Influence of Heat and Cryogenic Treatments on the Abrasive Wear Behavior of H13 Tool Steel

This study analyzes the influence of cryogenic treatments, before the pre-tempering treatment on the microstructure, and the mechanical properties of the H13 tool steel. The H13 tool steel was subjected to the shallow cryogenic treatment SCT (at –80 °C for 24 h) and deep cryogenic treatment DCT (at –185 °C for 24 h) between hardening and pre-tempering processes (at 650 °C for 15 min). Alternatively, the tool steel was exposed only to the hardening and pre-tempering processes. The characterization of the microstructures and phase transformations of the specimens was established via scanning electron microscopy and X-ray diffraction, respectively. The mechanical behavior of the treated H13 tool steel was estimated using the Rockwell hardness and abrasive wear tests. Upon completion of the quenching treatment, the H13 tool steel presented the formation of fine, thin crystals of lath-shaped martensite, while the subsequent pre-tempering treatment formed a microstructure with wider martensite laths than the as-quenched state. The sub-zero treatments on the H13 tool steel promoted several phenomena, such as the martensitic transformation, the refinement of martensite laths, and the formation of large and fine carbides dispersed in the whole microstructure. The specimens exposed to SCT and DCT achieved an improvement in hardness values due to structural changes, which also contributed to a better wear resistance (17 and 25%, subsequently) in comparison with the tool steel exposed exclusively to the pre-tempering treatment. Meanwhile, the failure mechanisms on worn surfaces of the treated H13 tool steel were micro-cutting and pitting, which were developed during the interactions among the specimen surfaces-abrasive particles-rubber wheel.