| The machinability of Ca-added microalloyed steel was characterized in terms of tool life, chip-breaking, and cutting force compared with that of Ca-free steel Microscopic examination revealed that inclusions have a globular shape of calcium aluminate surrounded by (Mn,Ca)S. The composition of calcium aluminate was 12CaO·7Al₂O₃+ CaO·Al₂O₃ through EPMA analysis, which had the lower melting point than alumina. The tool life for Ca-added steel was about twice as longer than that for Ca-free steel while chip-breaking and cutting force had no difference between. Based upon the above results, it is suggested that the enhancement of tool life is caused by lubrication of the inclusions, calcium aluminate, which were softened and sticked to tool surface during machining. |
|
