Cast steel joints will inevitably produce some defects in the production process, such as hot crack, shrinkage cavity, delamination, slag inclusion, etc. the typical defect types and causes are described in detail in the table. Shrinkage cavity and porosity are the most common casting defects in cast steel joints.
| Defects | Features | Cause |
| Stomata | Smooth inner wall | Invasion pore, precipitation pore and reaction pore |
| Inclusion | Metallic or non-metallic inclusion | Endogenous or exogenous, with complex reasons |
| Thermal cracking | Zigzag cracks with or without penetration on castings | The thickness of the casting joint is too thin and the thickness of the riser is too small, which hinders the casting from casting shrinkage |
| Cold crack | Straight strip crack on Casting | The wall thickness is very different, and the temperature difference of each part of the casting is too large |
| Shrinkage cavity | Dispersed or concentrated macropores with dendrites and inclusions | It is usually caused by poor feeding at the last solidification of the casting. The long solidification period is usually related to the improper setting of the casting system |
| Shrinkage porosity | There are intergranular pores with a certain size, which often appear below the shrinkage cavity | Small shrinkage is unavoidable |
| layered | Long banded distribution | Complex causes |
| The core support is not fused | / | The core support or internal cooling iron remaining in the casting is not completely melted |
Shrinkage cavity is the hole produced by the shrinkage of cast steel joint in the condensation process and can not be supplemented by liquid metal. It has irregular shape and rough hole wall, which is generally dispersed in the hot joint of cast steel joint. Shrinkage porosity is the dispersion and small holes formed in the last solidification area of cast steel joints without the feeding of liquid metal. It often appears in the thicker section, the junction of thick and thin sections or hot joints of cast steel joints.
The distribution area of shrinkage porosity is much larger than that of shrinkage cavity, showing a state of dispersion distribution. It is generally hidden in the interior of cast steel joints, sometimes invisible to the naked eye, and small shrinkage porosity can not be avoided.