. The flow lines macrostructure and microstructure of hollow parts were investigated using light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with EDS. Vickers hardness allows identifying the work hardening of the crucial element areas. The microstructure consists of ferrite matrix and semi-globular carbides. Laboratory studies confirm appropriate flow lines arrangement, which corresponds well to those shown by FEM computer simulations. The highest hardness at the level of 293±7 HV0.3 was identified in the flange area, where the material shows a higher distribution of effective strain revealed by FEM. Cold metal forming results in work-hardening of the steel. The work hardening ranges up to 1.62 of the initial 42CrMo4 steel hardness. The metal forming process did not affect the microstructural uniformity of the flanged hollow part. The final outer flange component presents high quality and is free from plastic deformation nonuniformities.

5

Inter-relationship between microstructure evolution and mechanical properties in inertia friction welded 8630 low-alloy steel

Banerjee Amborish, Ntovas Michail, Da Silva Laurie, Rahimi Salaheddin, Wynne Bradley

Archives of Civil and Mechanical Engineering

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2021

|

Vol. 21, no. 4

244--262

EN

The evolution of microstructure and mechanical properties in AISI 8630 low-alloy steel subjected to inertia friction welding (IFW) have been investigated. The effects of three critical process parameters, viz. rotational speed, friction and forge forces, during welding of tubular specimens were explored. The mechanical properties of these weld joints, including tensile and Charpy V-notch impact were studied for determining the optimum welding parameters. The weld joints exhibited higher yield strength, lower hardening capacity and ultimate tensile strength compared to base metal (BM). The maximum strength and ductility combination was achieved for the welds produced under a nominal weld speed of ~ 2900–3100 rpm, the highest friction force of ~ 680–720 kN, and the lowest axial forging load of ~ 560–600 kN. The measured hardness distribution depicted higher values for the weld zone (WZ) compared to the thermo-mechanically affected zone (TMAZ), heat-affected zone (HAZ) and BM, irrespective of the applied welding parameters. The substantial increase in the hardness of the WZ is due to the formation of microstructures that were dominated by martensite. The observed microstructural features, i.e. the fractions of martensite, bainite and ferrite, show that the temperature in the WZ and TMAZ was above Ac3, whereas that of the HAZ was below Ac1 during the IFW. The fracture surface of the tensile and impact-tested specimens exhibited the presence of dimples nucleating from the voids, thus indicating a ductile failure. EBSD maps of the WZ revealed the formation of subgrains inside the prior austenite grains, indicating the occurrence of continuous dynamic recrystallisation during the weld. Analysis of crystallographic texture indicated that the austenite microstructure (i.e. FCC) in both the WZ and TMAZ undergoes simple shear deformation during IFW.

6

Studies on influence of torch orientation on microstructure, mechanical properties and formability of AA5052 CMT welded blanks

Girinath B., Siva Shanmugam N., Sathiyanarayanan C.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

197--218

EN

Generally, in gas metal arc welding (GMAW) high heat input causes drastic changes in the microstructures of weldment (fusion zone and heat affected zone), which in turns affects the performance of the welded blanks during forming operation. The present study focuses on the parametric effects such as welding current, welding speed and torch orientation concerning welding direction on mechanical properties, microstructural characterization and formability of AA5052 Cold metal transfer (CMT) welded blanks (WB’s). Based on the macrostructure images obtained from various trials (trial 19, 20 and 21, which is corresponding to Drag angle of 10°, 90° or Zero angle and Push angle of 10°, respectively) three were selected for further studies. The macrograph, microstructural evaluation, mechanical behavior and forming limit curve (FLC) of the WB’s are examined for the selected parameters and for base metal (BM). The formability of the BM and WB’s are investigated by obtaining FLC using Nakajima test. Of the three different torch orientation concerning welding direction, the WB made with 10° push angle yields the superior mechanical properties such as high tensile strength, increase in hardness and more bending strength than the remaining torch orientations. In addition, total elongation and formability are of concern; drag angle of 10° yields the better result, compared to the other torch orientations.

