Experimental Research On Wear And Erosion Resistance Of High Chromium White Cast Iron

Centrifugal coal water slurry pump is taken as key equipment of pipeline hydraulic transportation, it is mainly used to transport solid-liquid mixture which has certain corrosive and contain hard coal particles. It is very easy to produce serious abrasive wear, erosion wear and cavitation erosion. Cr26high chromium white cast iron is chosen as a study object. A series of heat treatments were employed to Cr26white cast iron to obtain optimum heat treatment process, the wear resistance of which were then assessed by abrasive paper wear test and MRL screen-type ring block abrasion test. Erosion resistance of Cr26high chromium white cast iron was assessed by gas jet erosion test machinery. Metallographic inspection was conducted by light optical microscope (LOM), scanning electron microscopy (SEM), and the surface topography microscopic observation of the specimen after abrasion test was carried out using three dimensional profilometer. The wear and erosion mechanism was analyzed. The conclusions drawn from this study are as follow:optimum heat treatment process of Cr26high chromium white cast iron is quenching at1000℃(air-cooled) for2h, and follow with tempering at400℃(air-cooled), compared with the company result, the hardness after heat treatment improved2HRC. The wear resistance of high chromium white cast iron is joint decided by the hardness and the toughness of matrix, Subject to the "supporting" effect of matrix and the "protective" effect of hard carbide. In a certain range, the hardness is higher, the better of wear resistance. While the hardness is similar, the high toughness of the material has better wear performance. The mass loss is caused by the cutting of matrix microstructure and the fracture of hard carbide. Erosion resistance of high chromium cast iron is related to impact angle of particle. When impact angle is30°, the cutting force in the horizontal direction is largest, so the amount of material erosion is larger, while the impact angle is90°, some erosion particles embedded in matrix formed abrasive grains, and the subsequent impact is hindered. It is shown that the erosion of high chromium white cast iron is mainly caused by micro-cutting and carbide fracture. Laser hardening experiments on Cr26high chromium white cast iron are carried out to explore the effect of laser parameters (power) on the hardened layer thickness and microhardness. It provided important theoretical and experimental basis for further research on the high chromium white cast iron.