Slurry erosion of tool steels by large erodent particles

Most of the erosion wear studies that have been conducted so far have been using particle sizes in the range of 20 mu m-1000 mu m. This research aims to bridge that gap by elucidating the effect of using large particles (2-4 mm) on erosion wear on a set of ten different tool steels using a slurry with 7.5 wt % of crushed silica at an impingement angle of 45 degrees. Based on the effect of hardness on erosion resistance, the materials can be separated into two groups: One group of tool steels showed a good relationship between erosion resistance and initial hardness while the other group showed much less dependence on alloy hardness. No clear trend was observed on the effect of carbide volume fraction on erosion resistance. It was found that the ratio of hardness to Charpy impact toughness (CVN), Hmax/CVN, was an important parameter affecting the erosion resistance; wear loss increased initially with increase in the Hmax/CVN ratio and reached maximum at the ratio of 122.5. Further increase in this ratio led to decreased erosion resistance. Microhardness profile measurements beneath the wear surface revealed that the strain hardening of the matrix might have contributed to dissipating damage produced by the impact of large erodent particles. Additionally, wear scar analysis showed that microcutting and microploughing were the main operating wear micromechanisms along with indentation and microcracking for some steels. Indentation was less pronounced for steels having higher hardness/impact toughness ratios.