Magnesium alloys have poor deformation properties at room temperature, and the application of an electric pulse current during deformation can improve the plastic-forming ability. In this study, the ...electric pulse rolling of AZ91D magnesium alloy specimens has been examined by changing the pulse output voltage. The results demonstrate that the best surface quality and lowest content (8.4 %) of the β-Mg17Al12 phase are achieved at an output voltage of 300 V. EBSD tests have revealed the lowest weave strength on {0002} and {100} at a pulse output voltage of 300 V, as well as the greatest enhancement of twinning. The maximum tensile strength was 165 MPa at an output voltage of 300 V, with a maximum elongation of 4.1 % at an output voltage of 200 V.
The combined effects of the reduction ratio and annealing conditions during cold rolling were investigated for the texture and anisotropy of an EN AW-8011A aluminium alloy. To characterize the ...microstructural and textural differences, a scanning electron microscope with electron back-scattered diffraction was used. To achieve low anisotropy, the three key factors of texture were exposed: a low fraction of deformed grains according to the average grain misorientation, a large amount of random texture components and the equivalent ratio between deformed and recrystallised texture components. The results of crystallographic texture analysis and anisotropy values revealed that the higher ratio of total cold deformation (cold rolling reduction) and the higher ratio of cold deformation after the intermediate annealing were more favourable for the final continuous annealing in terms of decreasing anisotropy. In contrast, the lower ratio of the cold deformation resulted in lower anisotropy when implementing batch annealing.
A new method for the composite rolling of 304/Q345R was explored in the present study. The composite interface of the composite plate was studied using a scanning electron microscope (SEM) and ...electron-backscatter diffraction (EBSD). The results showed that a composite interface was formed with corrugated connections, increasing the length of the composite interface. Furthermore, the elongation of the corrugated interface relative to the original wave interface and the original horizontal interface were 29.43 % and 59.12 %, respectively. The composite interface became a 3D ripple interface from the traditional 2D plane. In the EBSD analysis, the strain energy at the interface of the corrugated composite interface was large, especially in the composite interface of the wave-waist position, indicating that the position of the ripple interface had a large deformation degree. This deformation is beneficial to the interface oxide and broken hardened layer conducive to the interface of the complex.
Papers for the thermal transfer printing of UHF RFID antennas were prepared by coating and calendering. Real and imaginary components of the impedance of the UHF RFID antennas depended on their ...design, coating composition and conditions of paper calendering. Passive UHF RFID tags were constructed from antennas and chips whose real and imaginary components of impedance in the 860–960 MHz frequency band were at approximately the same level. The communication quality of passive UHF RFID tags was evaluated by measuring the reading range using the designed UHF RFID reading unit. The reading range of experimental UHF RFID tags with printed antennas on paper and commercial UHF RFID tags with chemically etched antennas on a PET film were identical in the 860 MHz frequency.
One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner ...thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (v). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min–1 went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.
Annealing of deformed martensite (high-temperature tempering) in St37 steel was studied. Different reductions in thickness were considered and compared with the behavior of as-quenched martensite ...during tempering. tempering of the asquenched martensite was accompanied by the formation of carbide particles, incomplete disappearance of the lath martensite morphology, and continuous decrease in hardness until reaching low values. However, during tempering of the cold rolled martensite, the precipitation of carbides in the lamellar structure, development of distinct equiaxed ultrafine grains through a continuous recrystallization mechanism, and a sudden hardness drop were characterized. The importance of cold rolling reduction and its amount were also discussed.
nema
Metalurški proizvodni procesi sastoje se od kontinuiranih, različitih tehnoloških procesa i sastoje se od toka materijala kao i opreme i strojeva. Specifičnosti metalurških proizvodnih preocesa su: ...dugački proizvodni procesi, velika inertnost procesa, struktura “stabala” u proizvodnom procesu (od korijena pa do lišća), visoka kapitalna ulaganja itd. Takva svojstva metalurških proizvodnih procesa rezultiraju nekim specifičnostima proizvodne logistike. Članak se bavi ovim specifičnostima i pojašnjava korištenje postojećih uvjeta u proizvodnom procesu kod kontinuiranog ljevanja čeličnih ploča, njihovo zagrijavanje u pećima na temperaturu valjanja i valjanje istih u čeličanama.
Prezentirana je analiza distribucije tolerancije kod valjanja cijevnog navoja s valjcima identičnog polumjera zaobljenja vrha navoja. Razrađeni su teorijski odnosi i metodologija za računanje ...promjera utiskivanja navoja s pretpostavljenom distribucijom tolerancije utiskivanja koje je mjereno pomoću istisnutog volumena materijala. Dani su ilustrirani primjeri razrađenih odnosa.
In the present work, texture evolution of AA7005 aluminum alloy during the accumulative roll bonding and conventionally rolled was investigated by X-ray diffraction. It was found that the dominant ...texture components of both samples were Brass, Copper, Rotated Cube and Goss components, but the ARB texture evolution was quicker and displayed complex features. When the number of ARB cycle increased, the intensity of texture components decreased at the second and third pass, then enhanced at the fourth pass, and finally decreased. During the ARB process there was a texture transition at the second and third pass from Brass and S to Rotated Cube components due to the shear texture which formed on the surface region and moved to the center during the next pass. The enhancement of texture intensity at the fourth pass might be attributed to the formation of nano shear bands. The texture intensity decreasing at final cycle was correlated to redundant shear strain and continuous recrystallization during the high ARB passes.
nema
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