Effects of Strain Rate on Cracks Formation of Brittle Inclusions Boundary Inside Forgings
The internal brittle boundary inclusion cracks of the large forgings are the main defects affecting its fatigue life and impact properties. The strain rate and stress state in hot forging deformation are the two major factors affecting the cracking of internal boundary brittle inclusion formation of large forgings. The hot specimens were upset at different strain rates on the Gleeble-3180 thermal simulation testing machine. The formation of specimen brittle inclusion boundary crack was observed on the scanning electron microscope. The test shows that under upsetting deformation of 1220℃, when the strain rate is less than 1×10-5s-1, the brittle inclusion boundary has no crack formation; when the strain rate is more than 1×10-5s-1, the brittle inclusions boundary cracks easily.