Wyniki wyszukiwania - BazTech

1

Optimization of GTAW Process Parameters of Dissimilar Al-Mg Alloys for Enhanced Joint Strength - Taguchi Approach

Antony Prabu D., Jayakumar K.S., Madhavan Pillai Elangovan, Kumaresan G.

Archives of Metallurgy and Materials

|

2023

|

Vol. 68, iss. 2

599--606

EN

The Tungsten Inert Gas (TIG) welding processes one of the prevalent methods used for welding aluminum alloys. TIG welding is most commonly used due to its superiority in welding less dense materials. The most prevalent issues encountered with TIG welding aluminium alloys are porosity creation and cracking due to solidification, both of which result in lower mechanical properties. Because of the metal’s susceptibility to heat input, this occurs. The current work is the result of a desire to improve the mechanical properties of dissimilar aluminium metals: AA5052-H32 & AA5083-H111. The process parameters of TIG welding are optimized towards eliminating the previously discussed failure scenarios. Various optimization techniques exist towards obtaining optimizing processes such as Response Surface Methodology (RSM), Genetic Algorithm (GA), Artificial Neutral Network (ANN), Flower pollination algorithm, Taguchi method etc, The Taguchi method was chosen for the optimization of process parameters due to its inherent nature of solving problems of singular variance. The optimal parameters combination was determined i.e. welding current at 170 A, filler rod diameter 2.4 mm and Gas flow rate of 11 lpm. The optimized input parameter was used to TIG weld the confirmation specimen which are further investigated for mechanical and metallurgical characterizations. The parameters were optimized and the results indicate that the input current was found to be the most contributing towards improving mechanical properties over all the process parameters.

2

Feasibility study on contact heating warm forming of 7075-T6 aluminum alloy

Sun Lu, Zhang Zhiqiang, Song Zhenkun, Ren Mingwen, Jia Hongjie

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 3

art. no. e209, 2023

EN

7075 aluminum alloy is becoming an ideal material for the manufacture of vehicle body parts due to the demands for energy-saving and lighter vehicles. To solve the problem that the strength of 7075-T6 aluminum alloy decreases due to over-aging after warm forming, contact heating warm forming (CHWF) technology was proposed in this work. Contact heating is a fast and efficient heating method that can make the blank reach the target temperature in a very short time. In this work, the effect of contact heating on the mechanical properties and microstructures of 7075-T6 aluminum alloy after warm forming and paint-baking (PB) was studied. It only took about 11.5 s to heat the 2 mm 7075 aluminum alloy sheet to 200 ℃ by contact heating, and the strength and the hardness of the formed parts could reach 94% and 92.5% of T6 condition, respectively. In contrast, the heating furnace needed 690 s to heat the sheet to 200 °C, and the strength and the hardness of the formed parts were 87% and 85.4% of T6 condition, respectively. Due to the fast heating rate of contact heating (17.5 ℃/s), the atoms and vacancies in the matrix did not have time to undergo diffusion and aggregation, so that the precipitates could not coarsen obviously. As a result, most of the η' precipitates in the T6 condition were retained. However, long-term heating in the furnace led to the transformation of η' precipitates into coarse η phase and the loss of strength and hardness.

3

Static stability analysis of carbon nanotube reinforced polymeric composite doubly curved micro-shell panels

Huang Yong, Karami Behrouz, Shahsavari Davood, Tounsi Abdelouahed

Archives of Civil and Mechanical Engineering

|

2021

|

Vol. 21, no. 4

39--53

EN

The current work develops a size-dependent model to provide a comprehensive analysis of static stability in doubly curved micro-panels resting on an elastic foundation. The doubly curved panel is made of advanced composites which reinforced with carbon-based materials. A seven-unknown shear deformation theory in curvilinear coordinate is combined with a non-classical approach to obtain a suitable model to get an accurate result for mechanical performance of micro-size shells. To perform this aim, a virtual work of Hamilton statement is developed and then an analytical technique on the basis of double-Fourier series is implemented for the microshell with fully simply supported conditions in edges. Results show that, CNTs reinforced composite curved shells exhibit a hardening response under buckling. It is also showed that the greatest critical buckling load of the microshell is observed for the shell with spherical panel followed by elliptical, cylindrical, and hyperbolic panels, respectively. Moreover, change of CNTs weight fraction can significantly alter the static stability characteristics of CNTs reinforced composite curved size-dependent shells.

