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Preliminary Structures Assessment of Some TRIP Steels

Pantilimon Mircea Cristian, Berbecaru Andrei-Constantin, Coman George, Sohaciu Mirela G., Dumitrescu Ruxandra Elena, Ciucă Sorin, Gherghescu Ioana-Arina, Predescu Cristian

Archives of Metallurgy and Materials

2023

Vol. 68, iss. 2

491--498

Automotive industry is constantly interested in building cars made of light and high strength parts in order to reduce the emission levels, the fuel consumption and minimize the effects of a car crash. Some parts may be made of lighter materials, but the steel ones must compensate the strength needed for the car body. Research is made for finding new materials showing high strength combined with high ductility. Among them, transformation - induced - plasticity steels are of great interest, efforts being made to improve their characteristics. A new composition of such a steel is presented, its features being compared with those of three other steels of the same class and category. Optical microscopy at different magnifications is performed, together with Vickers hardness test. Structural particularities are found for each tested steel, justified by their own chemical compositions. The new steel reveals important characteristics: besides the mainly bainitic structure, it has both larger ferritic areas and amounts of retained austenite, making him proper for further study.

Research on the Degradation Process of Railway Rails Due to Lifespan Exceeding

Berbecaru Andrei-Constantin, Coman George, Ciucă Sorin, Gherghescu Ioana-Arina, Sohaciu Mirela, Grădinaru Catalin, Predescu Cristian

Archives of Metallurgy and Materials

2022

Vol. 67, iss. 2

535--540

The paper presents the impact of exceeding the railway rails lifespan which usually causes a railway structural failure, thus an accident. The research highlights the rails’s high degradation, especially on the running area, consisting in 60-70% weight loss by advanced wear of the rail, followed by fatigue fracture caused by alternating cyclic stresses that initiates the crack and also by tensile stresses resulting in the crack growth. The chemical composition, structural and mechanical properties were analyzed in order to establish the causes that led to the railway rails rupture.

Photocatalytic TiO2 Nanostructures Developed on the Grade 2 Ti Material

Tarcea Claudia I., Pantilimon Cristian Mircea, Coman George, Turcanu Andreea A., Predescu Andra Mihaela, Matei Ecaterina, Berbecaru Andrei-Constantin, Predescu Cristian

Archives of Metallurgy and Materials

2022

Vol. 67, iss. 3

1079--1084

The research focused on TiO2 nanostructures environmental applications due to the special characteristics that displayed degradation of the organic compounds into environmentally friendly products through exposure to UV light. The protocol behind obtaining the nanostructures involved the use of a Ti material exposed to alkaline treatment and advanced oxidation using NaOH solution and acetone. These studied nanostructures were analyzed extensively by using methods such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) for characterizing the elements, compounds and morphological properties of the material. These differences in morphology is attributed to different NaOH solution concentrations. The Ti sheets were immersed into NaOH and acetone mixed solutions for 72 hours. The best results were recorded by using 30% NaOH solution. After obtaining the 3D structures, which improve specific surface and contact area with the environment, the samples were tested under UV light in order to degrade methylene blue in order to determine their photocatalytic performance.