Cracking Analysis of Heave-duty Thermal Refined Input Gear Axles

Cracking was found in a heave-duty thermal refined input gear axle after 9 months storage period. Analysis was performed on the cracking zone by chemical compositions analysis, macroscopical and microscopical examination, fracture analysis and mechanical properties testing to find the cracking reason of the input gear axle. The results show that the input gear axle failure resulted from hydrogen induced cracking. The main reason for the cracking was high hydrogen content, serious segregation and many nonmetallic inclusions in the raw material, and insufficient forging, which made large interior stress form and hydrogen gather in the input gear axle, and hydrogen induced cracking happen finally.