Fine friction cutting of some nickel–chromium alloys

Abstract

Some nickel–chromium alloys have been slit by pressing them against toothless mild steel discs spinning with rim speeds between 20 and lOOms⁻¹. The discs were from 0·13 to 0·76 mm thick and were water cooled. Material was removed from the alloys by adhesive wear. Two states of slitting were observed corresponding to mild and severe wear. The severe state gave slitting times comparable with chip-forming slitting processes, together with acceptably low disc-wear rates. Mild or severe slitting occurred depending on alloy composition, coolant composition, disc speed and load, and test geometry. Alloys with low Ti and Al contents tended to mild behaviour, those with more than 3%Al tended to severe behaviour, and those with a low Al content but more than 1%Ti could be switched from mild to severe behaviour by adding basic sodium salts to the water coolant. Chemical analyses suggest that loss of chromium from the slit surfaces results in mild slitting and suppression of the loss causes severe slitting.