4

Modelling and Experimental Characterization of Processing Parameters in Vertical Twin Roll Casting of Aluminium Alloy A356

Dhindaw B., Singh S., Mandal A., Pandey A.

Archives of Foundry Engineering

|

2020

|

Vol. 20, iss. 4

121--132

EN

Production of near net shape thin strips using vertical twin roll casting method has been studied. In a typical VTRC process, the simultaneous action of solidification and rolling makes the process quite attractive as well as complicated. An industrially popular alloy A356 has been chosen for the VTRC processing. It is challenging to identify VTRC processing parameters for the alloy to produce thin strips because of its freezing range and complex composition. In the present work processing parameters of VTRC like roll speed, roll gap, melt superheat and the interface convective heat transfer coefficient have been investigated through modelling of the process. The mathematical model was developed which simultaneously solves the heat transfer, fluid flow and solidification, using commercial software COMSOL Multiphysics 5.4. VTRC sheets of alloy A356 were produced in an experimental set up and attempts were made to correlate the microstructures of VTRC A356 alloy to that predicted from the numerical studies to validate the model.

5

Study on modalities and microdefects of Al-Cu bimetallic tube by underwater explosive cladding

Yu Yong, Xu Peibao, Li Kai, Zhao Jun, Dai Yuntong, Ma Honghao, Yang Ming

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 4

1390--1398

EN

In this study, a screwed copper tube was cladded an aluminum tube by a new explosive cladding method. To study the modalities of the bonding interface, a light microscope was used to observe the bonding interface. To expose the weak position of the interface, a three-point bending test was conducted under extreme condition. Then the BSE (Backscattering Electron) images of the bent interfaces were obtained. Meanwhile, the EDS (Energy Disper-sive Spectrometry) analyses of the melted zone were performed. The results of the light microscopic observations show that there are four bonding modalities on the interface. They can be summarized to two bonding modalities: direct bonding and bonding with the melted zone. There are no macro cracks on the interface of the bent specimens, which represents a reliable joining generally. The elastic modulus of Al-Cu bimetallic tube along the axial direction is 85.2Gpa. The BSE images, the EDS analyses and the microhardness tests show the direct bonding with some characteristics of the micro wavy interface is a pretty nice bonding pattern. The melted zone composed of CuAl2 is a weak bonding pattern, which may affect the mechanical property of the joint.

6

Influence of electromagnetic riveting process on microstructures and mechanical properties of 2A10 and 6082 Al riveted structures

Dong Dongying, Sun Liqiang, Wang Qiong, Li Guangyao, Cui Junjia

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 4

1284--1294

EN

Electromagnetic riveting (EMR) technology had unique connection advantages compared to traditional riveting methods. The influence of EMR process on microstructures and mechani- cal properties for 2A10 and 6082 aluminum riveted structures was investigated by comparison with regular pressure riveting (RPR) process. The microstructures and mechanical properties of the two riveting processes were analyzed by optical microscopy and tensile testing machine, respectively. The micro-hardness and the interference amount were also investi- gated. The results showed that the main characteristic of the driven head was the shear zone. The grain deformation of the EMR in shear zone was more severe than that of the RPR. The width of the shear zone of the RPR was larger than that of the EMR. The trend of micro- hardness distribution was opposite along the direction of the shear zone. Meanwhile, the distribution of the interference amounts of EMR had a better uniformity. The failure mecha- nisms of shear tests of the EMR and RPR were same, but the pull-out tests were different. The dynamic loading had a great influence on the microstructures and mechanical properties of riveted structures, and the mechanical properties of EMR were significantly enhanced.

7

Passive methods of boiling heat transfer enhancement

Orman Ł. J., Radek N., Kapjor A., Karpisz D.

Technical Transactions

|

2018

|

Vol. 115, iss. 12

193--198

EN

The paper presents the issue of boiling heat transfer enhancement with the use of different passive techniques, namely the application of wire mesh coatings, capillary porous layers, pin – fins and laser treatment. Enhanced boiling heat transfer has been described as well as the research data of the authors that deals with microstructural coatings. The conducted experimental tests confirm the possibility of increasing heat fluxes transferred at the same superheat value due to the use of heat transfer enhancing techniques.

