Showing 2 results for Roughness.
M. Barjesteh, K. Zangeneh Madar, S. M. Abbasi, K. Shirvani,
Volume 38, Issue 2 (9-2019)
Abstract
In this study, the effect of platinum-aluminide coating parameters on surface roughness of nickel-based superalloy Rene®80 was evaluated. For this purpose, different thicknesses of Pt-layer (2, 4, 6 and 8µm) were plated on the Samples. Then diffusion aluminide coating in two types, high tempeature-low activity and low temperature-high activity was performed. The results of structural investigations by scanning electron microscope and X-Ray diffraction indicated a three-zone structure of coating in all thicknesses of platinum layer, as well as in the two methods of aluminizing. Surface roughness of coatings was measured in three steps: 1-after Pt plating, 2-after Pt diffusion, and 3-after aluminizing and final aging. The results showed that the thickness of Pt and the final thickness of the coating directly affected the surface roughness. The minimum surface roughness was created by high temperature low activity with 2µ of Pt-layer (2.6μm) and the maximum of surface roughness was obtained in low-temperature high activity with 8µ of the Pt-layer (8.8 μm).
A. Mohammadi, B. Niroumand, A. Saboori,
Volume 40, Issue 4 (3-2022)
Abstract
Electron beam melting (EBM) is among the modern additive manufacturing processes whereby metal powders are selectively melted to produce very complicated components with superior mechanical properties. In this study, microstructure, hardness, and surface roughness of EBM fabricated Ti6Al4V samples were characterized. The results showed that the microstructure consisted of epitaxially-grown primary columnar β phase transformed to basketweave and Widmanstatten-type α phase during the subsequent rapid cooling. Martensitic needle-type α phase was also observed on the surfaces of the specimens. It was shown that higher parts of the sample had finer microstructures than the lower parts reaching to less than 340 nm in average thickness of the α layers due to distancing from the hot build platform rendering less opportunity for diffusional β → α+β transformation. The porosity content of the samples was lower than that of some other additive manufacturing processes. Vickers micro-hardness of the samples was measured to be around 337 HV which was higher than those reported for other additive manufacturing processes of the alloy.
