depth of nitration layer :0.50-0.80mm
hardness of nitration :900-1000V
Fragility of nitration :less than grade 1
Roughness of the surface:Ra0.4
linearity of the screw :0.015
The surface hard chromium plating hardness after  Nitrogenation :more than 950HV
nitrogenation :more than 950HV
Chromr -plating layer thickness :0.025-0.085mm