Effect of Mg and Si on intermetallic formation and fracture behavior of pure aluminum-galvanized carbon-steel joints made by weld-brazing

Commercial pure aluminum and galvanized carbon steel were lap-welded using the weld-brazing (WB) technique. Three types of aluminum filler materials (4043, 4047, and 5356) were used for WB. The joint strength and intermetallic compounds at the interface of three series of samples were analyzed and compared. Depending on the Si content, a variety of ternary Al-Fe-Si intermetallic compounds (IMCs) such as Fe4(Al,Si)13, Fe2Al8Si(τ5) , and Fe2Al9Si2 (τ6) were formed at the interface. Mg element in 5356 filler material cannot contribute to the formation of Al-Fe intermetallic phases due to the positive mixing enthalpy of Mg-Fe. The presence of Mg enhances the hot cracking phenomenon near the Al-Fe intermetallic compound at the interface. Zn coating does not participate in intermetallic formation due to its evaporation during WB. It was concluded that the softening of the base metal in the heat-affected zone rather than the IMCs determines the joint efficiency.info:eu-repo/semantics/publishedVersio

Phenolic Compounds and Antioxidant Activity of Dried Peel of Iranian Pomegranate

Background: Literature review shows that there are not sufficient data about polyphenolic compounds of peel of Iranian pomegranate. So, this work was mainlyundertaken to determine phenolic compounds and antioxidant activity of dried peel of Iranian pomegranate. Methods: Pomegranate fruits were obtained from mature fruits grown in Saveh, Iran and the Pomegranate Peel (PP) were dried with three different methods. Powders of PP were extracted with four different solvents, using a soxhlet apparatus. The compounds of PP extracts were analyzed by High Performance Liquid Chromatography (HPLC). Then, yield percentage and Radical Scavenging Activity (RSA) were determined. Statistical analysis was performed using the SAS 9.1 software. Results: Different ranges of tannic acids, testosterone and α-estradiol, estriol, estrone, cyanidin 3-glucoside, cyanidin3,5-diglucoside, pelargonidin 3-glucoside, pelargonidin 3,5diglucoside, and delphinidin 3-glucoside were identified. Both the highest yield percentage (18.820±0.661) as well as the highest RSA percentage (63.862±0.376) were obtained from the ethanol showing significant (p0.05) relationship with yield of extraction and also antioxidant activity of the PP extracts. Conclusion: HPLC analysis identified some various phenolic compounds in Iranian PP extract showing considerable antioxidant activities. Although drying method showed no relation with yield of extraction and also antioxidant activity of the PP extracts, but type of solvent was effective on yield of extraction and type of extracted compounds of PP

A Parametric Study on the Effect of FSW Parameters and the Tool Geometry on the Tensile Strength of AA2024–AA7075 Joints: Microstructure and Fracture

Friction stir welding (FSW) is a process by which a joint can be made in a solid state. The complexity of the process due to metallurgical phenomena necessitates the use of models with the ability to accurately correlate the process parameters with the joint properties. In the present study, a multilayer perceptron (MLP) artificial neural network (ANN) was used to model and predict the ultimate tensile strength (UTS) of the joint between the AA2024 and AA7075 aluminum alloys. Three pin geometries, pyramidal, conical, and cylindrical, were used for welding. The rotation speed varied between 800 and 1200 rpm and the welding speed varied between 10 and 50 mm/min. The obtained ANN model was used in a simulated annealing algorithm (SA algorithm) to optimize the process to attain the maximum UTS. The SA algorithm yielded the cylindrical pin and rotational speed of 1110 rpm to achieve the maximum UTS (395 MPa), which agreed well with the experiment. Tensile testing and scanning electron microscopy (SEM) were used to assess the joint strength and the microstructure of the joints, respectively. Various defects were detected in the joints, such as a root kissing bond and unconsolidated banding structures, whose formations were dependent on the tool geometry and the rotation speed

A Parametric Study on the Effect of FSW Parameters and the Tool Geometry on the Tensile Strength of AA2024–AA7075 Joints: Microstructure and Fracture

Friction stir welding (FSW) is a process by which a joint can be made in a solid state. The complexity of the process due to metallurgical phenomena necessitates the use of models with the ability to accurately correlate the process parameters with the joint properties. In the present study, a multilayer perceptron (MLP) artificial neural network (ANN) was used to model and predict the ultimate tensile strength (UTS) of the joint between the AA2024 and AA7075 aluminum alloys. Three pin geometries, pyramidal, conical, and cylindrical, were used for welding. The rotation speed varied between 800 and 1200 rpm and the welding speed varied between 10 and 50 mm/min. The obtained ANN model was used in a simulated annealing algorithm (SA algorithm) to optimize the process to attain the maximum UTS. The SA algorithm yielded the cylindrical pin and rotational speed of 1110 rpm to achieve the maximum UTS (395 MPa), which agreed well with the experiment. Tensile testing and scanning electron microscopy (SEM) were used to assess the joint strength and the microstructure of the joints, respectively. Various defects were detected in the joints, such as a root kissing bond and unconsolidated banding structures, whose formations were dependent on the tool geometry and the rotation speed