No abstract

Friction stir channeling (FSC) is a simple method for fabrication of a continuous, integral channel in a monolithic plate, which is carried out in a single pass. The fabricated channels can be applied in heat exchanger industry. In this study, a novel technique was introduced to produce channels in 6061 aluminum alloy which is named as Modified Friction Stir Channeling (MFSC). This technique is derived from Friction stir processing. In this technique, the tool profile and position of tool pin against work piece were designed differently from FSC process. Channels were fabricated with a very regular shape such as rectangular. Comparison between MFSC and FSC showed that fabricated channels, using MFSC process, had better properties relative to fabricated channels by FSC.

Modified friction stir channeling (MFSC) is a new approach for fabrication of a continuous, integral channel in monolithic Al plate, which is carried out in a single pass. This technique is derived from Friction Stir Processing (FSP). Tool profile and position of tool pin against work piece were designed differently from conventional Friction Stir Channeling (FSC) process. In MFSC, Fabricated channel with more regular shape than FSC process shows that the channel formation mechanism is different from FSC. So, in this study, in order to understand the formation of channel, material flow in MFSC is investigated using weakened tool pin technique. Moreover, one of the most important channel properties is width of channel. This characteristic affected the channel area and shape of the channel. Width of channel was unknown in FSC process. But in MFSC, a new region is investigated which determines the channel width.

No abstract

This study is aimed to understand the correlation between the manufacturing process-induced plastic deformation, microstructure, and corrosion behavior of a 13Cr martensitic stainless-steel tubing material (UNS S42000). Comparisons were made between the microstructure, crystallographic orientation, and corrosion performance of a texture free heat-treated sample and uniaxially tensioned samples to the elongations of 5% and 22%. Cyclic potentiodynamic polarization (CPP) tests and electrochemical impedance spectroscopy (EIS) were performed on all samples in aerated 3.5 wt.% NaCl electrolyte at room temperature. Overall, the corrosion resistance of the samples was found to decrease with increasing the deformation level. A more stable and higher corrosion potential and pitting potential values with a better stability of the passive film were derived for the non-deformed sample, whereas the 5% and 22% elongated samples exhibited lower corrosion and pitting potential values, and were characterized by having a less stable passive layer. All samples consistently revealed micro-pits formation on the lath boundaries where high concentration of chromium carbide precipitates was detected. Increasing the level of plastic strain in 13Cr stainless steel was found to enlarge the size of sensitized regions along the matrix-coarse chromium carbide precipitates interface, providing more susceptible regions to initiation and propagation of pitting.