Effect of friction stir back extrusion rotational speed on microstructure, mechanical properties, and corrosion behaviour of AZ91-Ca alloy

Mehdipour, Maryam; Aval, Hamed Jamshidi

doi:10.1016/j.jmrt.2023.06.189

Cited by 7 publications

(1 citation statement)

References 54 publications

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“…Given the importance of the degradation rate of Mg alloys, the present manuscript aims to evaluate the corrosion performance of HPDC AZ91 samples that were friction stir processed (FSPed) at high rotation rates. In the current literature overview [25][26][27][28][29], few studies are based on these aspects. Saikrishna et al [27] analysed the corrosion behaviour of FSPed AZ91 samples after annealing treatment at 340 • C and revealed an increment of the corrosion rate in a 0.9% NaCl solution.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed

Ghio,

Cerri

2023

Materials

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The AZ series of Mg alloys have become promising in several industrial fields thanks to its potential microstructure refinement and the β-Mg17Al12 eutectic that controls the mechanical behaviour. Simultaneously, the rapid degradation characterizing Mg alloys makes the investigation of their corrosion behaviour necessary. The present work considers high-pressure die cast (HPDC) AZ91 alloy to evaluate its corrosion behaviour in 1M NaCl solution and investigates how different friction stir process parameters can affect the corrosion responses. No studies analyse the effects induced by the friction stir processed zone, reached using high rotational speeds (>2000 rpm), on the unprocessed HPDC AZ91 alloy. In addition, the morphological analysis of the corroded surfaces having a friction stir processed zone, in which the grain refinement was not obtained, is not present in the literature yet. Microstructural features were investigated by optical microscope and X-ray diffraction analysis before and after the friction stir process. These were subsequently correlated to the corrosion responses after the immersion tests. The results show that HPDC samples with a very smooth surface have the best corrosion resistance with a corrosion rate lower than 3 mm/year, evaluated through the weight loss, compared to the rougher ones. Both the amount of β-Mg17Al12 eutectic and the wt.% Al in the α-Mg matrix, as well as the surface roughness, influence the corrosion behaviour of friction stir processed samples. The best corrosion resistance was obtained with an HPDC alloy processed at 2500 rpm and 50 mm/min.

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