Influence of Grain Refinement by ECAP on Mechanical and Erosion Corrosion Properties of AISI 4130 Steel: Experimental and Prediction Approach

Abstract

Sever plastic deformation (SPD) is widely employed to make ultrafine-grained structure (UFGS) materials that satisfy desired properties such as high strength, good tribological properties, and lightweight. Equal channel angular pressing (ECAP) is one of the most important SPD techniques. The current work studies the effect of ECAP passes on mechanical properties, microstructure, and the erosion–corrosion (E–C) resistance of AISI 4130 steel. ECAP at high temperature according to Bc route (billet rotation 90 deg counterclockwise after every pass) was applied and UFGS AISI 4130 specimens with an average grain size of 500 nm were obtained after four ECAP passes. Consequently, the effects of ECAP on the tensile, hardness, and impact properties were investigated. The E–C resistance of unECAPed and ECAPed specimens was evaluated by using seawater slurry with specified sand concentrations. Various microscopes were employed to investigate the microstructure and surface changes due to ECAP and E–C. The results showed that the AISI 4130 steel processed by ECAP has enhanced mechanical and E–C properties. The main mechanisms of E–C are plastic deformation, craters, and small pits. A predication model based on an artificial neural network (ANN) was developed to predict the E–C behavior of both unECAPed and ECAPed materials. The model is able to estimate the weight loss without the need to perform extra experiments. A good agreement between the predicted values and the experimental results was achieved.