Unveiling the Role of Carbide in the Wear Behavior of M42 High‐Speed Steel Containing Rare Earth: Insights from Wear and Damage Mechanism Maps

In this paper, the wear behavior of M42 high speed steel (HSS) cutting tools containing rare earth elements has been investigated to reveal the role of carbides with diverse sizes in the wear of M42 HSS. A wear map and damage mechanism map for M42 HSS containing rare earth have been established. Based on the magnitude of wear rates, the wear map can be divided into three regions: mild wear, medium wear, and severe wear. As contact stress and sliding velocity increase, the damage mechanism evolves through three stages: initial slight scratching with fewer microvoids from the detachment of small‐sized carbides, followed by increased scratching with more microvoids, and culminating in severe oxidation characterized by extensive microvoids due to the fracture and detachment of larger carbides. Carbide spalling in various sizes emerges as a key factor contributing to microstructural damage and the deterioration of wear performance in M42 HSS. A quantitative correlation between carbide spalling and wear rate has been established, identifying critical thresholds of carbide spalling proportions that indicate the transition from mild to severe wear.