In order to evaluate the feasibility of Ca-deoxidized steels, machinability tests on variously deoxidized 0.45%C steels are done with carbide tools. The effects of deoxidation on the machinability based on tool life are investigated, and the relationship between oxygen-, aluminum-, calcium-contents in steels and their tool life characteristics is determined.
Generally, the higher oxygen content in steel is favorable for the formation of oxide layer on the tool face during cutting various steels. In cutting the steels deoxidized appropriately with Ca, however, the tool wear is found to be considerably suppressed even if their oxygen contents are fairly low. In these cases, very thin oxide layers are observed on tool faces. It seems that the formation of thick oxide layer on tool face is only sufficient condition for good machinability but is not necessary one. Negative correlation is observed between Al content and machinability of Ca-deoxidized steels.
It is confirmed that the Ca-deoxidation is applicable to Cr-Mo steels and resulphurized steels for good machinability, too.
The results of identifying analysis of oxide layers on tool faces are discussed.
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