Bending Durability and Impact Strength of Gear Tooth of 1.5Cr-0.2Mo Sintered Alloy Steel Gears for Automotive Transmission

Tooth Root Bending Stress Analysis of Pre-alloyed Sintered Steel Gears with Different Densities using FEM Model Considering Voids

“…In addition, surface rolling technology gives the very cost effective high precision processing of P/M gears with full surface density to improve the load bearing capacity. It has already been demonstrated that case-carburized P/M gears with a density above 7.5 Mg/m 3 made of 1.5Cr-0.2Mo pre-alloy sintered steel can achieve bending strength of 1.0 GPa 1,2) , which match with those of case-carburized gears made of the typical Cr-Mo wrought steel most commonly used for transmission gears. However, some serious problems occur as the density of the preform gear increases: the short die life and the damage of gear preforms in the compaction process, the heterogeneous void distribution in the gear teeth, the crack initiation at the tooth tip of surface-rolled gears, and so on.…”

“…In the present study, single tooth bending fatigue (STBF) tests were first performed using the case-carburized Cr-Mo pre-alloy sintered steel gears with different densities, and each S-N curves was obtained. Examining these data, we investigated the effects of lower, compared with the case of GH2 and GH2R used in the previous study 1,2) . Gear surface rolling was conducted using a CNC form-rolling machine of two roller-dies transverse-type, as shown in Fig.…”

Load bearing capacity of sintered steel gears made of completely prealloy powder for automotive power transmission

“…It has already been demonstrated that surface-rolled case-carburized gears with a density of greater than 7.5 Mg/m 3 made from this powder metallurgy (P/M) material can achieve bending and surface fatigue strengths of 1.0 GPa and 2.0 GPa, respectively [1][2]. However, because chromium can easily be oxidized during sintering or case-carburising in RX gas, there is a greater risk of reduction in the fatigue strength of the Cr-Mo P/M gears.…”