Origin of flakes on stainless steel heater

The corrosion resistance of AISI 321 stainless steel depends on the formation of thin and compact Cr3O3 oxide layer that protects the steel surface. But sometimes anomalies appear, that enable formation of the protective layer and the steel becomes sensitive to oxidation at elevated temperatures. In such a case, the oxide layer is not compact enough and the oxide fall off the surface. Presented are investigations of flakes on the surface of stainless steel heaters for household application. The flakes appeared during the first short time heating test of the heater. Analyses revealed that the flakes on the heaters originated from the hot rolling process. The rolled in hot cracks enabled the formation of the flakes on the surface of the heater. (c) 2006 Elsevier Ltd. All rights reserved.