| Application in various fields as an extensive a type of memory alloy – NiTi(Nitinol) alloy.With the rapid development of industrial production and information technology, at present it has been widely applied in the fields of industry, medicine and daily life. At the same time NiTi alloy products increased, and the fatigue fracture problem has been paid more a attention in the process of usage. The paper studies the fracture of materials under different grain size characteristics from a variety of grain size structure of materials. According to the rules from specific experimental data, it offers the feasible theoretical basis for the use of specific materials in the production and living.First of all, this paper introduces the digital speckle correlation method principle, and provides the calculation basis for image processing. Secondly introduces the test piece surface treatment. Mainly leads to the electrochemical and mechanical polishing method using the test combination. Under the metallographic microscope and scanning electron microscope(SEM) observed the polishing grain boundary pattern on the surface of the specimen. Finally, the NiTi alloy specimen tensile experiments got the specimen deformation image. Through the digital speckle correlation method for processing experimental images, obtained the corresponding strain data. |
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