7

Evaluation of Material Data to the Numerical Strain‑Life Analysis of the Compressor Blade Subjected to Resonance Vibrations

Bednarz Arkadiusz

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 1

184--190

EN

This paper presents the impact of selecting the fatigue material model on the numerically determined fatigue life of a compressor blade. In the work, the first stage compressor blade of the PZL‑10W turbine engine was used. The research object contained a geometric notch with a known location and shape. In numerical studies, 8 fatigue estimation methods were used in the ε ‑N analysis (based on the Manson‑Coffin‑Basquin model). At the same time, three methods for estimating material constants associated with the cyclic hardening were employed. On the basis of the selected models, 24 sets of fatigue parameters were obtained, which were used in numerical studies. The numerical tests were carried out under resonant conditions with amplitudes of 1.5 and 1.8 mm. The numerical tests were confirmed by the experimental fatigue tests. As a result of the above‑mentioned tests, the impact of selecting the material fatigue model and hardening model on the obtained results was determined and they were referred to the initiation of the crack with the length a = 0.2 mm (achieved during experimental studies). The obtained results will constitute the basis for further fatigue tests.

8

Insights into factors of damage of surface rolling of railway wheels during operation

Aaskerov Hangardas, Vakulenko Igor, Grischenko Nikolaji

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2019

|

z. 105

27--33

EN

The systematization results of microstructure studies of carbon steel has made it possible to explain the mechanism of formation of certain damages to the rolling surface of railway wheels during operation. The evaluation ability of metal to strain hardening was used to explain the nature of the influence compactly located non-deformable dispersed particles on the strength properties steel during cold plastic deformation. In the process of the interaction of a railway wheel with a rail, successively occurring heterogeneities in the distribution of the plastic flow metal are one of the main reasons for the formation of defects on the rolling surface of the wheel.

9

Umocnienie odkształceniowe kompozytów z stopu aluminium 6061+SiC

Zasadziński Łukasz, Zaborowski Krzysztof, Zasadziński Józef

Rudy i Metale Nieżelazne Recykling

|

2019

|

R. 64, nr 8

3--7

PL

W pracy przedstawiono wyniki badań dotyczących własności mechanicznych kompozytów ze stopu 6061+SiC umacnianych odkształceniowo na drodze ściskania i walcowania na zimno w szerokim zakresie odkształceń, sięgających gniotów względnych rzędu 80%. Zaprezentowane dane w postaci krzywych umocnienia, a także zależności twardości kompozytu i mikrotwardości osnowy kompozytu od wielkości odkształcenia. Dane te mogą być pomocne do projektowania wyrobów w technologiach wykorzystujących kształtowanie plastyczne na zimno kompozytów metalowych celem osiągnięcia maksymalnie wysokich własności mechanicznych.

EN

In the work the results relating to testing of mechanical properties of composites from 6061+SiC aluminium alloy, strain hardened by compression and cold rolling in the wide range of strain reached as high as 80% of reduction are presented. Presented data in the form of the true stress vs strain, as well as hardness of composite vs strain relationships can be helpful in designing of products in technologies using cold plastic forming of metallic composites with the aim of obtaining high mechanical properties.

10

Schematy technologiczne wytwarzania wyrobów z kompozytów metalowych umacnianych odkształceniowo

Zasadziński Łukasz

Rudy i Metale Nieżelazne Recykling

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2019

|

R. 64, nr 7

11--17

PL

W artykule zaprezentowano uproszczone wybrane schematy technologiczne wytwarzania podstawowych wyrobów takich jak blachy, taśmy, folie, pręty, druty, rury, kształtowniki, wytłoczki z kompozytów metalowych podatnych do umocnienia odkształceniowego. Zaproponowane schematy technologiczne uwzględniają niezbędne etapy potrzebne do wytworzenia danego wyrobu oraz specyfikę właściwości kompozytów metalowych, w tym kompozytów umacnianych twardymi cząstkami, które mogą być dodatkowo umacniane odkształceniowo w ramach kształtowania plastycznego na zimno.

EN

In the work the selected and simplified technological schedules for producing basic products, such as sheets, tapes, foils, bars, wires, tubes, profiles and drawpieces form metallic composites susceptible to strain hardening are presented. Proposed technological schedules ++necessary stages needed to produce a given product and specifics of properties of metallic composites which can be additionally strain hardened in the cold forming processes.

