Cause Analysis on Lower Impacting Energy of Crank Throw Forging for Large Ship

The impacting energy of left side area of a crank throw forging for large ship after forging heat treatment was lower than that of the right area, and it didn’t met the technical requirement. By means of chemical compositions analysis, fracture test, metallographic examination and energy spectrum analysis, The reasons of the low impact energy was analyzed. The results show that because the normalizing temperature was higher and non-uniform, the grain of left side area of the crank throw grew up, and this was the main reason for the lower impacting energy. At the same time, there were a lot of inclusions in material of the crank throw, which also could reduce the impacting properties of the crank throw.