Modeling for fracture in materials under long-term static creep loading and neutron irradiation. Part 1. A physico-mechanical model

Abstract

The paper presents a physico-mechanical model for predicting creep rupture in neutron-irradiated materials. The model is based on the approach whereby damage is described as voids on grain boundaries. The equations for void nucleation and growth which were proposed by the authors earlier are augmented to include neutron irradiation of material. Constitutive equations are derived to describe viscoplastic deformation of material including void propagation. A criterion for plastic stability of a unit cell is employed as a fracture criterion.

A method for predicting fracture resistance of material in cyclic loading under viscoelastoplastic deformation and neutron irradiation conditions

“…The structure operation time is, for example, 2 10 5 ⋅ h. The inelastic strain range in cycles is the same. Based on [14][15][16], we have ε ε…”

“…This relation can be derived using stress rupture ductility data for a material irradiated with a neutron flux Φ and pre-irradiated with neutron fluence F [14][15][16]. Figure 2 shows schematically the dependence of creep rupture strength σ and stress rupture ductility ε f on time to failure t f together with the transgranular and intergranular fracture regions.…”

“…can be determined from the functions ε f f t ( ) derived by means of a physical-mechanical model of intergranular fracture [14][15][16]. Consider prediction of fatigue curves by the Coffin-Manson equation [12,13]:…”

“…h −1 ) [21]. Let us assess ξ * by using the proposed method and data provided in [14][15][16]. Figure 8 shows the calculated ε ξ f ( ) function at T =°600 C for steels of Kh18N9 and Kh18N10T grades in the initial state (Φ = 0).…”

Modeling for fracture in materials under long-term static creep loading and neutron irradiation. Part 3. Crack growth rate prediction for austenitic materials

“…Fundamentals. Using the model proposed in [12], the crack growth rate in an irradiated material ( ) dL d irr τ can be determined provided that the crack growth rate in the unirradiated material is known. The procedure of the ( ) dL d irr τ determination is based on the following principles.…”