In this study, the effect of fluid flow rate, surface roughness and strain level on the corrosion behavior of magnesium alloy AZ31 was characterized in a custom test bench. Specimens were prepared by mechanical polishing and subject to flow in a simulated body fluid at 37°C for 24 hrs. Compared to a specimen pre-strain of 0%, mass loss was shown to increase by approximately 6% with a specimen pre-strain of 10%. Similarly, mass loss increased by approximately 13% when the fluid flow rate was increased from 250ml/min to 500ml/min. Surface roughness had a significant influence on corrosion behavior. Compared to a specimen polished with a 1 µm diamond paste, the mass loss for a specimen polished with #600 sandpaper was 28% greater.

Magnesium is an essential element for human health and is a suitable material for bio-absorbable implant because the risk of hypermagnesemia is quite low. In recent years, a number of studies have been carried out using bioabsorbable materials for implantable scaffolds. It is desirable the device performance can be tailored to the anatomical site in which the device is implanted, so the key problem for these devices was to control the corrosion rate of magnesium. However, the effect of the blood flow over the devices on the corrosion behavior is not obvious yet. In the present study, we investigated the corrosion behavior of various specimens immersed in fluid flows. The corrosive environment was reproduced by pulsatile flow of NaCl solution representing blood flow in the human body. It was found that the corrosion behaviors of the specimens were strongly affected by the induced strain, the surface condition and the flow rate. In contrast, the change in the fluid flow characteristics such as laminar flow and turbulent flow had less strong effect on the corrosion behavior.