Applied load F N
 Sliding velocity V m/s
 Semi contact radius r 10-3 m
 Brinell Hardness HB GPa
 Heat conduction coefficient K1 W/mK
 Heat conduction coefficient K2 W/mK
 Diffusivity k2 10-6 m2
 Coefficient of friction
 Real contact area / nominal contact area Ar /An
 Contact radius of junctions rj=0.1e6/HB 10-6 m
 Bulk temperature dTbulk C
 Flash temperature dT'flash C
 Temperature increase dT C
1Ashby, M.F., Abulawi, J., Kong, H.S., 1991, "Temperature maps for Frictional Heating in Dry sliding", Tribology Transactions, Vol.34, Number 4, October 1991, pp577-587.

With increasing contact pressure, Ar grows until it equals An, and the distinction between dTbulk and dTflash disappears. To achieve this dT=dTflits+(1-Ar/An)dTbulk, where Ar is the real contact area under tractive load (Johnson, 1968).