STP1256

    CTOD (δ5) Estimate of Mis-Matched Joints Using the ETM-MM Procedure

    Published: Jan 1995


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    Abstract

    Defect assessment analyses of engineering structures require information on the elastic-plastic crack driving force. The Engineering Treatment Model (ETM) has been developed at the GKSS Research Center to estimate the crack tip opening displacement CTOD (δ5) and the J-integral for homogeneous specimens. When the plasticity properties of base and weld metals are different, which is referred to as weld strength mis-match, the defect assessment procedures need to be modified accordingly. Therefore, the ETM has recently been extended (ETM-MM) to predict the CTOD for tension loaded wide plates with transverse strength mis-matched welds containing through thickness cracks parallel to the weld / base metal interface, in the middle of the weld by finite element calculations and analytical considerations.

    This paper presents the comparison between the estimates of the ETM-MM procedure and the experimental results of as-welded (AW) and stress relieved (SR) highly overmatched weld CCT specimens. The ETM-MM predictions have been obtained using the yield stress (σ0) and strain hardening exponent (n) data approximated from the true ((σ0t, nt) and the engineering (σ0e, ne) stress-strain curves of the base and eight overmatched weld metals. The ETM-MM procedure generally provides very good estimates; however, it always yields conservative estimates of the CTOD (δ5) for all eight CCT panels with the use σ0e and ne data. On the other hand, the use of σ0t and nt values provides a better agreement with the experimental results for a large range of CTOD (δ5) cases.

    Keywords:

    Weld, Strength Mis-match, CTOD(δ, 5, ), Engineering Treatment Model (ETM), Wide plates, Limit load, Defect assessment


    Author Information:

    Hornet, P
    GKSS Research Center Geesthacht, Institute of Materials Research, Geesthacht,

    Koçak, M
    GKSS Research Center Geesthacht, Institute of Materials Research, Geesthacht,

    Hao, S
    GKSS Research Center Geesthacht, Institute of Materials Research, Geesthacht,

    Cornec, A
    GKSS Research Center Geesthacht, Institute of Materials Research, Geesthacht,

    Schwalbe, K-H
    GKSS Research Center Geesthacht, Institute of Materials Research, Geesthacht,


    Paper ID: STP16393S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP16393S


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