Fig. 4

Tool penetration and wear flat in granite. Tool penetration in Grimsel granite as a function of scratch distance is shown by the scatter plot and the left y-axis for untreated (violet squares) and after-treatment conditions (green circles). The symbol sizes represent the wear flat at the tool tip (see the legend in the figure). An enlargement of the figure for the 0–20 mm scratch distance range is shown in the inset figure. Here, the bar plot shows the wear flat increase per unit of scratch distance, i.e., the wear slope, where the values are given by the right y-axis. Contiguous bar pairs (violet for untreated and green for after-treatment conditions) are shown for the scratch distance ranges 0–4 mm, 4–8 mm and 8–20 mm. The overlapping data points at a scratch distance of 90 mm are shifted along the x-direction to visualize the wear flat (size of symbols)