11

On the development and studies of nano- and micro-fiber hybridized strain hardened cementitious composite

Sindu B. S., Sasmal Saptarshi

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

348--359

EN

In this study, strain hardened cementitious composite is developed by systematically incorporating fibers of two different length scales, viz., PVA fibers (micro-fibers) and CNTs (nano-fibers) to improve the load transfer and crack formation mechanism at their corresponding scales. At first, the influence of individual fibers on the tension associated (axial tension-, fracture- and flexure-) properties is investigated. Then, the composite is developed using hybrid fibers with appropriate dosage to cater the desired performance. The tensile strength, stiffness, strain carrying capacity and fracture energy of the developed composite is found to be improved by almost 2 times, 3 times, 220 times and 130 times respectively to that of the original cement composite. The outstanding performance of the developed composite is resulted from the effective crack bridging and preferred load transfer in micro-scale due to incorporation of (a meagre amount of) hetero fibers of distinctly different length scales. In order to investigate the fracture and crack propagation phenomenon of the developed cementitious composite, Digital Image Correlation (DIC) technique is also employed. The findings of this study will lead towards development of multi-performance cementitious composite (MPCC) by tailoring the material to attain the desired level of strength, stiffness and ductility.

12

Ocena zmian topografii powierzchni blach poddanych odkształceniu plastycznemu

Trzepieciński T., Bąk Ł., Nowotyńska I., Bosiakov S.

Przegląd Mechaniczny

|

2018

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nr 3

32--36

PL

Umocnienie odkształceniowe materiału blach poddawanych wytłaczaniu decyduje o charakterze zjawisk tribologicznych w strefie kontaktu oraz determinuje konstytuowanie się topografii powierzchni blach, w szczególności wykazujących anizotropię właściwości mechanicznych. Materiałem badawczym były blachy stalowe walcowane na zimno, gatunku DC04, przeznaczone do obróbki plastycznej na zimno. Wpływ odkształcenia blachy na wielkość rzeczywistej powierzchni kontaktu powierzchni blach z narzędziem w procesie wytłaczania badano za pomocą wciskania wgłębnika z płaską powierzchnią roboczą. Po przekroczeniu pewnej wartości nacisku, zależnej od stopnia odkształcenia blachy, obserwowano brak wpływu wartości nacisku na zmianę pola powierzchni nośnej wierzchołków nierówności. Określono również, że wartość podstawowych parametrów chropowatości powierzchni zmienia się nieproporcjonalnie w stosunku do nacisku wgłębnika.

EN

The strain hardening of the sheet material subjected to deep drawing determines the nature of tribological phenomena in the contact area and determines the formation of the topography of the sheet surface exhibiting anisotropy of mechanical properties. The investigations were carried out on cold-rolled deep-drawing quality steel sheets DC04 destined for cold sheet metal forming. The influence of the sheet deformation on the true area of the contact of the sheet surfaces with the tool in the deep drawing process was examined by pressing the flat indenter into the sheet surface. After exceeding a certain pressure value depending on the degree of sheet deformation, no clear effect of the pressure value on the change of the bearing area ratio was observed. It was also determined that the value of the basic parameters of the surface roughness varied disproportionately with the pressure of the indenter.

13

Temperaturowe aspekty odkształcenia plastycznego stali austenitycznej wysokomanganowej przeznaczonej do produkcji drutu

Kozłowska A., Grajcar A., Adamiec A.

Hutnik, Wiadomości Hutnicze

|

2017

|

Vol. 84, nr 1

30--33

PL

W pracy zbadano możliwości zastosowania stali austenitycznej wysokomanganowej jako nowoczesnego materiału do produkcji drutów stalowych o wysokim potencjale odkształcenia plastycznego na zimno. Odkształcenie plastyczne symulowano w jednoosiowej próbie rozciągania w zakresie temperatury od 20°C do 200°C. Przeanalizowano rodzaj dominującego mechanizmu umocnienia (efekt TRIP lub/i efekt TWIP) w zależności od temperatury odkształcenia. Rozwój mikrostruktury monitorowano w przerywanych próbach rozciągania do odkształcenia wynoszącego 5%, 10%, 20% oraz do zerwania.

EN

In this study, the possibilities of the application of high-Mn austenitic steel as a material for the production of steel wires with high potential of cold plastic deformation were examined. The plastic deformation was simulated in a uniaxial tensile test in a temperature range of 20°C to 200°C. The dominant effect of strengthening mechanism of the steel (TRIP or/ and TWIP effect) depending on the temperature of plastic deformation was determined. Development of the microstructure was monitored in interrupted tensile tests to deformation of 5%, 10%, 20% and up to rupture.

