Abstract: Taking ZG25CrNiMo low alloy wear-resisting steel as the research object, two groups of the tested steels without Ce and with 0.021%Ce were prepared. Firstly, the influence of quenching temperature on hardness was studied to determine the best heat treatment process. Then the effect of rare earth Ce on inclusions, microstructure, impact property and wear resistance of the tested steel was studied and the mechanism was analyzed. The results show that the best heat treatment scheme of the ZG25CrNiMo low alloy wear-resistant steel is 980 ℃×1 h normalizing+675 ℃×1 h tempering+970 ℃×1 h water quenching+205 ℃×1 h tempering. Compared with the steel without Ce, the inclusions in the steel adding 0.021%Ce are modified from large and irregular Al₂O₃ and MnS inclusions to small and spherical Ce₂O₂S rare earth inclusions. After heat treatment, the hardness of the tested steel increases from 512 HV0.1 to 538 HV0.1. The group of martensitic lath per unit area increases, and the width of the lath decreases from 0.50 μm to 0.36 μm. The impact absorbed energy of the tested steel increases from 20.7 J to 32.0 J at －40 ℃ and from 31.3 J to 44.7 J at 25 ℃, and the impact property increases significantly. After 120 min impact wear, the wear mass loss decreases from 660 mg to 550 mg. After wear, the ploughing depth on the surface becomes shallow, the proportion of peeling pits is significantly reduced, and the wear resistance is increased by 20%. The improvement of inclusions and refinement of microstructure in the low alloy wear-resistant steel ZG25CrNiMo by rare earth Ce is the main reason for the improvement of impact property and wear resistance of the tested steel.

Key words: rare earth Ce, low alloy wear-resistant steel, heat treatment, inclusion, martensitic lath, impact property, wear resistance