Aluminium and aluminium alloys. Castings. Chemical composition and mechanical properties

1998 ◽  
2016 ◽  
Vol 61 (1) ◽  
pp. 353-360 ◽  
Author(s):  
B. Dybowski ◽  
J. Szymszal ◽  
Ł. Poloczek ◽  
A. Kiełbus

Due to low density and good mechanical properties, aluminium alloys are widely applied in transportation industry. Moreover, they are characterized by the specific physical properties, such as high electrical conductivity. This led to application of the hypoeutectic Al-Si-Mg alloys in the power generation industry. Proper selection of the alloys chemical composition is an important stage in achievement of the demanded properties. The following paper presents results of the research on the influence of alloys chemical composition on their properties. It has been revealed that Si and Ti addition decreases electrical conductivity of the Al-Si-Mg alloys, while Na addition increases it. The mechanical properties of the investigated alloys are decreased by both silicon and iron presence. Sodium addition increases ductility of the Al-Si-Mg alloys.


2019 ◽  
Vol 85 (12) ◽  
pp. 43-50
Author(s):  
D. A. Movenko ◽  
L. V. Morozova ◽  
S. V. Shurtakov

The results of studying operational destruction of a high-loaded cardan shaft of the propeller engine made of steel 38KhN3MFA are presented to elucidate the cause of damage and develop a set of recommendations and measures aimed at elimination of adverse factors. Methods of scanning electron and optical microscopy, as well as X-ray spectral microanalysis are used to determine the mechanical properties, chemical composition, microstructure, and fracture pattern of cardan shaft fragments. It is shown that the mechanical properties and chemical composition of the material correspond to the requirements of the regulatory documentation, defects of metallurgical origin both in the shaft metal and in the fractures are absent. The microstructure of the studied shaft fragments is tempered martensite. Fractographic analysis revealed that the destruction of cardan shaft occurred by a static mechanism. The fracture surface is coated with corrosion products. The revealed cracks developed by the mechanism of corrosion cracking due to violation of the protective coating on the shaft. The results of the study showed that the destruction of the cardan shaft of a propeller engine made of steel 38Kh3MFA occurred due to formation and development of spiral cracks by the mechanism of stress corrosion cracking under loads below the yield point of steel. The reason for «neck» formation upon destruction of the shaft fragment is attributed to the yield point of steel attained during operation. Regular preventive inspections are recommended to assess the safety of the protective coating on the shaft surface to exclude formation and development of corrosion cracks.


2020 ◽  
pp. 5-18
Author(s):  
D. V. Prosvirnin ◽  
◽  
M. S. Larionov ◽  
S. V. Pivovarchik ◽  
A. G. Kolmakov ◽  
...  

A review of the literature data on the structural features of TRIP / TWIP steels, their relationship with mechanical properties and the relationship of strength parameters under static and cyclic loading was carried out. It is shown that the level of mechanical properties of such steels is determined by the chemical composition and processing technology (thermal and thermomechanical processing, hot and cold pressure treatment), aimed at achieving a favorable phase composition. At the atomic level, the most important factor is stacking fault energy, the level of which will be decisive in the formation of austenite twins and / or the formation of strain martensite. By selecting the chemical composition, it is possible to set the stacking fault energy corresponding to the necessary mechanical characteristics. In the case of cyclic loads, an important role is played by the strain rate and the maximum load during testing. So at high loading rates and a load approaching the yield strength under tension, the intensity of the twinning processes and the formation of martensite increases. It is shown that one of the relevant ways to further increase of the structural and functional properties of TRIP and TWIP steels is the creation of composite materials on their basis. At present, surface modification and coating, especially by ion-vacuum methods, can be considered the most promising direction for the creation of such composites.


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