scholarly journals Effect of the Shape of Rolling Passes and the Temperature on the Corrosion Protection of the Mg/Al Bimetallic Bars

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6926
Author(s):  
Sebastian Mróz ◽  
Karina Jagielska-Wiaderek ◽  
Piotr Szota ◽  
Andrzej Stefanik ◽  
Robert Kosturek ◽  
...  
Keyword(s):  
Explosive Welding ◽  
Experimental Tests ◽  
Rolling Process ◽  
Test Results ◽  
Aluminum Layer ◽  
The Core ◽  
Homogenous Distribution ◽  
Two Temperatures ◽  
Higher Temperature ◽  
Plating Layer

The paper presents the results of experimental tests of the rolling process of Mg/Al bimetallic bars in two systems of classic passes (horizontal oval-circle-horizontal oval-circle variant I) and modified (multi-radial horizontal oval-multi-radial vertical oval-multi-radial horizontal oval-circle-variant II). The feedstock in the form of round bimetallic bars with a diameter of 22 mm and 30% of the outer aluminum layer was made through explosive welding. The bimetallic bars consisted of an AZ31 magnesium core and a 1050A aluminum outer layer. Bars with a diameter of 17 mm were obtained as a result of rolling in four passes. The rolling process in the passes was conducted at two temperatures of 300 and 400 °C. Based on the analysis of the test results, it was found that the use of modified passes and a lower rolling temperature (300 °C) ensures a more homogenous distribution of the plating layer around the circumference of the core and results in an even grain decreasing, which improves the corrosion resistance of bimetallic bars compared to rolling bars in a classic system of passes and at a higher temperature (400 °C).

scholarly journals Microstructure and properties of 1050A/AZ31 bimetallic bars produced by explosive cladding and subsequent groove rolling process

2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Sebastian Mróz ◽  
Renata Mola ◽  
Piotr Szota ◽  
Andrzej Stefanik
Keyword(s):  
Intermetallic Layer ◽  
Experimental Tests ◽  
Rolling Process ◽  
Test Results ◽  
Shear Tests ◽  
Proper Selection ◽  
Bar Rolling ◽  
Explosive Cladding ◽  
Groove Rolling ◽  
Selection Of

Abstract Within the framework of this study, the 1050A/AZ31 round bimetal bars were produced by the explosive cladding method and subsequent groove rolling process. LM/SEM investigation shown that by proper selection of the explosive cladding parameters (mainly initial distance between 1050A tube and AZ31 core and detonation velocity) it is possible to produce 1050A/AZ31 feedstocks without a continuous layer of Mg–Al intermetallic phases on the interface between joined materials. The experimental tests of the groove rolling process of 1050A/AZ31 bars were supplemented with a theoretical analysis using FEM-based numerical modelling. Based on the test results obtained, it was found that the interface of the 1050A/AZ31 bar rolling at a temperature (300 °C) was characterized by the generation of a thin continuous intermetallic layer without cracks. Applying a higher rolling temperature of 400 °C, which is usually used in hot forming processes of Mg alloys, led to the production of a thicker intermetallic layer, which cracked during the rolling process as a result of deformation. Strength of the fabricated bimetal joints was high, they did not delaminate during shear tests.

scholarly journals Analysis of Al-Cu Bimetallic Bars Properties After Explosive Welding and Rolling in Modified Passes

2015 ◽  
Vol 60 (1) ◽  
pp. 427-432 ◽  
Author(s):  
S. Mróz ◽  
P. Szota ◽  
A. Stefanik ◽  
S. Wąsek ◽  
G. Stradomski
Keyword(s):  
Shear Strength ◽  
Uniform Distribution ◽  
Outer Layer ◽  
Explosive Welding ◽  
Experimental Tests ◽  
Rolling Process ◽  
High Quality ◽  
Cladding Layer ◽  
Welding Method

Abstract The paper presents the results of the experimental tests of Al-Cu bimetallic bars rolling process in multi-radial modified passes. The bimetallic bars consist of aluminium core, grade 1050A and copper outer layer, grade M1E. The stocks were round bars with diameter 22 mm with a copper layer share of 15 and 30%. As a result of rolling in four passes, bars of a diameter of about 16.0 mm were obtained. A bimetallic stock was manufactured using an explosive welding method. The use of the designed arrangement of multi-radial modified stretching passes resulted in obtaining Al-Cu bimetallic bars with the required lateral dimensions, an uniform distribution of the cladding layer over the bar perimeter and high quality of shear strength between individual layers.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

