Adjustment of Inoculant Addition for Variations in Casting Wall Thickness

Core Principle: Prevent chill in thin sections; prevent inoculation fading and shrinkage porosity in thick sections.

Thin-wall areas (rapid cooling): Slightly increase the inoculant addition. Use a potent inoculant (e.g., containing Ba, Sr) and employ late inoculation (flow or in-mold inoculation) to ensure sufficient graphite nuclei form before rapid solidification, thus avoiding hard, brittle chill/white iron.

Thick-wall areas (slow cooling): Strictly control the inoculant addition to avoid excess, which can degrade graphite morphology. Use a long-lasting/fading-resistant inoculant, often combined with microalloying (e.g., with Sn). The process should combine ladle inoculation with late inoculation to counteract inoculation fading, preventing coarse graphite and shrinkage porosity.

Key Points:

1.The specific addition amount must be determined by process testing to balance the needs of the thinnest and thickest sections.

2.It must work in synergy with proper base iron composition, effective use of chills, and rational gating and risering design to form a complete systemic solution.