| 摘要 |
PROBLEM TO BE SOLVED: To improve a tool life not only in continuous cutting but also in discontinuous cutting by allowing steel to contain Al, B and N and forming depositions of AlN on a cutting tool face at the time of cutting. SOLUTION: As for the contents of Al, B and N in the steel, preferably, by weight, 0.01 to 0.15% Al, 0.0030 to 0.020% B and 0.0050 to 0.020% N are controlled. Al is needed for the deoxidation of the steel and is also needed for forming AlN depositions on a tool face at the time of high speed cutting. B and N are bonded in the steel to form into BN, which is brought to react with Al in the steel on the tool face at the time of high speed cutting to form into AlN and is deposited on the tool face. Moreover, though it generally says that Ca-contg. steel has tool wear suppressing effect at a high speed, Ca is bad in the yield in continuous casting, and there is not composite effect by the addition of Ca, and, therefore, Ca is not substantially contained. Concretely, Ca content is preferably controlled to <=0.0010 wt.%.
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