On axial compressive behavior of steel fiber reinforced concrete confined by FRP

2021 ◽  
pp. 136943322098165
Author(s):  
Hossein Saberi ◽  
Farzad Hatami ◽  
Alireza Rahai
Keyword(s):  
Reinforced Concrete ◽  
Experimental Test ◽  
Steel Fiber ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Frp Confinement

In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.

scholarly journals The Chosen Aspects of Skew Rolling of Hollow Stepped Shafts

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 764
Author(s):  
Jarosław Bartnicki ◽  
Yingxiang Xia ◽  
Xuedao Shu
Keyword(s):  
Cross Section ◽  
Rolling Mill ◽  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Numerical Control ◽  
Technological Parameters ◽  
Flow Mechanisms ◽  
The Individual ◽  
Skew Rolling

The paper presents chosen aspects of the skew rolling process of hollow stepped products with the use of a skew rolling mill designed and manufactured at the Lublin University of Technology. This machine is characterized by the numerical control of spacing between the working rolls and the sequence of the gripper axial movement, which allows for the individual programming of the obtained shapes of parts such as stepped axles and shafts. The length of these zones and the values of possibly realizable cross-section reduction and obtained outlines are the subject of this research paper. The chosen results regarding the influence of the technological parameters used on the course of the process are shown in the present study. Numerical modelling using the finite element method in Simufact Forming, as well as the results of experimental tests performed in a skew rolling mill, were applied in the conducted research. The work takes into account the influence of cross-section reduction of the hollow parts and the feed rate per rotation on the metal flow mechanisms in the skew rolling process. The presented results concern the obtained dimensional deviations and changes in the wall thickness determining the proper choice of technological parameters for hollow parts formed by the skew rolling method. Knowledge about the cause of the occurrence of these limitations is very important for the development of this technology and the choice of the process parameters.

scholarly journals Methodology for Selecting the Operating Conditions of a Vibration Generator Used in the Hot-Dip Galvanizing Process

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2042
Author(s):  
Wojciech Kacalak ◽  
Igor Maciejewski ◽  
Dariusz Lipiński ◽  
Błażej Bałasz
Keyword(s):  
Simulation Model ◽  
Asynchronous Motor ◽  
Experimental Tests ◽  
Suspension System ◽  
Operating Conditions ◽  
Test Results ◽  
Forced Simulation

A simulation model and the results of experimental tests of a vibration generator in applications for the hot-dip galvanizing process are presented. The parameters of the work of the asynchronous motor forcing the system vibrations were determined, as well as the degree of unbalance enabling the vibrations of galvanized elements weighing up to 500 kg to be forced. Simulation and experimental tests of the designed and then constructed vibration generator were carried out at different intensities of the unbalanced rotating mass of the motor. Based on the obtained test results, the generator operating conditions were determined at which the highest values of the amplitude of vibrations transmitted through the suspension system to the galvanized elements were obtained.

scholarly journals Experimental Tests for Measuring Individual Attentional Characteristics in Songbirds

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2233
Author(s):  
Loïc Pougnault ◽  
Hugo Cousillas ◽  
Christine Heyraud ◽  
Ludwig Huber ◽  
Martine Hausberger ◽  
...  
Keyword(s):  
Cognitive Processes ◽  
Comparative Research ◽  
Visual Stimuli ◽  
Experimental Tests ◽  
European Starling ◽  
Auditory Stimuli ◽  
The Core ◽  
Cognitive Studies ◽  
Individual Variations ◽  
Species Specific

