Experimental study of erosion behavior under fluctuating tensile loads

When studying the erosion behavior of fracturing pipelines, it is inevitable to consider the exacerbating effect of fluctuating internal pressure on pipeline erosion damage. Therefore, an erosion experimental apparatus capable of applying fluctuating tensile loads to specimens was developed to investigate the erosion rate of 35CrMo steel at different average tensile stresses (0–500 MPa), impact angles (15–90°), flow velocity (7.5–20 m/s), and experimental times (10–60 min), and to analyze the erosion damage mechanism under fluctuating loads by observing the microstructure within the erosion scars using scanning electron microscope. The results indicated that erosion rate increased up to 36.84% compared to that without loading under the same erosion condition. Erosion rate increased up to 822.00% when velocity increased from minimum to maximum. Under fluctuating loads, the deepest part of the erosion scar cracked first and the specimen eventually fractured completely along with its entire width, demonstrating that the newly established experimental conditions can well reproduce the sudden bursting phenomenon common to high-pressure pipelines that erode under harsh conditions. The fracture of the specimen shows laminar structure, which is a typical damage feature resulting from the combined effect of a great number of tensile stress cycles and erosion wear.