Fe < Sub > 3 < / Sub > Al On H < Sub > 2 < / Sub > S - Co < Sub > 2 < / Sub > - Cl < Sup > - < / Sup > Corrosion Behavior Modification And Heat Treatment Of The System

Specific to the problem of the high cost of the Nickel chrome materials using in the acid oil fields, the lower cost Fe3Al alloy with excellent corrosion resistance property was selected for this research. Weightlessness experiment,SECM,XRD was used to study the corrosion behavior of Fe3Al alloy under high temperature and high pressure while in H2S-CO2-Cl coexistence corrosive medium.The immersion test, polarization curve, electrochemi-cal impedance spectroscopy and Electrochemical Noise were used to analyze the corrosion behavior of Fe3Al alloy under normal temperature and pressure.Study the corrosion behavior of the phase structure of Fe3Al alloy after the B2and DO3technology for Heating Processing.The main conclusion as follow.(1) With the test pressure4.0Mpa (PH2s=1.5Mpa,Pco2=2.5Mpa),the temperature60℃and experimental period72h, the corrosion rate of Fe3Al was0.2106mm/a, the corrosion morphology was pitting corrosion and crack, and the bonding force of the corrosion product was weak and easy to fall off. The corrosion flims was FeS.(2) the polarization curve results showed that the corrosion rate of Fe3Al was lengthen with the soak time, and the corrosion rate was decreased gradually while stayed in the scope of order of magnitude of10-6A.cm-2.Then the material appeared pitting corrosion and passivation. The electrochemical impedance spectroscopy results showed that the corrosion of Fe3Al was mainly be pitting corrosion. The resistance of passive film of5.109×104O.cm2is much higher than the resistance of activate corrosive pores of103O.cm2,with the lengthening of soak time,the thickness of corrosion products increased,along with the activate resistance of39O·cm2,intergranular corrosion and denudation began to emerge.The rate of corrosion decreased at first,and then stay steady.The corrosion products presented contact group,loose and porous. The corrosion product were mainly FeS、FeS2、FeCO3、A1(OH)3、 Al2O3、Cr2O3and so on(3)The research found that the metallurgical structure was DO3and a(Fe) dual phase without heat treatment, the metallurgical structure of DO3heat treatment was quite uniform and that of B2heat treatment presented B2and a(Fe) dual phase, the composition of the grain boundary and grains was the same, XRD also verified the corresponding structure. Corrosion immersion test and polarization indicated the abilities of corrosion resistance was in the sequence below, DO3heat treatment> B2heat treatment> no heat treatment. What was more, the corrosion rate reduced first, in the end it kept stable; the type of corrosion changed from pitting corrosion to granular corrosion and then to denudation. Intergranular corrosion experiments showed that under different heat treatment processes, Fe3Al had tendency of intergranular corrosion.