Analyzing the Characteristics of the Cavity Nucleation, Growth and Coalescence Mechanism of 9Cr-1Mo-VNb Steel (P91) Steel

Abstract

Abstract. Creep damage is one of the serious problems for the high temperature industries and computational approach (such as continuum damage mechanics) has been developed and used, complementary to the experimental approach, to assist safe operation. However, there are no ready creep damage constitutive equations to be used for predicting the lifetime for this type of alloy, particularly for low stress. This paper presents an analysis of the cavity nucleation, growth and coalescence mechanism of 9Cr-1Mo-VNb steel (P91 type) under high and low stress levels and multi-axial stress state.

Damage modelling: the current state and the latest progress on the development of creep damage constitutive equations for high Cr steels

“…The change of the stress exponent value n in Norton power law indicates a change of creep deformation mechanism and possible the creep damage mechanism [4][5][6][7][8]. General speaking, that the creep deformation under lower stress is of diffusional and the void nucleation is OPEN ACCESS controlled by the maximum shear stress; which is in line with the general understanding reported by Miannay [6].…”

“…Preliminary literature review of the creep deformation mechanisms and creep damage mechanism for parent metals has been conducted and reported [7,8]. This paper expands the literature review on the creep damage constitutive equations developed and/or used for high Cr steels [16] paying more attention to the cavity nucleation and growth.…”

“…A void growth model considering combined mechanism of diffusion and power law creep deformation under constrained condition for the void growth, and derived the void growth rate equations for spherical and crack-like voids was proposed in [37]. The void growth simulation program incorporating the void growth rate equations was also developed [7]. The void growth equations for the spherical and the crack-like voids are expressed by the following equations for spherical and crack-like void, respectively; Void initiation period, t i is expressed by the next equation.…”