Susceptibility to delayed fracture of alpha-beta titanium alloy in fluoride solutions

Ken'Ichi Yokoyama, Toshio Ogawa, Kenzo Asaoka, Jun'Ichi Sakai

    Research output: Contribution to journalArticle

    15 Citations (Scopus)

    Abstract

    The susceptibility to delayed fracture of the alpha-beta titanium alloy Ti-6Al-4V has been investigated in acidic and neutral fluoride solutions at room temperature. The time to fracture decreased with increasing applied stress in 2.0% and 0.2% acidulated phosphate fluoride (APF) solutions at pH 5.0. The time to fracture in the 2.0% APF solution was shorter than that in the 0.2% APF solution, although at an applied stress higher than 1000 MPa, the times to fracture were almost the same in both the solutions. For immersion in the 0.2% APF solution, when the applied stress was lower than 700 MPa, delayed fracture did not occur within 1000 h. The fracture surface of specimens immersed in the 2.0% APF solution exhibited brittleness associated with hydrogen absorption, while that in the 0.2% APF solution was ductile and characterized macroscopically as having a cup-cone morphology. The amounts of hydrogen absorbed in 2.0% and 0.2% APF solutions for 24 h were approximately 200 and 30 mass ppm, respectively. As the immersion time increased, the amount of hydrogen absorbed in the 2.0% APF solution increased, whereas that in the 0.2% APF solution hardly increased. In neutral 2.0% and 0.2% NaF solutions, the delayed fracture did not occur within 1000 h, although general corrosion was observed. These results indicate that the susceptibility to delayed fracture of alpha-beta titanium alloy, compared with those of the alpha titanium and beta titanium alloy reported previously, is low in acidic and neutral fluoride solutions.

    Original languageEnglish
    Pages (from-to)1778-1793
    Number of pages16
    JournalCorrosion Science
    Volume47
    Issue number7
    DOIs
    Publication statusPublished - 2005 Jul

      Fingerprint

    Keywords

    • Corrosion
    • Delayed fracture
    • Fluorides
    • Hydrogen embrittlement
    • Ti-6Al-4V alloy

    ASJC Scopus subject areas

    • Materials Science(all)
    • Metals and Alloys

    Cite this