14

A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part I: The hardening law

Petryk H., Stupkiewicz S.

Archives of Mechanics

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2016

|

Vol. 68, nr 6

459--485

EN

A simple gradient-enhancement of the classical continuum theory of plasticity of single crystals deformed by multislip is proposed for incorporating size effects in a manner consistent with phenomenological laws established in materials science. Despite considerable efforts in developing gradient theories, there is no consensus regarding the minimal set of physically based assumptions needed to capture the slip-gradient effects in metal single crystals and to provide a benchmark for more refined approaches. In order to make a step towards such a reference model, the concept of the tensorial density of geometrically necessary dislocations generated by slip-rate gradients is combined with a generalized form of the classical Taylor formula for the flow stress. In the governing equations in the rate form, the derived internal length scale is expressed through the current flow stress and standard parameters so that no further assumption is needed to define a characteristic length. It is shown that this internal length scale is directly related to the mean free path of dislocations and possesses physical interpretation which is frequently missing in other gradient-plasticity models.

15

Numeryczna symulacja testu zderzeniowego z uwzględnieniem umocnienia odkształceniowego w procesie wytwarzania energochłonnego elementu samochodu

Ambroziński M., Polak S., Gronostajski Z., Kuziak R., Chorzępa W., Pietrzyk M.

Mechanik

|

2015

|

R. 88, nr 2

92--97

PL

Przedmiotem artykułu jest ocena możliwości numerycznej symulacji zachowania się elementów nadwozia samochodu w czasie kolizji. Opisano problematykę związaną z wytwarzaniem elementów pochłaniających energię oraz doborem materiału na te elementy. Do analizy wybrano stal z mikrododatkami, stal dwufazową i stal z efektem umocnienia (TRIP). Przeprowadzono symulacje wytwarzania oraz eksploatacji, tj. test zderzeniowy (crash test), elementu karoserii samochodowej wykonanego z tych stali. W teście zderzeniowym przyjęto dwa modele materiału. W pierwszym pominięto odkształcenia materiału podczas wytwarzania elementu, natomiast w drugim uwzględniono lokalną niejednorodność odkształceń powstałych w trakcie tłoczenia. Wyniki obliczeń porównano z fizycznymi symulacjami testu zderzeniowego. Wykazano, że drugie podejście daje znacznie lepsze oszacowanie właściwości produktu dla stali z mikrododatkami i stali dwufazowej. Takiej poprawy dokładności nie uzyskano dla stali z efektem TRIP.

EN

Paper deals with an evaluation of possibilities of numerical simulations of car body parts during collision. Problem of manufacturing of the crash box and selection of materials for this part was described. Microalloyed steel, Dual Phase (DP) steel and TRIP (Transformation Induced Plasticity) steel were selected for the analysis. Numerical simulations of manufacturing of crash box and crash tests were performed for element made of the three selected steels. Two variants of material model were used in the simulations of the crash test. In the first variant earlier deformation of the material during manufacturing was neglected. In the second variant strains calculated in simulations of the stamping process were transferred to the crash box. Results of calculations were compared with physical simulations of the crash test. It was shown that the second variant gives improvement of the results for microalloyed and DP steels. This improvement was not observed for the TRIP steel.

16

Impact of rotary swaging and age hardening on mechanical properties of EN AW 2024

