Shrinkage and looseness
This type of porosity defect, which destroys the metal continuity, causes stress intensive and crack sources, and is an unacceptable disadvantage.
When the ingot is blanked, the amount of removal is not enough, and the residual shrinkage hole and looseness are expressed. The tubular hole at the end of the forging is probably tight and loose.
The countermeasures are:
1) Strictly control the pouring temperature and rate to prevent low temperature slow injection;
2) Accept the fever riser or the adiabatic riser, improve the feeding conditions, and move the shrinkage hole up to the riser area to prevent the shrinkage hole from reaching the ingot;
3) Control the rate of ingot cutting of steel ingots during casting, and fully cut the defects of shrinkage. Reasonable forging deformation, compaction and looseness.