Effect of heat treatment on corrosion resistance of WE54 alloy

AbstrAct Purpose: Poor corrosion resistance is one of the main causes to prevent magnesium alloys for wide applications. The addition of rare earth elements (RE) is an effective way to improve corrosion resistance of magnesium alloys. Heat treatment condition can also influence the corrosion behavior of magnesium alloys. The purpose of the investigation was to study the corrosion resistance of WE54 alloy after heat treatment. Design/methodology/approach: The study was conducted on WE54 alloy in the as-cast condition and after heat treatment at 250-300˚C for periods of time 4 – 96 h. Immersion test was performed using not deaerated 3.5% NaCl solution at room temperature. Specimens were placed in 3.5% NaCl solution for periods of time between one and 7 days. The dissolution rates (mg cm-2 day-1) were determined by weight loss measurements. After immersion test, the microstructure and the appearances of the corroded structure were examined by scanning electron microscopy. Findings: The corrosion rate of WE54 alloy strongly depends on heat treatment condition. WE54 alloy in the as-cast and after solution treated have similar corrosion behavior, different from that of aged specimens. The curves of corrosion rate for aged specimens were higher than that for as-cast and solution treated conditions. It was also noticed that the longer time of ageing the higher corrosion rates were observed.