Processes of physical treatment of stainless steels obtained by additive manufacturing

With a vista of available stainless steel grades at our disposal, it is possible to manufacture items for a wide range of industries. These include chemicals production, medicine, and pharmacology, aerospace, power engineering, etc. Stainless steels are widely used mostly due to their unique property set, both mechanical and physicochemical ones, achieved by alloying various components. Stainless steel workpieces are usually obtained by melting, alloying, casting, and subsequent rolling to the desired shape. The experience in the study of the microstructure and processes of physical treatment of steel accumulated to the present day mainly concerns the machinability (blade, abrasive, laser, etc.) of such steels obtained by conventional techniques. Meanwhile, approaches to the production of workpieces from stainless steels by additive manufacturing (AM) methods are actively developing. In their turn, additive manufacturing technologies allow for producing workpieces that are structurally as close as possible to the final product shape. However, the use of AM workpieces in the manufacturing of functional products brings questions related to the study of the treatability of such steels by mechanical and physical processes to achieve a wide range of functional characteristics. This article discusses the issues of treatability and the characteristics and properties of stainless steels obtained by AM

Wear resistance and friction analysis of Ti6Al4V cylindrical ball-burnished specimens with and without vibration assistance

The objective of the research is to analyze the impact of the ultrasonic vibration assistance on the wear resistance due to the topography enhancement caused on Ti6Al4V cylindrical samples after surface modification through a ball burnishing process. The process parameters considered for this study are the burnishing force, the number of passes, and the addition of a 40 kHz ultrasonic assistance, which are thought to enhance the surface topography and increase the hardener effect in terms of depth. A complete screening design of 3 factors was performed, revealing that the number of passes and the vibration assistance are the most important parameters for minimizing the wear volume loss, being 170 N of burnishing force, 3 passes, and the addition of the vibration assistance as the best combination found. However, no significant difference in the friction force was observed. The topography results show that there is a decrease in the average roughness from 1.50 to 0.45 µm with optimal burnishing conditions. It was also analyzed the microstructure originated after the turning, the conventional ball burnishing, and the vibration-assisted ball burnishing, being the last optimal in terms of depth affectation to the microstructure. Therefore, these results confirm an improvement in terms of wear enhancement, friction reduction, and topography results when vibration assistance is added to a conventional ball burnishing process.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version