High temperature tensile tests of cast magnesium alloys
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AuthorCasuso Valcarce, Rodrigo
The development of new magnesium alloys is showing a promising improvement in their properties at elevated temperatures, which as it has been studied are affected adversely when these materials are subjected under this condition. This development could make magnesium alloys suitable for applications where they hadn’t been used previously, so the assessment of high temperature mechanical properties and development of new alloys is of real importance. Thereby, the testing at high temperature of these materials is required. However, the problem emerges because of their high combustion power and risk of fire when they reach their ignition temperature. Due to all arises the purpose of this work. This purpose is to design and assemble the required equipment to be able to carry out safe, reliable and repeatable tests of cast magnesium alloys at elevated temperature. In this way, the question about how this type of materials could be protected against the fire comes up. After the study of this question, it was concluded that would be necessary to protect the specimens with an inert atmosphere of argon or helium during the tests, being in this way required to perform a design of a device to maintain the specimens under this inert atmosphere and the assembly that ensures a correct working of this design with the existing equipment in the lab. The features of the existing equipment (universal testing machine, laser extensometer, and furnace) required that the device to cover the specimen and achieve the inert atmosphere should have good optical properties to allow the proper working of the laser extensometer, and also good temperature resistance due to would be subjected at high temperatures. With the help of the software “CES EDUPACK” was found the right material for this application, and the result was silica (fused). After that, was studied the shape that this material could adopt. In this case the effects that the possible shapes could have in the deformation measurements taken by the laser extensometer were analysed, the conclusion was that with a hollow cylindrical shape the measurements wouldn’t be affected, being this shape the most appropriate. The rest part concludes with the design of assembly of this device to the testing machine and thus to be able to perform hot tensile tests. This design of assembly which apparently satisfies its goal is shown in the report. Finally the work concludes that is possible to perform a design that could achieve the purpose of this work with the existing equipment. Although it is declared that its performance has to be checked in lab carrying out tests.