Kövér M., Sláma P., Palán J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

|

Vol. 72, nr 2

61--66

EN

Purpose: Invention of severe plastic deformation methods led to increased interest in ultra-fine grained materials. The hardenable aluminium alloys were extensively studied in the last decade. It was revealed that combination of severe plastic deformation and age hardening can significantly improve the material properties of these alloys. In this article we performed such progressive thermo-mechanical treatment and following mechanical testing and metallographic analysis. The aim was to evaluate the influence of this treatment on mechanical properties, mostly the effect of various age hardening temperatures and time. Aluminium alloy EN AW 2024 was chosen for the experimental procedures. Impact of processing parameters on mechanical properties was determined by tensile testing. Metallographic analysis was used for evaluation of the straining influence on grain morphology. In the conclusion we denoted significant strain hardening effect, present shear bands and change in aging kinetics. Design/methodology/approach: The experimental material was processed by progressive thermo-mechanical treatment. The evaluation was performed by simple tensile testing and light microscopy. The first conclusions were derived from determined mechanical properties and based on similarities in available publications with related topic. Findings: The research results roughly confirm the recovery-precipitation complementary effect, observed in other hardenable aluminium alloys or the same hardenable alloy deformed by other SPD technique. The impact of both parts of processing – deformation and age hardening on mechanical properties was evaluated. Research limitations/implications: Future detailed investigation of secondary phase particles and dislocation-precipitate interaction should be performed. This investigation was not performed as it requires transmission electron microscopy. Originality/value: The paper contains first impression on promising SPD technique. As the technique appeared only recently, very few articles were published, considering few light alloys. The paper can help to set parameters for other researchers in this field and promote commercialization of this progressive thermo-mechanical processing

17

Behaviour of ductile low porous materials with strain hardening in Taylor experiment

Włodarczyk E., Sarzyński M.

Biuletyn Wojskowej Akademii Technicznej

|

2015

|

Vol. 64, nr 2

69-101

EN

The paper deals with an analytical solution of a one-dimensional boundary value problem, describing behaviour of a ductile porous cylindrical rod, both during and after Taylor direct impact experiment (Taylor DIE). The solution provides a simple theoretical basis for dynamical investigations of ductile porous material. The solution was based on a plastic-rigid rate-independent material with strain hardening. For ductile low porous materials with strain hardening, all parameters are presented by means of the closed analytical formulae. The paper presents also a new experimental method of determining distributions of density and longitudinal engineering compressive strain (LECS) in a porous ductile rod, plastically deformed by Taylor DIE.

PL

W pracy zawarto analityczne rozwiązanie jednowymiarowego modelu opisującego zachowanie plastycznego, porowatego pręta w trakcie i po zakończeniu uderzeniowego testu Taylora (Taylor DIE). Rozwiązanie bazuje na sztywno-plastycznym modelu materiału ze wzmocnieniem odkształceniowym (nie uwzględnia szybkości odkształcenia) i stanowi teoretyczną podstawę do badań właściwości dynamicznych plastycznych materiałów porowatych. Rozwiązanie ma postać zamkniętych równań analitycznych. W pracy przedstawiono również nową eksperymentalną metodę określania rozkładu gęstości oraz jednoosiowego odkształcenia nominalnego porowatych próbek odkształconych uderzeniowym testem Taylora.

18

Odkształcalność graniczna blachy ze stopu żarowytrzymałego AMS 5599

Frącz W., Stachowicz F., Trzepieciński T., Pieja T.

Hutnik, Wiadomości Hutnicze

|

2014

|

Vol. 81, nr 7

442--445

PL

Przy ocenie odkształcalności blach najczęściej korzysta się z wyznaczania wartości wykładnika krzywej umocnienia odkształceniowego oraz współczynnika anizotropii właściwości plastycznych. Badania eksperymentalne blach z różnych materiałów wykazały zasadnicze różnice ich odkształcalności, określane jako „typu mosiądz” oraz „typu stal”, przejawiające się brakiem lub wyraźną zależnością poziomu odkształceń granicznych od stanu odkształcenia. W pracy zawarte są wyniki badania właściwości mechanicznych w próbie jednoosiowego rozciągania oraz krzywych odkształcalności granicznej (KOG) w teście wg Marciniaka z płaskim stemplem, dla blachy ze stopu AMS 5599. Przeprowadzono obliczenia przebiegu krzywej odkształcalności granicznej przy pomocy różnych metod − wyniki obliczeń porównano z wynikami eksperymentu.

EN

The formability of sheet metal has frequently been expressed by the value of strain hardening exponent and plastic anisotropy ratio. However experimental studies of formability of various materials have revealed basic differences in behaviour, such as the “brass-type” and the “steel-type”, exhibiting respectively, zero and positive dependence of forming limit on the strain ratio. In this study mechanical properties and the Forming Limit Diagram of the AMS 5599 sheet metal was determined using uniaxial tensile test and Mar ciniak’s flat bottomed punch test respectively. Different methods were used for the FLD calculation − results of these calculations were compared with experi mental results.

