Wear behaviour of austempered, ductile iron microalloyed with boron under different contact load by dry sliding wear conditions

Abstract

In the preformed work were studied the characteristics of Ni, Mo and Cu – free austempered ductile iron microalloyed by Boron under different contact load. For microalloying liquid cast iron with boron, the ferroboron by synthesized SHS - innovation technology was used. The upper and lower bainitic austempered ductile irons were studied with different content of metastable retained austenite. The experimental samples were tested with a fixed linear sliding speed of 2 m / s at a different contact load values, which were changed in the range of 25, 50 and 100 Newtons. It was defined that the value of the contact load has a significant effect on the tribotechnical characteristics of bainitic cast irons in conditions of dry sliding friction. Particularry, they determine the structural changes character and the degree of surface layers degradation of friction. High strength cast irons with the lower bainite structure are more resistant to adhesive wear. According to the obtained data, the presence of up to 80% metastable retained austenite in the metal matrix structure of the of experimental cast irons makes it possible to stabilize the friction coefficient under the investigated contact loads. Thus, to ensure maximum wear resistance, the isothermal quenching of high-strength cast irons must be carried out in the temperature range 220-280 0C with a minimum treatment time.