Abstract:The work aims to study the effects of blast gun moving direction and sandblasting angle on surface roughness and the fraction of embedded grit. The samples were processed by automatic sandblasting equipment and then characterized by scanning electron microscope (SEM), laser microscope and surface toughness tester to quantify the surface roughness and the fraction of embedded grit retained in the steel matrix. Crack propagation theory and micro-cutting theory were used to analyze the processing factors including blast gun's moving direction and sandblasting angle in affecting surface roughness and the fraction of embedded grit. Under the conditions of standoff distance of 200 mm, sandblasting pressure of 0.3 MPa, blast media feed rate of 3 kg/min and displacement speed of blast gun of 0.8m/s, the surface roughness value and the fraction of embedded grit were the smallest when the sandblasting angle was 15°. At this time, the fraction embedded grit and surface roughness were determined to be 11.28% and 8 μm respectively for the vertical direction, 15.68 % and 5.7 μm for the horizontal direction. As the sandblasting angle increases, the surface roughness reaches the maximum at 75°, with value being 11.12 μm and 10.13 μm for the vertical and horizontal directions respectively. While the faction of embedded grit reaches the maximum at 90°, with the vertical one being 25.56% and horizontal one being 25.33%. To sum up, with increasing the sandblasting angle, the surface roughness increases first and reaches the maximum at 75°, then followed by a slight decrease, while the area fraction of embedded grit increases monotonously and eventually reaches the maximum at 90°. Compared to the horizontal direction, the vertical direction always exhibits a larger surface roughness but a lower fraction of embedded grits for a given blasting angle.