PL

W artykule przedstawiono zagadnienie intensyfikacji wymiany ciepła przy wrzeniu poprzez zastosowanie różnych pokryć tj. struktur siatkowych, kapilarno – porowatych, mikrożeber czy obróbki laserowej. Przybliżono zagadnienie intensyfikacji wymiany ciepła przy wrzeniu i opisano wyniki badań autorów, dotyczące intensyfikacji wrzenia na mikropowierzchniach strukturalnych. Przeprowadzone badania potwierdzają możliwości zwiększenia gęstości odbieranych strumieni ciepła przy tym samym przegrzaniu.

8

Investigation of Microstructures and Mechanical Properties of T92 Martensitic Steel/Super304 Austenitic Steel Weld Joints Made with Three Welding Consumables

Liang Z., Gui Y., Zhao Q.

Archives of Metallurgy and Materials

|

2018

|

Vol. 63, iss. 3

1249--1256

EN

The microstructures and mechanical properties of T92 martensitic steel/Super304 austenitic steel weld joints with three welding consumables were investigated. Three types of welding materials ERNiCr-3, ERNiCrCoMo-1and T-304H were utilized to obtain dissimilar welds by using gas tungsten arc weld (GTAW). The results show that heat affect zone (HAZ) of T92 steel consists of coarse-grained and fine-grained tempered martensites. The microstructures of joints produced from ERNiCrCoMo-1 consist of equiaxed dendrite and columnar dendrite grains, which are more complicated than that of ERNiCr-3. In the tensile tests, joints constructed from ERNiCrCoMo-1 and T-304H met the ASME standard. The highest fracture energy was observed in specimens with the welding material ERNiCrCoMo-1. Ni content in weld seam of ERNiCrCoMo-1 was highest, which was above 40%. In conclusion, the nickel alloy ERNiCrCoMo-1 was the most suitable welding material for joints produced from T92 martensitic steel/Super304 austenitic steel.

9

Analysis of the mechanical properties and of micrographs of refill friction stir spot welded 7075-T6 aluminium sheets

Kubit A., Kluz R., Trzepieciński T., Wydrzyński D., Bochnowski W.

Archives of Civil and Mechanical Engineering

|

2018

|

Vol. 18, no. 1

235--244

EN

The main aim of the investigations was to determine the significance of parameters of RFSSW for the strength parameters of the resulting joint. RFSSW joints were made in 0.8-mm-thick 7075-T6 aluminium alloy using different welding parameters (tool rotational speed v, tool plunge depth, and joining time). The load capacity of joints was determined by shear tests. The optimum welding parameters which assure the highest load capacity (4.09 kN) in the tensile/shear test are: tool rotational speed of 3000 rpm, tool plunge depth of 1.55 mm, and joining time of 1.25 s. In the conditions of the static tensile test under pure shear the highest joint capacity (6.48 kN) is found for the joint welded at a tool plunge depth of 1.7 mm. Depending on the tool plunge depth, three types of joint damage were observed during tensile/shear tests: plug type fracture, shear fracture, and plug-shearracture. Incomplete refill is the main weld defect observed which is located on the path along which the sleeve plunges into the sheet. It was also found that alclad between the upper and lower sheets worsens the joint quality between the stir zone and thermo-mechanically affected zone.

10

Study on Underwater Explosive Welding of Al-Steel Coaxial Pipes

Yu Y., Ma H., Zhao K., Shen Z., Cheng Y.

