Influence of heat treatment and densification on the load capacity of sintered gears

ABSTRACT

The powder metallurgical manufacturing of gears offers a promising opportunity in terms of reducing the noise emission and increasing the power density. Sintered gears weigh less than conventional gears and potentially have a better noise-vibration-harshness behaviour, due to the remaining porosity. However, the potential of sintered gears for highly loaded applications is not fully utilised yet. Six variants of surface densified and case-hardened sintered gears from Astaloy Mo85 are tested to analyse the impact of the densification and case hardening depths on both the tooth root and flank load bearing capacities. Experimental investigations including metallography and computer tomography are carried out to characterise the microstructure. Furthermore, a simulation model is developed to quantitatively describe the residual stress and hardness profiles after the heat treatment. The load bearing capacity was improved by increasing the densification and case hardening depths, where the effect of the case hardening was identified to be predominant.

KEYWORDS:

• Powder metallurgy
• sintered gears
• surface densification
• case hardening
• load bearing capacity
• residual stresses
• numerical modelling
• heat treatment simulation
• gears

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the Federal Ministry for Economic Affairs and Energy for providing the financial support for the project [IGF 19025N] based on a resolution of the German Parliament and the support by the Research Association for Power Transmission Engineering (FVA).