Experimental Study On Erosion Corrosion Of 304 Stainless Steel In Two-Phase Flow

Erosion corrosion is widely found in oil and gas production lines,mines,hydroelectric power stations,nuclear power plants,marine engineering and many other fields,and is a common way of material damage.304 stainless steel and 316 stainless steel play an irreplaceable role in plate heat exchangers,household appliances,auto parts,medical building materials,food industry,coastal facilities and other industries.Liquid-solid two-phase flow is a form of erosion corrosion,which is the result of synergy between erosion and corrosion.Therefore,understanding the erosion corrosion behavior of stainless steel under various factors,constructive suggestions and protective measures are particularly important.In this thesis,the effects of different experimental factors on the wear resistance of 304 stainless steel were discussed from the particle size effect of erosion wear,the promotion of different static corrosion conditions and the synergistic interaction of erosion corrosion.The results of the particle size effect of erosion show that the mass loss per unit time and the particle size are in a power function under different impact angles of attack.Under different impact angles,the power index n is slightly different.At 45° impact angle,n is equal to 1.31 when the particle size is less than 256?m;n is equal to 0.42 when the particle size is more than 256?m.At 90° impact angle,n is equal to 1.54 when the particle size is less than 181?m;n is equal to 0.51 when the particle diameter is more than 181?m.The results of erosion experiments under different static corrosion conditions show that the corrosion resistance of the material decreases with the increase of solution temperature and chloride ion concentration.The polarization curve of the sample in the solution temperature range of 20? to 80? and The results of electrochemical impedance spectroscopy show that the corrosion resistance of the material is the worst after immersion in 3.5wt% and 80? chloride ion solution.The experimental results of the synergistic interaction of erosion and corrosion show that 3.5wt% of chloride ion greatly reduces the erosion corrosion resistance of the material.Under the 45° impact angle,chloride ion promotes the erosion corrosion most,followed by 90° and 60° impact angle.Electrochemical tests show that the material passivation film becomes incomplete with increasing erosion time due to the erosion of three different impact angles.It is the main reason for the corrosion resistance of stainless steel materials.At the same time,laser scanning micrographs and scanning electron micrographs also further reflected that the surface roughness of the sample was the largest under the angle of 45°,and the damage was the most serious.