The role of frictional power dissipation (as a function of frequency) and test temperature on contact temperature and the subsequent wear behaviour in a stainless steel contact in fretting

Abstract

a b s t r a c tTemperature is known to affect the fretting wear behaviour of metals; generally, a critical temperature is observed, above which there are substantial reductions in wear rate, with these being associated with the development of protective oxide beds in the fretting contact. This work has examined the grosssliding fretting behaviour of a stainless steel as a function of bulk temperature and fretting frequency (with changes in the fretting frequency altering the frictional power dissipated in the contact amongst other things). An analytical model has been developed which has suggested that at 200 Hz, an increase in the contact temperature of more than 70 1C can be expected, associated with the high frictional power dissipation at this frequency (compared to that dissipated at a fretting frequency of 20 Hz). With the bulk temperature at either room temperature or 275 1C, the increase in contact temperature does not result in a transition across the critical temperature (and thus fretting behaviour at these temperatures is relatively insensitive to fretting frequency). However, with a bulk temperature of 150 1C, the increase in temperature associated with the increased frictional power dissipation at the higher frequency results in the critical temperature being exceeded, and in significant differences in fretting behaviour.

The Role of Temperature and Frequency on Fretting Wear of a Like-on-Like Stainless Steel Contact

“…It is known that rates and mechanisms of damage in fretting depend upon (amongst other things) both temperature and fretting frequency, and in recent work by the current authors, it was argued that these two do not act independently of each other [2]. The temperature affects the progress of fretting via: (1) the mechanical properties of the bodies undergoing fretting; (2) the rate of oxide formation on the fretting surfaces; (3) changes to the way that oxide particles thus formed either are retained in the contact (and potentially develop into a glaze) or are expelled from the contact [3,4].…”

“…The experimental methods and materials used in this work have been described in detail in previous work [2] but will be outlined again here for completeness.…”

“…In this programme of work, both specimens were maintained at the same temperature. As a modification to the test set-up employed in previous work [2], a layer of thermal insulation was used to cover the whole test area to limit heat flow and reduce thermal gradients.…”

“…The temperature affects the progress of fretting via: (1) the mechanical properties of the bodies undergoing fretting; (2) the rate of oxide formation on the fretting surfaces; (3) changes to the way that oxide particles thus formed either are retained in the contact (and potentially develop into a glaze) or are expelled from the contact [3,4]. The fretting frequency can also affect these three influences as a result of: (1) temperature changes in the region of the contact due to the variation of the friction power dissipation; (2) changes in the time between interactions of an asperity in the contact (which will influence the oxidation of the nascent metal which takes place); (3) changes in the motion of debris particles and thus their retention in (or egress from) the contact [2,5]. Details of these three primary mechanisms of influence will now be addressed.…”

“…In this work, both environmental temperature and fretting frequency (since fretting frequency also exerts a strong influence on the contact temperature [25]) were varied to study their effects on fretting behaviour of a stainless steel. Extending our previous work [2], tests of different (and extended) durations were conducted in order that the evolution of damage can be understood.…”