Abstract
This paper deals with an experimental evaluation of bending fatigue strength for austempered ductile iron (ADI) spur gears. The module is 2.5 and the number of teeth is 26 in the test gears. The material of test gears is corresponding to JIS FCAD1100-15. Two types of fine particle bombarding (FPB) are processed for some gears. The surface roughness becomes worse slightly by FPB process. The obtained strengths are 623 MPa as austempered, and 1011 to 1085 MPa with FPBs. The strength is expressed by the fillet stress level, which is calculated by FEM. The strength of same-dimension gear, which is made by an alloy steel SCr420H and carburized is 1205 MPa. The strength of ADI gear is approximately half strength of carburized steel gear. The effect of FPB process is significant in ADI gears, and the strength is improved to 62-74%.