Attention is defined as the ability to process selectively one aspect of the environment over others and is at the core of all cognitive processes such as learning, memorization, and categorization. Thus, evaluating and comparing attentional characteristics between individuals and according to situations is an important aspect of cognitive studies. Recent studies showed the interest of analyzing spontaneous attention in standardized situations, but data are still scarce, especially for songbirds. The present study adapted three tests of attention (towards visual non-social, visual social, and auditory stimuli) as tools for future comparative research in the European starling (Sturnus vulgaris), a species that is well known to present individual variations in social learning or engagement. Our results reveal that attentional characteristics (glances versus gazes) vary according to the stimulus broadcasted: more gazes towards unusual visual stimuli and species-specific auditory stimuli and more glances towards species-specific visual stimuli and hetero-specific auditory stimuli. This study revealing individual variations shows that these tests constitute a very useful and easy-to-use tool for evaluating spontaneous individual attentional characteristics and their modulation by a variety of factors. Our results also indicate that attentional skills are not a uniform concept and depend upon the modality and the stimulus type.

scholarly journals North Atlantic warming over six decades drives decreases in krill abundance with no associated range shift

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Martin Edwards ◽  
Pierre Hélaouët ◽  
Eric Goberville ◽  
Alistair Lindley ◽  
Geraint A. Tarling ◽  
...  
Keyword(s):  
North Atlantic ◽  
Range Shift ◽  
The Core ◽  
Krill Abundance ◽  
The North ◽  
Living Space ◽  
Warming Climate ◽  
Two Temperatures ◽  
The North Atlantic

AbstractIn the North Atlantic, euphausiids (krill) form a major link between primary production and predators including commercially exploited fish. This basin is warming very rapidly, with species expected to shift northwards following their thermal tolerances. Here we show, however, that there has been a 50% decline in surface krill abundance over the last 60 years that occurred in situ, with no associated range shift. While we relate these changes to the warming climate, our study is the first to document an in situ squeeze on living space within this system. The warmer isotherms are shifting measurably northwards but cooler isotherms have remained relatively static, stalled by the subpolar fronts in the NW Atlantic. Consequently the two temperatures defining the core of krill distribution (7–13 °C) were 8° of latitude apart 60 years ago but are presently only 4° apart. Over the 60 year period the core latitudinal distribution of euphausiids has remained relatively stable so a ‘habitat squeeze’, with loss of 4° of latitude in living space, could explain the decline in krill. This highlights that, as the temperature warms, not all species can track isotherms and shift northward at the same rate with both losers and winners emerging under the ‘Atlantification’ of the sub-Arctic.

scholarly journals The Effect of Process Parameters in Helical Rolling of Balls on the Quality of Products and the Forming Process

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2125 ◽  
Author(s):  
Janusz Tomczak ◽  
Zbigniew Pater ◽  
Tomasz Bulzak
Keyword(s):  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Helical Rolling ◽  
Forming Process ◽  
University Of Technology ◽  
Quality Of Products ◽  
Skew Rolling

This paper presents selected numerical and experimental results of a skew rolling process for producing balls using helical tools. The study investigates the effect of the billet’s initial temperature on the quality of produced balls and the rolling process itself. In addition, the effect of billet diameter on the quality of produced balls is investigated. Experimental tests were performed using a helical rolling mill available at the Lublin University of Technology. The experiments consisted of rolling 40 mm diameter balls with the use of two helical tools. To determine optimal rolling parameters ensuring the highest quality of produced balls, numerical modelling was performed using the finite element method in the Forge software. The numerical analysis involved the determination of metal flow kinematics, temperature and damage criterion distributions, as well as the measurement of variations in the force parameters. The results demonstrate that the highest quality balls are produced from billet preheated to approximately 1000 °C.

The Oxide Defect of C70250 Alloy

2014 ◽  
Vol 936 ◽  
pp. 1168-1172 ◽  
Author(s):  
Zhong Ping Chen ◽  
Chao Jian Xiang ◽  
Hua Qing Li
Keyword(s):  
High Temperature Oxidation ◽  
Rolling Process ◽  
Pilot Scale ◽  
Processing Temperature ◽  
Skin Defect ◽  
Test Results ◽  
Temperature Oxidation ◽  
Reducing Atmosphere ◽  
Hot Rolling Process ◽  
Oxide Skin

The oxide skin defect during hot rolling process for Cu-Ni-Si alloy strip was investigated. Oxide skin defects were analyzed by means of alloy elements detection and microstructures characterization. The characterization and test results showed that high temperature oxidation and silicon segregation are the main causes of the oxide skin defect. Pilot scale tests indicated that hot processing temperature for C70250 alloy should be lower than 950°C. Reducing atmosphere is recommended during the thermal treatment of Cu-Ni-Si alloys.

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