| Impurity | H | Increase | The interaction of the increase of the local plastic deformation near the grain |
| element | | | boundary and the decrease of the bonding force between the precipitate and |
| | | the grain boundary |
| S, P | Increase | Segregation at the grain boundary reduces the bonding strength of grain |
| | | boundary and causes grain boundary embrittlement |
| Addition | B | Decrease | Increase the bonding force of metal atoms on grain boundary, and increase the |
| element | | | fracture resistance of grain boundary |
| Nb | Decrease | Formation of NbC intergranular precipitate provides grain boundary locking, |
| | | changes grain boundary morphology, and hinders grain boundary sliding |
| | | and formation of porosity |
| Mn | Decrease | Strong affinity for S |
| Ti | Decrease | Formation of Ti rich nitrides and carbides makes the equilibrium phase changes |
| | | to (MTi)(CN) during the solidification temperature range, and provides grain |
| | | boundary locking effect |