Central European Journal of Energetic Materials

|

2017

|

Vol. 14, no. 1

251--265

EN

In order to solve the aluminum surface ablation issue of Al-Steel bimetallic pipes manufactured by the explosive welding technique, a novel explosive welding system has been designed to weld Al-Steel coaxial pipes. The stand-off distance was chosen according to an empirical formula. A special Explosive Cord with an aluminum coating was used as the explosive. Four experiments were performed using Explosive Cords 1, 2, 3 and 4, respectively. In each experiment, three reliable PVDF (Polyvinylidene Fluoride) piezoelectric film sensors were used to sample the impact pressure between the parent pipe and the flyer pipe along the detonation direction. p-t Curves were obtained at different points on the bimetallic pipe manufactured by Explosive Cord 1. In order to observe the inner surface and to judge the bonding interface, specimens were cut along the axial direction. BSE (Backscattering Electron) images of the interfaces were obtained. According to these pictures from all of the specimens cut along the axial direction, the surface ablation phenomenon has disappeared. The bimetallic pipe manufactured by the new welding system using Explosive Cord 3 has an irregular wavy interface, between micro and small wavy interface, which is one of the best bonding forms.

11

Synthesis and characterization of amphiphilic chitosan derivatives as nano/microstructures

Goszczyńska A., Niemczyk A., Piegat A.

Engineering of Biomaterials

|

2016

|

Vol. 19, no. 138 spec. iss.

38

12

Efficient surfaces for boiling heat transfer enhancement

Radek N., Orman Ł. J., Kapjor A., Sladek A.

Czasopismo Techniczne. Mechanika

|

2016

|

Y. 113, iss. 4-M

3--8

EN

The paper discusses the use of efficient surfaces for heat transfer enhancement during a nucleate boiling heat transfer. Distilled water under ambient pressure was the working fluid in the presented experiment. The application of a brass mesh of 0.63 mm aperture and 0.20 mm wire diameter on the surface of a copper heater led to considerable improvement in the value of heat flux at low temperature differences of a few Kelvin, where the enhancement ratio exceeded 2. Such modified surfaces could be used in the design of more efficient heat exchangers e.g. in refrigeration systems.

PL

Artykuł dotyczy wykorzystania wydajnych powierzchni do intensyfikacji wrzenia. Czynnikiem roboczym w badaniach była woda destylowana. Zastosowanie siatki mosiężnej o prześwicie 0,63 mm i o grubości drutu 0,20 mm na powierzchni wymiennikowej skutkowało znacznym wzrostem gęstości strumienia ciepła w obszarze małych przegrzań, gdzie stopień intensyfikacji wymiany ciepła przekroczył 2. Takie modyfikowane powierzchnie mogą być wykorzystywane do projektowania bardziej wydajnych wymienników ciepła, np. w systemach chłodniczych.

13

Morphological diversity of microstructures occurring in selected recent bivalve shells and their ecological implications

Brom K. R., Szopa K.

Contemporary Trends in Geoscience

|

2016

|

Vol. 5, iss. 2

104--112

EN

Environmental adaptation of molluscs during evolution has led to form biomineral exoskeleton – shell. The main compound of their shells is calcium carbonate, which is represented by calcite and/or aragonite. The mineral part, together with the biopolymer matrix, forms many types of microstructures, which are differ in texture. Different types of internal shell microstructures are characteristic for some bivalve groups. Studied bivalve species (freshwater species – duck mussel (Anodonta anatina Linnaeus, 1758) and marine species – common cockle (Cerastoderma edule Linnaeus, 1758), lyrate Asiatic hard clam (Meretrix lyrata Sowerby II, 1851) and blue mussel (Mytilus edulis Linnaeus, 1758)) from different locations and environmental conditions, show that the internal shell microstructure with the shell morphology and thickness have critical impact to the ability to survive in changing environment and also to the probability of surviving predator attack. Moreover, more detailed studies on molluscan structures might be responsible for create mechanically resistant nanomaterials.

14

Synthesis and photocatalytic performance of spongy ZnO microstructures

Zou Y. L., Li Y., Wang Q., An D. M., Lian X. X., Lv T.

Materials Science Poland

|

2015

|

Vol. 33, No. 2

230--236

EN

Spongy ZnO microstructures were synthesized via a facile hydrothermal method using zinc nitrate hexahydrate and oxalic acid as raw materials. The as-obtained ZnO were characterized by powder X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and transmission electron spectroscopy (TEM), respectively. The BET surface area and average pore size of the samples were determined by nitrogen adsorption-desorption analysis. Effects of precursor and hydrothermal temperature on the morphology and photocatalytic activity of the products were investigated. SEM and TEM analysis indicated that the as-obtained spongy ZnO microstructures consisted of a large amount of ZnO particles with the average size of about 100 to 150 nm. The photocatalytic activities of the spongy ZnO microstructures were evaluated by photodegradation of methylene blue (MB) under UV light radiation. The results indicated that the ZnO synthesized at 150 °C for 10 h showed the highest photocatalytic activity and the degradation ratio of MB reached 99.5 % for 60 min of UV light irradiation with the light intensity of 10 mW cm-2.

