Development of Carburizing Steel for Innovation in
Parts Manufacturing Process
No.23 March 2018 - Special Issue on “Steel Sheet for Can-making”, “Steel Bar and Wire Rod” and “Slag Products”
Development of Carburizing Steel for Innovation in Parts Manufacturing Process
IMANAMI YutaTOMITA KunikazuNISHIMURA Kimihiro
Abstract
In order to develop a new carburizing steel that realizes an intermediate heat treatment-free process (omission of annealing before cold forging and normalizing before carburizing) in the manufacture of carburized parts, the cold forgeability of the as-rolled steel and suppression of abnormal grain growth of austenite (γ) during carburizing were studied. It was shown that optimization of the balance of Si, Mn and Cr addition, suppression of dynamic strain aging by fixing N, and an increase of the ferrite fraction by low temperature controlled rolling are effective for reduction of deformation resistance, and Nb precipitation control is necessary for suppression of abnormal grain growth of γ. The new carburizing steel, which was developed by integrating these technologies, makes it possible to eliminate both annealing before cold forging process and normalizing before carburizing, as it displays excellent cold forgeability in the as-rolled condition and suppression of abnormal grain growth of γ during carburizing. Thus, the developed steel is an important innovation in the parts manufacturing process. The name of developed steel is JECF™.
