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Liquid metal embrittlement (LME) induced quasi-brittle fracture characteristics of a 9Cr–1Mo ferritic–martensitic steel (T91) after fatigue cracking in lead–bismuth eutectic (LBE) have been investigated at various length scales. The results show that the LME fracture morphology is primarily characterized by quasi-brittle translath flat regions partially covered by nanodimples, shallow secondary cracks propagating along the martensitic lath boundaries as well as tear ridges covered by micro dimples. These diverse LME fracture features likely indicate a LME mechanism involving multiple physical processes, such as weakening induced interatomic decohesion at the crack tip and plastic shearing induced nano/micro voiding in the plastic zone.

The crack propagation rate of Type 316 stainless steel in boric acid–lithium hydroxide solutions under PWR-relevant conditions was modelled. A film rupture/dissolution/repassivation mechanism is assumed and extended to cold worked materials by including a stress-dependent bare metal dissolution current density. The chemical and electrochemical conditions within the crack are calculated by finite element calculations, an analytical expression is used for the crack-tip strain rate and the crack-tip stress is assumed equal to 2.5 times the yield stress (plane-strain). First the model was calibrated against a literature published data set. Afterwards, the influence of various variables – dissolved hydrogen, boric acid and lithium hydroxide content, stress intensity, crack length, temperature, flow rate – was studied. Finally, other published crack growth rate tests were modelled and the calculated crack growth rates were found to be in reasonable agreement with the reported ones.

The crack propagation rate of Type 304 stainless steel in diluted sulphuric acid solutions was modelled based on finite element calculations of the chemical and electrochemical conditions within the crack and an analytical expression for the crack-tip strain rate. The slip/dissolution/repassivation mechanism was assumed. The influence of various variables – dissolved oxygen, sulphuric acid content, stress intensity, crack length, temperature, flow rate, sensitization and yield strength – was studied and found to be in agreement with experimental observations. The model was calibrated against one data point. The effect of temperature on thermal conductivity, electrode reaction kinetics, equilibrium constants, yield strength and crack geometry was considered and the thermal activation energy for the crack propagation rate could almost fully be accounted for.

This article describes the calculation of the polarisation behaviour of a metal in an aqueous environment using a computational electrochemistry code based on finite elements. The corrosion system consisted of three parallel reactions (oxygen reduction, hydrogen evolution and metal dissolution), taking place in the centre at the surface of the rotating disc electrode (RDE). The selected problem is simple enough to be solved analytically, which allows verification of the finite element calculation. Simultaneously, the example is rich enough to demonstrate the potential and the advantages of finite element simulation for corrosion science and engineering. The analytical and finite element calculations were in excellent agreement. The influence of the speed of the RDE, of the bulk concentration of dissolved oxygen and of the bulk hydrogen ion concentration on the polarisation behaviour have been determined. The use of finite elements had the following specific advantages. Firstly, no prior assumption on the diffusion layer thickness had to be made. Secondly, transport by diffusion, convection and electro-migration were taken into account. Thirdly, the finite element approach is general and flexible enough to tackle more complex systems. The calculations presented here are a first step towards the finite element simulation of stress corrosion cracking of stainless steel in an aqueous nuclear environment.