PSI - Issue 69

Roman Karelin et al. / Procedia Structural Integrity 69 (2025) 35–40

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3.2. Structural-phase state of obtained NiTi tubes The results of the study of structural-phase state of obtained NiTi tubes depending on the pass number are presented in Figures 2 and 3.

Fig. 2. X-ray diffraction patterns of NiTi SMA seamless tubes depending on the screw rolling pass number.

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Fig. 3. Images of the structure of NiTi SMA seamless tubes depending on the screw rolling pass number. Optical microscopy.

From the results of the XRD analysis, it can be concluded that plugging of the NiTi shell does not lead to a noticeable change in the phase composition of the alloy at room temperature. Regardless of the sample number, the phase composition consists of a mixture of the R-phase and B2-austenite. No noticeable tendency to a sharp shift in the position of the peaks of the martensite lines is also defined. The observed picture is typical for high-temperature thermomechanical treatment of titanium nickelide.