Study On Corrosion Characteristics And Mechanical Properties Of Q370 Steel Plate After Strong Corrosion

As the country gradually promotes the construction of large-span bridges,bridge steel is often used in steel-hybrid combination girder bridge structures and steel bridge structures.Bridge steel,as high-performance steel with good strength and stiffness,is widely used in the field of bridge construction.In recent years,due to frequent accidents of transporting corrosive liquid tankers at home and abroad,corrosive liquid spills and leaks on the bridge deck can lead to degradation of the mechanical properties of bridge steel,which seriously affects the safety and durability of bridge steel.This paper takes Q370 steel plate under strong acid corrosion environment as the research object,and uses a combination of experimental and numerical simulation to study the corrosion characteristics and mechanical property degradation of the specimen after strong corrosion,mainly through strong acid corrosion test and static tensile test and finite element simulation,and fatigue performance analysis based on the actual morphology of the corroded steel plate,to study the corrosion on the fatigue performance of bridge steel The effect of corrosion on the fatigue performance of bridge steel was investigated to reveal the relationship between the corrosion characteristics and mechanical degradation of bridge steel and the degree of corrosion.The main studies are as follows:(1)Using 36% concentrated hydrochloric acid as the corrosion medium,nine groups of strong acid corrosion tests with parallel time periods(0h,1h,2h,4h,8h,12 h,24h,48 h,72h)were designed,and the specimens were weighed and measured before and after corrosion section treatment,and two methods of mass loss rate and section loss rate were used to calculate the corrosion rate.Study the trend of the two corrosion dynamic curves as the corrosion time increases.(2)The surface of the specimen was scanned with the help of ST400 three-dimensional non-contact morphological scanner,and the three-dimensional surface morphology and point cloud coordinate data of the corroded steel plate were obtained,etc.The relationship between the three-dimensional roughness parameters and the maximum etch pit depth and corrosion time were fitted.The surface of the specimen was scanned by Quanta FEG 400 field emission electron scanning microscope,and the microscopic morphology and elemental energy spectrum were obtained.(3)The stress-strain curves and mechanical property parameters of the specimens after corrosion were obtained by indoor room temperature tensile tests,and the mechanical property parameters elastic modulus,yield strength,tensile strength,flexural strength ratio and elongation were fitted with the corrosion time and corrosion rate,respectively.The relationships between the control parameters S1,S2,S3 and corrosion time were fitted based on the equations of the secondary plastic flow model,and the agreement between the secondary plastic flow model and the experimental intrinsic model was compared and analyzed.(4)With the cross-sectional area loss rate as a reference,a finite element model with etch pits was established by ABAQUS software to obtain the fracture parameters and make corrections to obtain the corrected VGM and SMCS fracture model formulas,calculate the fracture displacements under the two fracture models,and compare them with the experimental values.(5)Based on the inverse reconstruction technique,the solid model obtained by inversion is imported into ABAQUS and FE-safe software to simulate and analyze the fatigue life of the specimen after corrosion,change the stress magnitude in a graded manner according to the stress level,fit the S-N curve of the solid model after corrosion,and compare it with the S-N curve of the model of the uncorroded specimen to study the change law of the effect of corrosion on the fatigue performance of bridge steel.