In order to study the wear mechanism and the relationship between magnetic field strength and wear rate during sable dry friction between 45 steel and 45 steel under the various magnetic field strength,the dry friction tests with 45 steel as pin and disk were conducted under the various magnetic field strength.The wear properties and both the appearance and chemical composition of the worn surface were analyzed.The results reveal that the wear rate of pin sample undergoes three successive variation stages of rapid reduction,slow reduction and slight stabilization with the increase of magnetic field strength.The critical value of magnetic field strength that the pin sample changes from severe wear to slight wear is approximately 17.4×103 A/m.In the absence of magnetic field,there was a large amount of plows on the worn surface of the pin sample,and the abrasive wear is dominating.With the increase of magnetic field strength,the worn surface of pin sample is oxidized and Fe2O3 is formed on the surface,the pits come into being during friction owing to the peeling off of the oxide,and the wear type between 45 steel and 45 steel is mainly oxidative wear.The worn surface of the pin sample becomes more smooth with the increase of magnetic field strength.It can be concluded that the transformation from the abrasive wear to the oxidative wear occurs under a certain magnetic field strength and the oxidation wear mode corresponds to the mild wear between selfmatching pairs of 45 steel.