The abrasive microwear testing has been the subject of a significant amount of research in recent years, when its potential to evaluate the behaviour of thin coating became relevant. The aim of this work is to build a apparatus for abrasive microwear testing by rotating sphere. The abrasive contact is performed by a AISI 52100 steel ball which rotates, with great accuracy with the help of an electric motor, in relation to a flat sample that will remain stationary. The normal load is applied by weight adjustments in the support of the test specimen, which can be varied for each performed test. This device was used to determine the abrasive wear resistance and effectiveness of surface treatments used in parts that undergo this kind of requirement in service, and also for studying new products developed for increasing the wear resistance of surfaces. The microwear resistance of the quenched and tempered AISI 420 steel was evaluated. It was observed that increasing the hardness of the treated material produced an increased wear resistance when compared with untreated material