Study On Corrosion Behavior Of Hastelloy B-3 And C-276 In HCl

Hydrochloric acid method purification is currently the most efficient and environmental protection technology of making Al2O3 from fly ash in power plant. The medium environment is the high concentration HC l with 2%~5% oxidative ions(Fe3+ and C u2+) at high temperature, and it is are highly corrosive. Hastelloy B-3 and C-276 have good corrosion resistance in reducing acid, such as HC l. Industrially pure titanium TA1 have good corrosion resistance in HCl with oxidative ions.This paper studies the effect of heat treatment on microstructure, mechanical properties and corrosion resistance of Hastelloy B-3 and C-276. We study the corrosion behavior of Hastelloy B-3 in different Service environment(hydrochloric acid concentration, temperature, oxidizing ion concentration), and compared with TA1. Through that we explore the effects of environmental facto rs on the corrosion mechanism and provide the data support and theoretical basis for developing the new alloy to meet the corrosion resistance of hydrochloric acid method purification Al2O3 al oy.After solution treatment treatment within the range of 1040 ℃ to 1200 ℃, Hastelloy B-3 and C-276’s tensile strength decreased, plasticity gradually increased with the increase of solution temperature. The most solid solution temperature is 1150℃.After 1150×0.5h solution treatment, the most carbide dissolution of Hastelloy B-3 and C-276 is dissolved, and a few M6 C phases is left. The corrosion resistance of materials in hydrochloric acid obviously increases, and the corrosion rate decreases.With the increasing of HC l concentration or temperature, the corrosion rate of Hastelloy B-3, C-276 and TA1 increases. At the same medium conditions, corrosion rate from high to low order as: TA1, Hastelloy C- 276, Hastelloy B-3. After adding Fe3+, the corrosion rate of Hastelloy B-3 and C-276 increases significantly, and accompanied by pitting corrosion. The corrosion rate of TA1 decreases sharply, and basically close to zero. And with the change of Fe3+, the corrosion rate basically unchanged. Under s ame medium conditions, corrosion rate from high to low order as : Hastelloy B-3,Hastelloy C-276,TA1. Effects of Hastelloy B-3 and C-276’s corrosion rate:Fe3+ concentration>temperature>HC l concentration. Effect of TA1’s corrosion rate: temperature>HC l concentration>Fe3+ concentration.In electrochemical experiments, with the increasing of HC l concentration or temperature, the Hastelloy B-3, C-276 and TA1’s current density of passive region increases, and the passivation film stability weakened. With the oxidative ions(Fe3+ and Cu2+) added, Redox potential of solution increase s. Hastelloy B-3 directly enter the transpassivation region without passivation region. And the passivation film is dissolved. The self-corrosion potential of Hastelloy C-276 increases significantly, while the transpassivation potential is unchanged. The passivation region is shortened, and the passivation film stability is changed. The self-corrosion potential of TA1 increases, but the current density of passive region of TA1 decreases, the corrosion rate decreases, the corrosion resistance increases. It shows that Fe3+ can play a role in the corrosion inhibition of TA1, and there is no passivation phenomenon.