Effect of Surface Aluminizing on the Zinc Corrosion Resistance of Fe-20Cr-5B-3Al Alloy

TL;DR

Surface aluminizing improves the corrosion resistance of an Fe-20Cr-5B-3Al alloy in liquid zinc by transforming its surface microstructure.

Contribution

The study demonstrates that aluminizing treatment enhances corrosion resistance by converting α-Fe to Fe2Al5.

Findings

Aluminizing transforms α-Fe into Fe2Al5, which resists corrosion better.

The Fe2B phase breaks into finer structures after treatment.

Aluminized alloy shows significantly reduced corrosion rate in liquid zinc.

Abstract

This study systematically investigates the effect of surface aluminizing treatment on the microstructure of Fe-20Cr-5B-3Al alloy and its corrosion behavior in liquid zinc. Aluminizing treatment was performed using the powder pack method with NH4Cl (5 wt.%) as a catalyst. Aluminide layers were prepared on the surface of the Fe-20Cr-5B-3Al alloy, and the microstructure of the aluminide layer was observed and analyzed. The corrosion performance of the alloy in liquid zinc was compared before and after aluminizing treatment in a 128 h corrosion test. The results show that after aluminizing treatment, the α-Fe phase on the alloy surface transforms into the Fe2Al5 phase, while the original Fe2B phase breaks into finer structures that disperse over the Fe2Al5 phase. The Cr2B phase is not affected and maintains its structural integrity. After 128 h of exposure to liquid zinc, although the alloy exhibited good corrosion resistance in liquid zinc, the α-Fe phase was still preferentially corroded, with zinc liquid infiltrating along the α-Fe phase toward the interior. In contrast, after aluminizing treatment, the transformation of α-Fe into Fe2Al5, which has excellent corrosion resistance, significantly reduces the corrosion rate and enhances the alloy’s resistance to liquid zinc corrosion.

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