Corrosion Resistance of Friction Stir Processed AZ91D Magnesium Alloy under a Salt Fog Environment

2015 ◽  
Vol 787 ◽  
pp. 426-430 ◽  
Author(s):  
Jason Christopher Jolly ◽  
V. Karthik Srinivas ◽  
A.K. Lakshminarayanan

Magnesium alloys are widely used in applications where weight reduction is of primary importance. MgAZ91D is an Mg-Al-Zn alloy and its application in the automotive sector is limited by its poor corrosion resistance. Recent advances in solid state processing techniques have made it easier to modify the mechanical and corrosion characteristics of various alloys. Friction stir processing (FSP) is such a solid-state process for surface and sub-surface modification, which increases the microstructural densification, thereby producing fine and equiaxed grains. Through this work, an attempt was made to analyse the effect of friction stir processing on the corrosion resistance of the alloy in an enclosed salt spray chamber. Micro-analysis tools like FESEM and EDS are used to supplement our results. It is seen that, FSP significantly contributes to the increase in the corrosion resistance by homogenising the distribution of α and β phases and hence making the use of the alloy more practical in moisture rich environments.

2016 ◽  
Vol 861 ◽  
pp. 236-240 ◽  
Author(s):  
Zheng Lin Du ◽  
Ming Jen Tan ◽  
Jun Feng Guo ◽  
Jun Wei

Friction Stir Processing is a solid state process with the ability to modify microstructure and refine grain sizes of the material without melting and uniformly disperse reinforcement particles in the material matrix resulting in further improvements in the mechanical properties. In this study, it was used to disperse Al2O3 reinforcement particles of different sizes. Uniform dispersion of the reinforcements was achieved in the aluminium matrix with significant reduction in grain size were observed via SEM and EBSD. Improvement in Vicker’s micro hardness was observed after FSP.


2019 ◽  
Vol 8 (2) ◽  
pp. 1951-1956

Friction Stir Welding (FSW) is a vital solid-state process that can produce a joint with high quality and strength. The microstructure of the friction stir welded parts needs to be studied to use this method for multiple applications. FSW eliminates fusion fastening issues such as crack, porosity, and shrinking solidification. In the present work, AA6063 material was welded with prominent parameters, rotational speed, transverse speed, and axial load. The microstructure of distinct weld regions including the nugget area, heat affected zone, thermo-mechanically affected zone, and parent metal has been examined by optical microscopy. In this investigation the fine equiaxed grains were observed in the thermo-mechanically affected zone and nugget zone of various samples.


2015 ◽  
Vol 787 ◽  
pp. 421-425
Author(s):  
A. Vignesh ◽  
V.G. Vijay Prakaash ◽  
A.K. Lakshminarayanan

An attempt is made to modify the surface metallurgically and enhance the wear resistance of AISI 316LN austenitic stainless steel using friction stir processing. Friction stir welding tools made up of tungsten based alloy with pin and pinless configuration was used. Fine equiaxed grains were observed in the friction stir processed zone irrespective of tool configuration used. Dry sliding wear resistance was evaluated using pin-on-disc wear tester and it is found that, the friction stir processed zone showed superior wear resistance compared to the base metal. Microstructure, micro hardness, and worn surfaces were used to correlate the results obtained.


2019 ◽  
Vol 26 (06) ◽  
pp. 1850213 ◽  
Author(s):  
BEHZAD HASSANI ◽  
RUDOLF VALLANT ◽  
FATHALLAH KARIMZADEH ◽  
MOHAMMAD HOSSEIN ENAYATI ◽  
SOHEIL SABOONI ◽  
...  

The corrosion behavior of as-cast AZ91C magnesium alloy was studied by performing friction stir processing (FSP) and FSP followed by solution annealing and then aging. Phase analysis, microstructural characterization, potentiodynamic polarization test and immersion tests were carried out to relate the corrosion behavior to the samples microstructure. The microstructural observations revealed the breakage and dissolution of coarse dendritic microstructure as well as the coarse secondary [Formula: see text]-Mg[Formula: see text]Al[Formula: see text] phase which resulted in a homogenized and fine grained microstructure (15[Formula: see text][Formula: see text]m). T6 heat treatment resulted in an excessive growth and dispersion of the secondary phases in the microstructure of FSP zone. The potentiodynamic polarization and immersion tests proved a significant effect of both FSP and FSP followed by T6 on increasing the corrosion resistance of the cast AZ91C magnesium alloy. Improve in corrosion resistance after FSP was attributed to grain refinement and elimination of segregations and casting defects which makes more adhesive passive layer. Increase in volume fraction of precipitations after T6 heat treatment is determined to be the main factor which stabilizes the passive layer at different polarization values and is considered to be responsible for increasing the corrosion resistance.


2013 ◽  
Vol 747-748 ◽  
pp. 313-319 ◽  
Author(s):  
Fen Cheng Liu ◽  
Qiang Liu ◽  
Chun Ping Huang ◽  
Kun Yang ◽  
Cheng Gang Yang ◽  
...  

AZ80/Al composite plate was fabricated by means of friction stir processing (FSP) aimed at the improvement of corrosion resistance of magnesium alloy. The cross-section microstructure, surface morphology and corrosion resistance of the Al composite layer were investigated. The experiment results indicated that a dense composite Al layer with superfine and uniform grains was formed, and a few amount of intermetallic compounds existed in the area of Mg/Al interface. The bonding strength of AZ80 magnesium alloy substrate and 1060 pure Al layer was proved to be high which was resulted from the metallurgical bonding of FSP. Microhardness measurement showed the continuous changing of microhardness values from the outmost surface of composite Al layer to the magnesium alloy substrate. Results of electrochemical corrosion test of the composite plate in 5 wt.% NaCl solution showed the better protection effect of the composite Al layer on the magnesium alloy in a corrosion medium. Almost the same corrosion level on the whole corrosion surface was observed which indicated the highly uniform microstructure of the composite layer. It was also proved that the plain arches on the outmost surface of the composite Al layer had no influence on the corrosion resistance of composite Al layer.


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