You are being redirected because this document is part of your ASTM Compass® subscription.
    This document is part of your ASTM Compass® subscription.

    If you are an ASTM Compass Subscriber and this document is part of your subscription, you can access it for free at ASTM Compass
    STP1263

    Thermal Mechanical Fatigue Crack Growth in Titanium Alloys: Experiments and Modelling

    Published: 01 January 1996


      Format Pages Price  
    PDF (1016K) 23 $25   ADD TO CART
    Complete Source PDF (8.8M) 380 $87   ADD TO CART

    Cite this document

    X Add email address send
    X
      .RIS For RefWorks, EndNote, ProCite, Reference Manager, Zoteo, and many others.   .DOCX For Microsoft Word


    Abstract

    Strain controlled thermal-mechanical fatigue crack growth (TMFCG) tests were conducted on two titanium alloys, namely Ti-6A1-4V and Ti-6Al-2Sn-4Zr-6Mo, to evaluate the effect of phase angle between strain and temperature on the TMFCG rates. Three fracture mechanics parameters were used to correlate the data: the ΔK, ΔKe and ΔKeff. A fractographic study of the specimens tested under TMF was carried-out to identify the mechanisms responsible for cracking in these two titanium alloys. Hence, specimens tested under in-phase (εmax at Tmax), out-of-phase (εmin at Tmax) and counter-clockwise diamond (90° out-of-phase) conditions were compared to specimens tested under isothermal conditions (Tmin and Tmax) for different ΔKeff levels. The dominant TMF cracking mechanisms were mechanical fatigue (crack tip plasticity) and oxygen-induced embrittlement. The ΔKeff was found to be the only parameter to properly correlate all the data obtained under various testing conditions. A model is developed to predict the TMFCG rates based solely on isothermal data. The model uses a linear summation of the contributions to crack growth of the two dominant mechanisms which are active at the minimum and maximum temperature of the cycle. A discussion on the applicability of the model to predict the fatigue lives of actual components is discussed.

    Keywords:

    Titanium alloys, crack growth, oxygen embrittlement, fatigue life prediction, TMF


    Author Information:

    Dai, J
    Stress Engineer, Bombardier/Canadair, Ville St-Laurent, Québec

    Marchand, NJ
    R & D Engineer, AMRA Technologies, Montreal, Quebec

    Hongoh, M
    Project Engineer, Stress Analysis Group, Pratt and Whitney Canada, Longueuil,


    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP16454S