Relationship between Surface Durability and Hardness of Sintered Powder Material (In Case of Induction-Hardened Sintered Powder Metal Gears and Rollers)

摘要

In order to evaluate the surface durability and spalling failure depth of induction-hardened sintered powder metal gears and rollers, the relationship between the surface durability and the hardness was investigated. The failure mode of the gears and rollers was spalling due to subsurface cracks. The spalling failure depth agreed almost with the peak depth of the amplitude A(τ_yz/Hυ) of the ratio of the orthogonal shear stress to Vickers hardness. The surface durability was evaluated using the amplitude A(τ_yz) of the shear stress and the hardness Hυ at the peak amplitude of A(τ_yz/Hυ). In case of the sintered specimens with a same pore distribution, the relationship between A(τ_yz) and Hυ was represented by one line. In a case of the sintered specimens with differenet pore distribution, it was difficult to evaluate the surface durability using the relationship between A(τ_yz) and Hυ. It could be understood that the pore distribution played an important role when the sintered material was designed in terms of the surface durability.