15

Phase, microstructure and microwave dielectric properties of Mg0:95Ni0:05 Ti0:98Zr0:02O3 ceramics

Manan A., Khan D. N., Ullah A., Ahmad A. S.

Materials Science Poland

|

2015

|

Vol. 33, No. 1

95--99

EN

Mg0.95Ni0.05 Ti0.98Zr0.02O3 ceramics was prepared via conventional solid-state mixed-oxide route. The phase, microstructure and microwave dielectric properties of the sintered samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vector network analyzer. The microstructure comprised of circular and elongated plate-like grains. The semi quantitative analysis (EDS) of the circular and elongated grains revealed the existence of Mg0.95Ni0.05 T2O5 as a secondary phase along with the parent Mg0.95Ni0.05 Ti0.98Zr0.02O3r~17.1, Qufo~195855 ± 2550 GHz and tf ~ -46 ppm/K was achieved for the synthesized Mg0.95Ni0.05 Ti0.98Zr0.02O3 ceramics sintered at 1325 °C for 4 h.

16

Sedimentological interpretation and stratigraphical position of glacigenic deposits in the Napęków area (Holy Cross Mountains, Poland)

Ludwikowska-Kędzia M., Pawelec H., Adamiec G.

Geologos

|

2015

|

Vol. 21, No. 4

261--284

EN

The identification of depositional conditions and stratigraphical position of glacigenic deposits in the Napęków area is important for the genetic and stratigraphical interpretation of Quaternary deposits in the central part of the Holy Cross Mountains, as well as for a revision of the course and extent of Middle Polish (Saalian) glaciations. These deposits comprise a series of diamictons which occur between sandy-gravelly deposits. Based on results of macro- and microscopic sedimentological investigations, analysis of heavy mineral composition, roundness and frosting of quartz grains, as well as OSL dating, this complex must have formed during the Odranian Glaciation (Drenthe, Saalian, MIS 6). Sandy-gravelly deposits are of fluvioglacial and melt-out origin. Diamictons represent subglacial traction till. Their facies diversity is a result of variations in time and space, complex processes of deposition and deformation, responsible for their formation at the base of the active ice sheet. This glacigenic depositional complex was transformed by erosion-denudation and aeolian processes in a periglacial environment during the Vistulian (Weichselian, MIS 5d-2).

17

Studies of CdI2-Bi3 microstructures with optical methods, atomic force microscopy and positron annihilation spectroscopy

Karbovnyk I., Bolesta I., Rovetskii I, Velgosh S, Klym H.

Materials Science Poland

|

2014

|

Vol. 32, No. 3

391--395

EN

Results of the comprehensive morphological study of CdI2–BiI3 layered crystals are presented. Direct AFM observations of micro- and nanostructures formed in the volume of the crystals confirm the predictions made on the basis of positron annihilation spectroscopy studies. The model explaining the possible pores formation mechanism is proposed and validated by the results of luminescence measurements at 8 K.

18

Depositional environment of the glacigenic deposits from the Holy Cross Mountains (Poland) – interpretation based on macro- and microstructure analyses

Ludwikowska-Kędzia M., Pawelec H.

