A semi-phenomenological dynamics model for full-life predictions of stress corrosion cracking

Abstract

A semi-phenomenological model mimicking the full-time process of stress corrosion cracking (SCC) is proposed, and its attractive characteristics can be summarised as follows. Firstly, the role played by the hydrostatic pressure gradient at a crack tip in anodic dissolution is centralised by the proposed partial differential equation system, so as to formulate the interplay of load and corrosion in a mechanistic manner. As a result, the model can naturally reproduce the repeated film rupture mechanism that is believed central to general SCC phenomena. Secondly, the model implementation is extremely efficient, outputting a full-life SCC prediction within a few seconds on a normal laptop computer. Thirdly, a general rule for model calibration is introduced against limited experimental data, enabling its predictability over SCC indices that are not experimentally trackable. The efficacy and the generality of the proposed model are examined with three SCC scenarios, including (a) Inconel 600 alloys in nuclear pipelines, (b) stainless steels in oil pipelines, and (c) magnesium alloys used as structural materials in blood vessels. It is shown that SCC indices such as the SCC incubation period, which may be too long to be experimentally measured, can be quickly predicted with the present model after being calibrated.