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In situ differential thermal analysis device for evaluating high-speed phase transitions

Authors
  • Roca, Angel Sánchez1
  • Fals, Hipólito Domingo Carvajal1
  • Zoqui, Eugênio José2
  • 1 University of Oriente - UO, Manufacturing and Materials Department, School of Mechanical Engineering, Santiago de Cuba, 90400, Cuba , Santiago de Cuba (Cuba)
  • 2 University of Campinas - UNICAMP, Manufacturing and Materials Department, School of Mechanical Engineering, Campinas, SP, 13083-860, Brazil , Campinas (Brazil)
Type
Published Article
Journal
Journal of Thermal Analysis and Calorimetry
Publisher
Springer Netherlands
Publication Date
Aug 16, 2018
Volume
134
Issue
3
Pages
1589–1597
Identifiers
DOI: 10.1007/s10973-018-7629-5
Source
Springer Nature
Keywords
License
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Abstract

Thixoforming involves heating different types of alloys to the semisolid state at high heating rates and forming in die-casting machines or conventional presses. At temperatures higher than the solidus and lower than the liquidus, the mush metal behaves like a high-viscosity thixotropic material. Therefore, determining the thermodynamic behavior of the solid-to-liquid transition is paramount to control thixoforming processes. This article describes a simple, novel experimental setup based on differential thermal analysis (DTA) for analyzing the phase transitions in an alloy heated using high heating rates typical of industrial applications. A365 alloy was chosen to demonstrate the effectiveness of the method as the phase transformations for this alloy in semisolid materials (SSM) processing are well understood. Samples were heated to 750 °C using constant linear heating rates of 5, 10, 15, 20, 25, 50, 75, 100 and 125 °C min in a Norax 25 kW 8 kHz induction furnace with an Omron E5CK temperature controller. AISI 316 austenitic stainless steel was used as the inert reference. Comparison of the results of DTA using the proposed method and the results of simulation with Thermo-Calc® indicates that the proposed in situ DTA device and its method is suitable for analyzing phase transitions when high heating rates are used.

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