Continuum damage mechanics modelling of high temperature deformation and failure in a pipe weldment

Abstract

Predictions have been made of the deformation and failure history of a pipe weldment using a finite element creep continuum damage mechanics model, which incorporates the characteristic material properties of the parent metal, the weld metal and heat-affected zone microstructures of the weldment. It is shown that the computer predictions are in close agreement with the results of large-scale pressure vessel tests, provided that the material characterization is carried out correctly, and that the constitutive equations which control the evolution of creep strain and damage, represent the dominant physical mechanisms present.

High-temperature creep rupture of low alloy ferritic steel butt-welded pipes subjected to combined internal pressure and end loadings

“…CDM-based creep analyses of the butt-welded low alloy ferritic steel pipes have been carried out by Hayhurst & Perrin (1995) to overcome two major shortcomings of the pioneering work carried out by Hall & Hayhurst (1991). These are firstly, the neglect of the Type IV region of the weldment; and, secondly the deficiencies of using a single damage state variable.…”

“…In an attempt to overcome this shortcoming, Hall & Hayhurst (1991) developed a continuum damage mechanics (CDM) based finite element (FE) solver, DAMAGE XX, which incorporates the physics of the creep deformation and rupture of the individual phases of the weld materials. This approach has been shown to predict successfully the deformation, damage and failure history of the full-size pressure vessel weldment tests of Coleman et al (1985).…”

Thickness and multi-axial stress creep rupture criteria of the Type IV component of a ferritic steel weld

“…Similar ideas have been used by Cane (1981) to express the damage rate evolution equation in a form which may be integrated for both time and damage variables to yield the isochronous rupture locus in the normalised stress space where is the uni-axial normalising stress. and Hayhurst (1991) have made the equivalence between Cane's formulation and the formulation of Hayhurst (1972) in terms of the α parameter he used to describe the isochronous rupture locus.…”

“…Hall and Hayhurst (1991) accurately predicted the deformation of a full-scale butt-welded pipe that had been tested by Coleman et al (1985). The CDM model included weld, HAZ, and parent material but neglected the presence of the Type IV zone at 565PP o C. Fusion boundary failure was predicted to take place at the correct time in the weld material adjacent to the HAZ.…”

“…Detailed systematic Continuum Damage Mechanics (CDM) analyses of ferritic steel weldments, carried out using DAMAGE XX, have been pioneered by Hall and Hayhurst (1991) and later developed by Wang and Hayhurst (1994). Hall and Hayhurst (1991) accurately predicted the deformation of a full-scale butt-welded pipe that had been tested by Coleman et al (1985).…”