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Microstructure, mechanical properties and corrosion behavior of friction stir processed AA2014 alloy

Satyanarayana M. V. N. V., Kumar Adepu, Jain Vikram Kumar S., Kumar Rahul, Mishra Sushil

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 1

art. no. e43, 2023

In the present study, a large-area stir zone (SZ) was fabricated in AA2014 alloy using multi-pass friction stir processing (FSP) with pin overlapping. The microstructure evolution, crystallographic texture, precipitation phenomenon, and tensile behavior were studied and reported. The microstructure of the large-area SZ consists of equiaxed fine grains with a high density of high angle boundaries caused by dynamic recovery (DRV) and continuous-dynamic recrystallization (C-DRX), and the grain refining has been uniform in each overlapping pass (the grain size within 4-7 μm range). The material flow around the pin caused by the stirring action of the tool contributed to the creation of a strong Brass-{110}<112>and A-{110}<111>components in the first pass of SZ. Unlike first pass SZ, the second to fifth-pass SZ presents Copper-{112}<111>and Cube- {001}<100>components due to an increase of heat input by the shoulder to participate multiple times on each overlapping SZ. The hardness and strength of the FSP sample were found to be lowered relative to a base metal. Simultaneously, the SZ ductility increased after FSP by 155% due to the material softening and dissolution of Al2Cu precipitates in the SZ. Kocks-Mecking plots of the BM and FSP samples witnessed the Stage-III of work-hardening behavior. The fine-grain structure and precipitation phenomenon in the FSP sample resulted in better corrosion resistance than the base metal.

A review of the importance of synchrophasor technology, smart grid, and applications

Baba Maveeya, Nor Nursyarizal B. M., Sheikh Aman, Nowakowski Grzegorz, Masood Faisal, Rehman Masood, Irfan Muhammad, Arefin Ahmed Amirul, Kumar Rahul, Baba A. Momin

Bulletin of the Polish Academy of Sciences. Technical Sciences

2022

Vol. 70, nr 6

art. no. e143826

The electrical network is a man-made complex network that makes it difficult to monitor and control the power system with traditional monitoring devices. Traditional devices have some limitations in real-time synchronization monitoring which leads to unwanted behavior and causes new challenges in the operation and control of the power systems. A Phasor measurement unit (PMU) is an advanced metering device that provides an accurate real-time and synchronized measurement of the voltage and current waveforms of the buses in which the PMU devices are directly connected in the grid station. The device is connected to the busbars of the power grid in the electrical distribution and transmission systems and provides time-synchronized measurement with the help of the Global Positioning System (GPS). However, the implementation and maintenance cost of the device is not bearable for the electrical utilities. Therefore, in recent work, many optimization approaches have been developed to overcome optimal placement of PMU problems to reduce the overall cost by providing complete electrical network observability with a minimal number of PMUs. This research paper reviews the importance of PMU for the modern electrical power system, the architecture of PMU, the differences between PMU, micro-PMU, SCADA, and smart grid (SG) relation with PMU, the sinusoidal waveform, and its phasor representation, and finally a list of PMU applications. The applications of PMU are widely involved in the operation of power systems ranging from power system control and monitor, distribution grid control, load shedding control and analyses, and state estimation which shows the importance of PMU for the modern world.