Worn surfaces of A0 and A3 specimens under the load of 35 N are exhibited in Fig. 12. From Fig. 12a and b, it can be clearly found, worn surfaces of both A0 and A3 are full of parallel ploughings. From Fig. 12a, it can be visible that, there are obvious fracture, cracking and peeling phenomena existing on worn surface of A0 specimen. However, as shown in Fig. 12b, worn surface of A3 is relatively smooth and nearly no crack occurs on the bottoms of ploughings. Moreover, fracture of SiC abrasive may occur at the end of ploughings. According to Fig. 10, it is not difficult to explain the above phenomenon. Due to its poor toughness, M2B in Fe–3.0 wt% B cast alloy without Cr addition can easily fracture and be peeled off during the micro cutting of SiC abrasive. In reverse, with appropriate Cr addition, fracture toughness of M2B can be improved obviously. The improvement benefits the resistance against the damage from abrasive particles. Fig. 12c and d shows the color 3D laser micrographs of the worn surfaces of A0 and A3 specimens, respectively. From Fig. 12c and d, it can be clearly found that the worn surfaces are full of ploughings. Furthermore, it can be observed that roughness of the worn surface of A0 is obviously higher than that of A3, which is in accordance with the results in Fig. 12a and b. In a word, fracture toughness of M2B is an important factor to influence the morphology of the worn surface of Fe–B alloys.