Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"AHMED M. EL-AZIZ"

Microstructure and corrosion behaviour of magnesium alloy AZ91: Infl uence of rare earths as alloying elements

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Magnesium alloys have low densities and potentially high strength/weight ratio, therefore have a great interest for application in automotive, aerospace and bioengineering. However, corrosion resistance is a factor limiting their more wide application. Addition of alloying elements like aluminum and zinc may improve the mechanical and the corrosion behaviour. The purpose of this paper is to study microstructure and corrosion behaviour of magnesium AZ91 and the infl uence of rare earth elements (mesh metal up to a certain weight) addition. The infl uence of the main constituent phases on the corrosion behaviour was studied by scanning electron microscopy and energy dispersive X-ray. α (Matrix) and β (grain boundary) phases as well as dendrite precipitate of rare earth elemen[...]

Mechanical and corrosion behaviour of hot stamped 22MnB5/Usibor 1500 steel alloy Yb:YAG continuous fi ber laser weldments


  The hot stamped 22MnB5/Usibor 1500 is one of the best steel alloys used today in the car manufacturing industry. Therefore, the welding and their effect on the properties of this alloy is the study concern for the application. The aim of this work is to investigate and compare between the metallurgical, mechanical, and corrosion behavior of butt welding of 22MnB5 without Al/ Si layer and with Al/Si layer (Usibor 1500) steels. The welding was carried out byYb:YAG continuous fi ber laser with material thickness 1.0 mm. The welding bead slightly increases with the increase of laser welding velocity. The heat affected zone (HAZ) width isinversely proportionate to the laser welding velocity. AlthoughUsibor 1500 steel undergoes a martensite structure, however its structure in the HAZ and fusion line is dependent on laser welding velocity. Higher ferrite content was observed in the HAZ with higher laser velocity. The hardness distribution was signifi cantly affected with the changes in the microstructure. Electrochemical corrosion testing was used to evaluate the corrosion behaviour of the welded workpieces. The welded material is more susceptible to pitting than the un-welded material. Higher corrosion resistance was obtained in case of coated than rather uncoated workpieces. Keywords: 22MnB5 steels, fi ber laser welding, hot stamping process, corrosion, mechanical Zachowanie mechaniczne i korozyjne tłoczonych na gorąco stopów stali 22MnB5/Usibor 1500 spawanych z użyciem laserów włókowych pracujących w reżimie pracy ciągłej Tłoczona na gorąco stal 22MnB5/Usibor 1500 jest jednym z najlepszych stopów stosowanych dziś w branży motoryzacyjnej. Spawanie tych stali oraz zrozumienie wpływu spawania na ich właściwości jest kluczowe. Celem pracy jest zbadanie i porównanie zachowania doczołowo spawanej stali 22MnB5 bez warstwy Al/Si i stali Usibor 1500 z warstwą Al/Si. Spawanie wykonano za pomocą lasera włóknowego Yb:YAG pracującego w reżimie pracy ciągłe[...]

Microstructure and corrosion behaviour of Al-Si alloy treated by high intensity ultrasonic vibrations

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The effect of ultrasonic liquid metal treatment on the microstructure and the corrosion behaviour of the A356 Al-Si alloy was studied. The microstructures of the Al-Si were observed by means of optical and scanning electron microscopes. The corrosion behaviour was studied electrochemically and by gravimetric method. The results showed that the microstructure was modifi ed from a coarse acicular plate-like form when no ultrasonic vibration was used, to a fi nely dispersed rosette-like form when ultrasonic treatment was employed. The ultrasonically treated samples showed higher resistance to pitting than the untreated sample. The soaking process negatively affected the pitting resistance. Keywords: Al-Si alloy, ultrasonic treatment, microstructure, corrosion Mikrostruktura i zachowanie korozyjne stopu Al-Si poddanego obróbce falami ultradźwiękowymi o dużym natężeniu Badano wpływ ultradźwiękowej obróbki ciekłego metalu na mikrostrukturę i zachowanie korozyjne stopu A356 Al-Si. Mikrostruktury Al-Si obserwowano przy użyciu mikroskopu optycznego i elektronowego mikroskopu skaningowego. Zachowanie korozyjne badano metodami elektrochemicznymi i metodą grawimetryczną. Wyniki badań wykazały, że po obróbce ultradźwiękowej, mikrostruktura uległa przekształceniu z płaskich i szorstkich igiełek do postaci drobno rozproszonej w kształcie rozety. Próbki po obróbce ultradźwiękami wykazywały większą odporność na korozję wżerową niż próbki bez obróbki , natomiast moczenie odporność tę pogorszyło. Słowa kluczowe: stop Al-Si, obróbka ultradźwiękowa, mikrostruktura, korozja 1. Introduction Aluminium alloys with silicon as a major alloying element constitute a class of materials that have wide-ranging applications in the automotive and aerospace industries [1]. Mechanical and corrosion properties of aluminium- silicon alloys can be signifi cantly improved by inducing structural modifi cation in the normally occurring eutectic. In general, the great[...]

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