Microhardness of eutectic Al-Si alloy after friction stir processing and annealing Article Swipe
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· 2022
· Open Access
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· DOI: https://doi.org/10.22226/2410-3535-2022-4-420-423
· OA: W4311397160
The plate of eutectic Al-Si alloy (AK12D) with a thickness of about 5 mm was subjected to friction stir processing (FSP). Samples for the study were cut perpendicular to the welding direction. Next, the samples were annealed for 1 h in the temperature range 150 – 500°C, quenched in water, and subjected to natural aging for 3 months. Thermal stability of the microstructure in various zones after FSP and subsequent annealing was studied by scanning electron microscopy. The volume fractions of dendrites and thickness of the eutectic interlayers were calculated depending on the annealing temperature. It was found that in none of the zones did annealing up to Т = 500°C lead to a noticeable change in the microstructure of the alloy. It has been established that the temperature dependences of the microhardness of the stir zone and base material are different: for the base material it is of a “V-shaped” form with a minimum of 85 HV after annealing at T = 350°C, while for the stir zone it remains constant in the range of 95 – 98 HV after annealing up to 350 – 400°C, then increases and practically coincides with the values of the microhardness of the base material. The microhardness behavior of the stir zone is explained by the fact that the effect of FSP is similar to the effect of incomplete quenching.
