THE INFLUENCE OF TEMPERATURE ON FAILURE DEVELOPMENT IN STEELS UNDER TRANSITION TO SEIZURE

Seizure phenomena in pin-on-disk tests have been studied for ''soft'' and ''hard'' steel specimens. Differences in competing and dominant we ar mechanisms under steady stare friction have been presented for ''so ft'' and ''hard'' specimens in the region of transition to seizure or. galling. Severe wear was observed for ''soft'' specimens under all le nds tested, while adhesion and splitting off of wear particle conglome rates (microseizure) were identified for ''hard'' specimens. The conta ct temperature, calculated in accordance with the temperature model of plastically deformed contact spots (Kuhlmann-Wilsdorf), has appeared to be low for ''soft'' specimens and not sufficient for adhesion inter action The effect of oxide films on the friction of ''hard'' specimens has been estimated in accordance with the temperature model for a coa ted semi-infinite body (Tian and Kennedy). The insulated oxide films o n the surface of ''hard'' specimens create the ''skin effect'' and lea d, therefore, to raising the temperature up to the temperature of adhe sion interaction Temperature instability of hard surfaces has been dem onstrated to result from the ''skin effect'' and from a disturbance in equilibrium of formation and failure of oxide films. It has been show n that for ''soft'' specimens the prime cause of transition to seizure was the mechanical interlocking between the wear particles and the so ft disk surface combined with mechanical instability, while for ''hard '' specimens the cause was temperature instability. A more realistic t emperature model of the contact has been considered, which takes into account some competing wear mechanisms (oxidational wear, ploughing, d elamination) and the effect of wear particles.