19

The Effect of Heat Treatment on the Properties of Zirconium - Carbon Steel Bimetal Produced By Explosion Welding

Prażmowski M., Paul H., Żok F.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 3

1143--1149

EN

This paper assesses the effect of various values of detonation velocity on the quality of the bond zone, and thus the properties of bimetal zirconium (Zr 700) - steel (P355NL). The research was carried out for as-bonded welds, i.e. immediately following explosion welding. The results of shearing, peeling and tensile tests as well as macro-scale structural analyses were presented. In order to determine the changes in the value of strain hardening, the microhardness measurements across the interface were carried out. Based on the performed analyses it can be claimed that, depending on the applied technological settings of welding, most cases displayed wavy bond with highly diversified parameters of the wave. The changes observed with the detonation velocity are non-monotonic. High detonation velocities favored the formation of waves with large height and length and strongly affect the increase of the volume of brittle melted zones. Increased volume of the melted regions results in strong decrease of strength properties of the clad. The analysis of strength test results allows claiming that a small volume of melted regions in the bond considerably improves the strength of the bond. As a result of explosion welding, strain hardening of the joined materials occurs near the interface. In the case of clad fabricated using high technological parameters the increase of strengthening and the depth of its influence in the interface area is observed.

PL

W pracy poddano ocenie wpływ zróżnicowanych wartości prędkości detonacji na jakość strefy połączenia, a tym samym własności bimetalu w układzie cyrkon (Zr 700) – stal (P355NL). Badania prowadzono dla złączy w stanie wyjściowym, tj. bezpośrednio po zgrzewaniu wybuchowym. Przedstawiono wyniki badań mechanicznych (próba ścinania, zginania bocznego, odrywania oraz rozciągania) oraz strukturalnych w skali makro. Obserwacje strukturalne w pobliżu strefy połączenia umożliwiły określenie charakterystyki granicy połączenia. W celu określenia zmian w wielkości umocnienia wykonano pomiary mikrotwardości w obszarze złącza, jak i warstwy nakładanej oraz podstawowej. W zależności od zastosowanych parametrów technologicznych procesu spajania uzyskano połączenie faliste o silnie zróżnicowanych parametrach fali. Zmiany obserwowane wraz ze wzrostem prędkości detonacji są niemonotoniczne. Duże prędkości detonacji sprzyjały tworzeniu się fali o dużej wysokości i długości oraz wyraźnemu wzrostowi udziału twardych i kruchych obszarów przetopień w strefie połączenia. Zwiększony udział obszarów przetopień powodował drastyczny spadek własności wytrzymałościowych platerów. Układy o optymalnej charakterystyce granicy połączenia oraz odpowiednio wysokich własnościach wytrzymałościowych otrzymano przy niskich wartościach prędkości detonacji. W wyniku procesu spajania następowało umocnienie obydwu łączonych materiałów w pobliżu granicy rozdziału.

20

FEM simulation of open die forging of a plate from material NIMONIC 80A in DEFORM 3D

Polakova I., Duchek M., Malecek L.

Archives of Materials Science and Engineering

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2014

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Vol. 66, nr 1

31--36

EN

Purpose: This article presents results of a three-dimensional FEM-simulation of open die forging of a plate from material NIMONIC 80A. The FEM-simulation was carried out in DEFORM 3D Multiple Operation. Design/methodology/approach: The open die forging simulation contains many sequence operations, each single stroke and displacement of dies had to be modelled. The FEM-simulation of the open die forging process was set in accordance with real process conditions. Findings: The main effect on the crack initiation was the decrease in temperature on a edge of the plate. The real forgings show transverse cracks on the surface which starts on edges of the plate during forging. A good agreement between the simulation and experiment results was observed. Research limitations/implications: The plastic behaviour of material NIMONIC 80A was defined by means of strain hardening data which was obtained on the basis of measured data from Rastegaev compression test. The desired final thickness of the plate was reached by two procedures to study the effect of an amount of a reduction. The first procedure comprised 8 reduction passes with three reheatings, and second procedure comprised 10 reduction passes with four reheatings. The data evaluation of crack initiation in the FEM-simulation was carried out by tensile tests on the specimens. Originality/value: This article describes the FEM-simulation of open die forging process that was set in accordance with real process conditions. The aim of this simulation was to analyze the effect of an amount of a reduction on crack initiationon a real plate and to suggest the optimization of the process.