Influence of Material Surface Hardness and Particle Size on the Erosion of DC 11 Tool Steel
摘要
The effect of surface hardness and particle size of erodent on the erosion behavior of DC 11 tool steel was examined by sand blasting. The hardness of the steel specimens was changed by case hardening of gas nitriding and vacuum heat treating. These samples were tested in an air jet impingement tester with a range of impact angles (15-90°) and a particle velocity of 83.2m/s. Al2O3 sand particles having mean particle sizes of 115, 177 and 220μm. The results indicate that cutting is the dominated mode for material removal at oblique impact angle. At the higher impact angle, the mode is based on extrusion and cracking. At the medium impact angle, the wear is dominated by transition of mode mixed with cutting and extrusions. However, cracking is one of the major wear modes for all impact angles. The depth of cutting grooves or indentation craters of the treated samples is lower than that of normal samples. The maximum erosion rate in all cases shifts from oblique impact angle to medium impact angle with increasing hardness. They are at 15°, 30° and 45° for normal, nitrided and vacuum heat treated samples, respectively. The erosion rates decrease with increasing hardness for all impact angles. The erosion rate for impinging with particle size of 177μm is larger than finer and coarser sized particles.