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Abstract <p>Samples of the industrial alloy Ti–6Al–4V in a single-phase micro-grain α state, after special thermomechanical treatment including hot rolling,—were studied by (i) mechanical tensile measurements and (ii) low-cyclic fatigue tests, without (LCF) and with exposure for 2-min dwelling at maximum stresses in the vicinity of yield strength (LCDF), and by (iii) X-ray diffractometry, (iv) scanning orientation-related and (v)&#xa0;transmission electron microscopy before and after LCF/LCDF testing. The layered arrangement of the globular α grains in the cross section of the initial samples cut out across the direction of rolling is characterized by the texture-related selection and their regular distribution in accordance with the orientation relationships of Burgers and twin orientations. Special microtextural regions with close (nearly similar) crystallographic orientations of α grains are inherited by the samples at their LCF investigation. In the fractographic study, it was found that the fracture in the course of LCF tests without (the mentioned) exposure of fine-grained α microstructure, so,—this fracture occurs mainly according to the cell-facet grain boundary mechanism. The dimpling relief of the surface of fracture correlates with the sizes and rounded shape of the primary α grains. LCDF with the dwell exposure for 2 min, at the same value of stresses (0.96–0.97σ<sub>0.2</sub>) leads to a decrease by 30 times in the number of cycles to sample failure. At the same time, the dominant mechanism of the fatigue failure of the samples radically changes to the mechanism of their fracturing through mainly the macrotextural zones with a close orientation of α grains that is being formed due to the micro-fluidity under load along prismatic and pyramidal planes of easy sliding.</p>

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Structure-Phase Transformations and Crystallographic Texture in the Industrial Alloy Ti–6Al–4V with Globular Morphology of α-Phase Grains. Low-Cycle Dwell Fatigue on Samples Cut across the Rolling Direction

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • V. G. Pushin,
  • D. Yu. Rasposienko,
  • N. N. Kuranova,
  • V. V. Makarov,
  • A. A. Markin,
  • O. B. Naimark,
  • A. E. Svirid,
  • A. N. Uksusnikov,
  • Yu. M. Ustyugov

摘要

Abstract

Samples of the industrial alloy Ti–6Al–4V in a single-phase micro-grain α state, after special thermomechanical treatment including hot rolling,—were studied by (i) mechanical tensile measurements and (ii) low-cyclic fatigue tests, without (LCF) and with exposure for 2-min dwelling at maximum stresses in the vicinity of yield strength (LCDF), and by (iii) X-ray diffractometry, (iv) scanning orientation-related and (v) transmission electron microscopy before and after LCF/LCDF testing. The layered arrangement of the globular α grains in the cross section of the initial samples cut out across the direction of rolling is characterized by the texture-related selection and their regular distribution in accordance with the orientation relationships of Burgers and twin orientations. Special microtextural regions with close (nearly similar) crystallographic orientations of α grains are inherited by the samples at their LCF investigation. In the fractographic study, it was found that the fracture in the course of LCF tests without (the mentioned) exposure of fine-grained α microstructure, so,—this fracture occurs mainly according to the cell-facet grain boundary mechanism. The dimpling relief of the surface of fracture correlates with the sizes and rounded shape of the primary α grains. LCDF with the dwell exposure for 2 min, at the same value of stresses (0.96–0.97σ0.2) leads to a decrease by 30 times in the number of cycles to sample failure. At the same time, the dominant mechanism of the fatigue failure of the samples radically changes to the mechanism of their fracturing through mainly the macrotextural zones with a close orientation of α grains that is being formed due to the micro-fluidity under load along prismatic and pyramidal planes of easy sliding.