Effect of impingement angle on slurry erosion behaviour and mechanisms of 1017 steel and high-chromium white cast iron

Abstract

In the present work a series of systematic erosion tests were carried out to investigate the influence of impingement angle on erosion mechanisms of 1017 steel and high-Cr white cast iron using a slurry whirling-arm test rig. Scanning electron microscopy (SEM), image analysis system, optical microscopy as well as gravimetric and microhardness measurements were utilized to identify the slurry erosion process. Test results showed that, the effect of impingement angle on erosion mechanisms of 1017 steel has three regions. In the first region ( θ ≤ 15°) shallow ploughing and particle rolling were the dominant erosion mechanisms, microcutting and deep ploughing in the second region (15° < θ < 75°), while indentations and material extrusion prevailed in the third region ( θ ≥ 75°). For high-Cr white cast iron the test results showed that, the erosion mechanisms involved both plastic deformation of the ductile matrix and brittle fracture of the carbides. At low impingement angles (up to 45°) observations of microphotographs of the impacted surfaces revealed that, plastic deformation of the ductile matrix was the dominant erosion mechanism and the carbides fracture was negligible which lead to small erosion rate. Whereas, at high impingement angles (greater than 45°) gross fracture and cracking of the carbides were the main erosion mechanisms in addition to indentation with extruded lips of the ductile matrix.