Impact Characteristics of Steel Protected from Tufftriding by Inorganic Coating

Abstract

The tufftride process is widely applied to increase the fatigue-resistance and the wearresistance of machine parts. However, their toughness is conversely reduced by the process. Therefore, the tufftrided steel is often fractured when subjected to impact load. The purpose of this paper was to make an experimental investigation with relation to the effectiveness of inorganic coating to restrain the embrittelement. The relation between the charpy impact value and the tufftriding time of the anti-tufftrided steel was examined, and the impact fracture surface was observed through SEM.
The main results obtained are as follows;
(1) The charpy impact value of the anti-tufftrided steel was reduced in accordance with tufftriding time. But its degree was remarkably small when compared with the tufftrided steel.
(2) The impact fracture surface of the anti-tufftrided steel showed the ductile fracture surface and was not seriously changed by tufftriding time.
(3) The inorganic coating can be applied most effectively to prevent the embittlment or decrease in impact value, as well as to partially prevent the tufftride process.