Fracture failure analysis of electric tool gear

摘要

The failure analysis for a gear used in an electric tool is studied in this paper. Several tests were accomplished,including the hardness measured by a semi-automatic HAVSE Vickers durometer,and the metallurgical structure and fracture appearance of the gear observed with an optical microscope and a scanning electron microscope. The results show that the gear failure results from the bending fatigue crack propagation and the fast ductile fracture. For improving the electric tool gear's design,better materials,such as 40Cr or 40CrMn,should be used for the electric tool gears and appropriate heat treatments should be carried out for improving the properties of strength and fatigue.