Reason for Excessive Precipitation of Chromium Ion in 430 Stainless Steel Pot after Dry Burning

The excessive amount of chromium ion precipitation in 430 stainless steel pot after dry burning test was determined by heavy metal migration test. The reason for exceeding was analyzed by chemical composition analysis, microstructure observation, electrochemical property testing, and so on. The results show that during the dry burning, the 430 stainless steel pot was in the precipitation temperature range of chromium-rich σ phase. The chromium-rich σ phase was prone to precipitate and caused chromium depletion around it. In corrosive solutions, the electrochemical reaction occurred between the σ phase and the chromium-depleted region, led to the ionization of chromium in the chromium-depleted region and the falling off of the chromium-rich σ phase, and eventually resulted in the excessive precipitation of chromium ion.