Geological Quarterly

|

2014

|

Vol. 58, No. 4

807–-826

EN

In this paper an attempt is made to identify the depositional environment of glacigenic deposits from the central part of the Holy Cross Mountains (Kielce-Łagów Valley). In this area, the primary glacial relief is very poorly visible, mainly due to its modification by subsequent denudation processes. The study is based on detailed sedimentological (macro- and microstructural) analysis of the deposits. The bottom part of the deposits consists of gravelly and sandy facies. They are overlain by diamicton facies, with a small proportion of sandy facies. Clayey/silty facies occur in minor quantities. The investigations indicate that these deposits represent an ice-marginal environment. Local stagnation of the ice sheet lobe was controlled by the geological structure of bedrock (karstified and faulted limestones) and the features of a fossil valley. The ice-marginal depositional environment is indicated by the predominance of sediment-gravity flow deposits, a low proportion of sorted deposits, as well as the interfingering/alternating of mass flow deposits and waterlain deposits. Deformation occurring in the deposits is of gravitational origin. They also show traces of periglacial processes. The deposits constituted an ice-marginal moraine (dry end moraine with limited topographic expression). Micromorphological analyses provided data for genetic identification of the deposits, and allowed the inference about rheology of deposition and deformation processes. However, in some cases, they did not allow unequivocal genetic classification of the deposits. The results of presented investigations confirm the opinion that detailed and complete explanation of deposit origin requires both micromorphological analyses and macroscopic field sedimentological and structural studies.

19

Kinetics of Grain Growth in 718 Ni-Base Superalloy

Huda Z., Zaharinie T., Metselaar H. S. C., Ibrahim S., Min Goh J.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 3

847--852

EN

The Haynes® 718 Ni-base superalloy has been investigated by use of modern material characterization, metallographic and heat treatment equipment. Grain growth annealing experiments at temperatures in the range of 1050 – 1200 oC (1323–1473K) for time durations in the range of 20 min-22h have been conducted. The kinetic equations and an Arrhenius-type equation have been applied to compute the grain-growth exponent n and the activation energy for grain growth, Qg, for the investigated alloy. The grain growth exponent, n, was computed to be in the range of 0.066-0.206; and the n values have been critically discussed in relation to the literature. The activation energy for grain growth, Qg, for the investigated alloy has been computed to be around 440 kJ/mol; and the Qg, data for the investigated alloy has been compared with other metals and alloys and ceramics; and critically analyzed in relation to our results.

PL

Nadstop na bazie niklu Haynes ® 718 badano przy użyciu nowoczesnych urządzeń do charakterystyki materiałów, metalografii i obróbki cieplnej. Przeprowadzono badania wzrostu ziarna podczas wyżarzania w zakresie temperatur 1050 - 1200 ° C (1323-1473K) w czasie trwania od 20 minut do 22 godzin. Równania kinetyczne i równanie typu Arrheniusa zostały zastosowane do obliczania wykładnika wzrostu ziarna n oraz energii aktywacji wzrostu ziarna, Qg, dla badanego stopu. Obliczona wartość wykładnika wzrostu ziarna, n, mieści się w zakresie od 0.066 do 0.206 i została krytycznie przedyskutowana w odniesieniu do literatury. Obliczona energia aktywacji wzrostu ziaren, Qg, wynosi dla badanego stopu na około 440 kJ / mol. Dane Qg dla badanego stopu porównywano z danymi dla innych metali, stopów i ceramiki oraz krytycznie analizowano w odniesieniu do naszych wyników.

20

Effect of solution treatment on microstructures and mechanical properties of 2099 Al–Li alloy

Lin Y., Zheng Z. Q., Li S. C.

Archives of Civil and Mechanical Engineering

|

2014

|

Vol. 14, no. 1

61--71

EN

The influence of the solution treatment on microstructures and mechanical properties of 2099 Al–Li alloy was investigated by means of optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile properties measurement. With increasing solution temperature, the quantity of primary particles in the alloy decreased, and the degree of recrystallization gradually increased, leading to softening of solution treated alloy. Dissolution of primary particles in the solution treatment process promoted δ′ and T1 phases to precipitate during sequent aging treatment resulting in increase of strength. The number of T1 phases increased to peak value when the alloy was solution treated at 540 °C because almost no further dissolution of Cu-containing particles occurred at higher temperature. However, exorbitant solution temperature caused the drastic increase in the size and quantity of recrystallized grains that softened the alloy. Thus, mechanical properties of aged alloy were determined by two mechanisms: precipitation strengthening and solution softening. Compared with solution temperature, solution time had less effect on microstructures and mechanical properties of alloy. The suitable solution treatment for 2099 Al–Li alloy was 540 °C for 1 h, treated by which the yield strength of the aged alloy was 604 MPa with the elongation of 7.9%.