Cracking failure analysis of steel piston forging die

The steel piston forging die used in an enterprise prematurely lost its function due to the corner crack at the bottom of die cavity. In order to determine the cause of the cracking, the structure of the crack was observed with optical light microscope. The fracture morphology was examined by scanning electron microscopy (SEM) method. Micro-hardness was also tested to assess the mechanical property of the die material. Furthermore, stress distribution in the die during forging was evaluated by finite element analysis (FEA) method. The investigation shows the uneven distribution of carbides in the die material is the main reason for premature failure of die, and the material oxidation at the high temperature and the coarse grain also reduce the ability of material resistance to fracture failure. The stress concentration decreases further the material endure to the fatigue load resulting from the strong impact and thermal loading during forging.

Automated summary

This study uses optical observation, fracture morphology analysis, microhardness testing, and finite element analysis to determine that the uneven distribution of carbides in the die material, high temperature oxidation and coarse grain, and stress concentration caused by fatigue loading are the reasons for the premature failure of the steel piston forging die.