# Effects of Forging Temperature and Micro-Arc Coatings on the Static/Stress Corrosion Resistance of AZ80 Magnesium Alloy

## TL;DR

This study shows how forging temperature and micro-arc coatings affect the corrosion resistance of AZ80 magnesium alloy, with MCC coatings offering the best protection.

## Contribution

The novel MCC coating structure significantly enhances static and stress corrosion resistance in AZ80 magnesium alloy.

## Key findings

- Forging at 250 °C improves baseline corrosion resistance due to refined grains and β-Mg17Al12 precipitates.
- MCC coatings outperform MAO coatings in delaying stress corrosion cracking initiation and progression.
- MCC coatings provide robust surface protection under both static and stress corrosion conditions.

## Abstract

To enhance the surface protection of exposed moving parts made from magnesium alloys, this study focuses on developing high-performance micro-arc composite (MCC) coatings on AZ80 wrought magnesium alloy substrate. AZ80 alloys were fabricated through forging at different temperatures (250 °C, 350 °C, and 450 °C) to investigate the influence of thermal deformation on substrate properties. Subsequently, micro-arc oxidation (MAO) coatings and MCC coatings were applied to the forged alloys. Comprehensive analyses—including microstructural characterization, salt spray corrosion tests, and stress corrosion cracking (SCC) evaluations—were conducted under both static and stress conditions. Among the forging temperatures, 250 °C produced substrates with refined grains and a favorable distribution of β-Mg17Al12 precipitates, resulting in improved baseline corrosion resistance. MAO coatings offered moderate protection, primarily delaying corrosion initiation and crack propagation under stress environments. Building upon this foundation, MCC coatings—fabricated by electrostatic spraying to form an inner-embedded and outer-wrapped structure over the MAO layer—demonstrated significantly superior protective performance. Under both static and stress corrosion scenarios, the MCC coatings effectively suppressed SCC initiation and progression, highlighting their potential for robust surface protection in demanding service environments.