The Influence of Microcracks Generated During Forging on Crack Propagation in Steel Forgings

Abstract

This article investigates the formation of solidification cracks in steel forgings used for bearing rings in gear reducers of robotic arms. The forging and heat treatment processes, conducted under consistent technological conditions, revealed the occurrence of high-temperature annealing cracks caused by plasticity depletion during stress relaxation. Additionally, solidification cracks were analyzed, with chemical compositions and hardness measurements indicating susceptibility due to elevated carbon and chromium content, as well as a high cracking parameter. Die tool wear and damage during forging were identified as key contributors to crack formation, transferring surface defects, inclusions, and creating cracks that propagate during subsequent processing. The findings underscore the influence of the tooling conditions, material properties, and process parameters on the quality and reliability of steel forgings.