On the Morphology of Non-metallic Inclusions and the Machinability of Calcium Deoxidized Steel

Wear Reduction of Carbide Tools Observed in Cutting Ca-added Steels for Machine Structural Use

“…5) Many reports have stated that the rake face wear at high cutting speeds is reduced by an adhesion of oxide inclusion containing calcium to the carbide tool surface, which could work as the so-called "belag", since this oxide layer covers the tool surface and protects the tool from the diffusion wear. [1][2][3][6][7][8][9][10][11][12][13][14][15] It has been also reported that the oxide inclusion containing calcium is softer than a typical oxide like Al 2 O 3 , and that (Mn, Ca)S, which crystallized around the oxide containing calcium, reduces the abrasive effects of this composite oxide. 11,12) Furthermore, in case of machining a Ca-added steel containing higher amount of sulfur with a relatively high cutting speed, an inclusion layer, which is mainly composed of manganese sulfide, forms on the tool surface, avoiding the direct contact between the tool surface and the chip, and it works to prevent the diffusion wear.…”

“…[2][3][4] It has been widely known that inclusions in steels strongly influence the machinability. A large number of studies [1][2][3][6][7][8][9][10][11][12][13][14][15][16][17][18][19] on the mechanism of wear reduction effects, particularly in Ca-added steels, have been carried out since it was recognized at the early 1960s in Germany. 5) Many reports have stated that the rake face wear at high cutting speeds is reduced by an adhesion of oxide inclusion containing calcium to the carbide tool surface, which could work as the so-called "belag", since this oxide layer covers the tool surface and protects the tool from the diffusion wear.…”