Wear mechanism for furnace and water cooled specimens after ion-nitriding was investigated. Specimens made of A131-B Steel (ASTM Designation) were ion-nitrided at 500℃, 5 torr for 1 hr or 3 hours. Residual stress distribution was measured by Blind-Hole Drilling Method.
The results showed that the case of the ion-nitrided specimen was in a state of compression and the core was in a state of tension. The magnitude of the maximum compression stress of the case for water cooled specimens after ion-nitriding was much larger than that for furnace cooled specimens after ion-nitriding.
Microscope (both optical and scanning electron microscopes) observations showed that the principal wear proceeded by subsurface deformation, crack nucleation and crack propagation, i.e., by delamination. Wear volume of the ion-nitrided specimens was smaller than that of non-nitrided specimens. Especially, water-cooled specimens were more beneficial to wear resistance than furnace-cooled specimens as the sliding distance and wear load were increased.
