Paula Fernanda da Silva FarinaUniversity of Campinas | UNICAMP · Departamento de Manufatura e Materiais (DEMM)
Paula Fernanda da Silva Farina
Doctor of Engineering
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21
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Publications (21)
The allotropic transformation, characteristic of cobalt-based alloys, occurs at around 970 ºC in Co-28Cr-6Mo alloys. When subjected to fast cooling, such alloys can maintain the high temperature cubic centered phase at room temperature, resulting in a CFC metastable matrix. This metastable condition leads to a nucleation of the hexagonal phase (the...
Co-based alloys have been used as biomedical materials in the cast or wrought form for more than fifty years. Since then, studies have been performed to better understand the high mechanical strength and wear resistance of these alloys. Recently, additive manufacturing techniques, such as laser-powder bed fusion (L-PBF), are being employed to produ...
The wear resistance of the biomedical low-carbon Co-28Cr-6Mo (wt.-%) alloy is mostly determined by the onset and magnitude of the face-centered cubic to hexagonal close-packed deformation-induced martensitic phase transformation. In metal-on-metal joint bearings, local plastic deformation occurs on the surface and in the subsurface regions. This ca...
Brazilian heavy-haul railway companies have drawn extensive research in the last years for developing solutions that can make the operation in this area more efficient and safer, such as friction management, the use of new mechanical assemblies, and the use of new materials for wheels and rails. Another solution implemented is increasing the weight...
This article focused on the microstructure characterization and residual stress measurements of the flange from classes D and C railway wheels (called 7D and 7C steel, respectively) to contribute with the residual stress level on new forged wheels flange area. A correlation with the hardness was conducted. The residual stress was measured in three...
Wear and contact fatigue are the main problems that reduce the durability of the rail and wheels. Pearlitic and bainitic microstructures have been studied over the years to obtain steel with higher mechanical properties, minimizing the wear and fatigue defects. However, the studies have not yet consistently confirmed whether bainite is a better alt...
The Heavy-Haul railroad wheels started to use higher wear resistance steels microalloyed with niobium, vanadium, and molybdenum [1]. During continuous cooling, these elements depress the temperature of the pearlite formation, producing smaller interlamellar spacing that increases the hardness of the steel, besides to favor the precipitation hardeni...
The influence of strain-induced martensitic transformation on the mechanical properties of a Co–28Cr–6Mo alloy produced using the direct metal laser sintering additive manufacturing technique was analyzed. Both the as-built and solution heat-treated (ST) specimens were subjected to conventional tensile tests. Furthermore, X-ray diffraction spectra...
The effects of cryogenic and stress relief treatments on temper carbide precipitation in the cold work tool steel AISI D2 were studied. For the cryogenic treatment the temperature was - 196°C and the holding time was 2, 24 or 30 h. The stress relief heat treatment was carried at 130°C/ 90 min, when applied. All specimens were compared to a standard...
Recent literature has shown several papers dealing with cryogenic treatments of tool steels. Most of them see an improvement in wear resistance supposedly due to microstructural modifications that occur at cryogenic temperatures. Cryogenic treatments are supposed to modify the way secondary carbides precipitate, obtaining a finer and more homogeneo...
Magnetic Barkhausen noise (MBN) was used to characterize the progress of austenite to martensite phase transformation while cooling steel specimens, using a conventional Barkhausen noise emission setup stimulated by an alternating magnetic field. The phase transformation was also followed by electrical resistivity measurements and by optical and sc...
The use of magnetic Barkhausen (MBN) noise methods to detect the austenite to martensite phase transformation during cooling of steel specimens was explored, using three different configurations: conventional Barkhausen noise emission stimulated by an alternating magnetic field, the Okamura method, that measures magnetic noise emission under a fixe...
The effects of low temperature isothermal treatments on a quenched AISI D2 tool steel was studied using Barkhausen Noise, X-ray diffraction, dilatometry and optical and electronic microscopy. The specimens were austenitized at 1040 degrees C and quenched in oil. The isothermal treatments involved immersion in hot oil baths at 80 degrees or 130 degr...
Recent literature has shown several papers dealing with cryogenic treatments of tool steels. Most of them see an improvement in wear resistance supposedly due to microstructural modifications that occur at cryogenic temperatures. Cryogenic treatments are supposed to modify the way secondary carbides precipitate, obtaining a finer and more homogeneo...
The effects of volume fraction and morphology of niobium carbides in Nb-alloyed high speed steels were studied in front of abrasion. After heat treatment of quench and temper, to obtain the maximum hardness, the alloys were submitted to abrasive tests in a dry rubber wheel machine with hematite as abrasive. It was used the load of 130N, 200 rpm and...
The aim of this work is to study and evaluate the property of fracture toughness (KICV) of an AISI M3:2 high speed tool steel produced by a Powder Metallurgy technique. The P/M M3:2 high speed steel was manufactured by cold uniaxial compaction of irregular water atomized powders with and without 0.3% of carbon followed by sintering under vacuum pro...
Effect of Stress Relief on the Amount of Retained Austenite After Cryogenic Treatment and on the Wear Resistance of a Tool Steel
P. F. S. Farina(1)*, R. V. Martin(2), R. A. Mesquita(3), C. A. Barbosa(3) and H. Goldenstein(1)
(1) Laboratório de Transformações de Fases, Departamento de Eng. Metalúrgica e de Materiais, EPUSP, e-mail: pfsilva2@gmail.c...