Bottom Poured vs Top Poured Steel Ingots
How bottom pouring and top pouring differ for steel ingots, and why forging quality ingots are usually bottom poured.
Top pouring
In top pouring, steel is poured from the ladle straight into the open mould. It is simple, but the stream splashes, picks up oxide and can leave surface defects.
Bottom pouring
In bottom pouring, steel flows from the ladle through a runner system into the base of the mould, so the mould fills quietly from below. The stream is protected from air, which gives a cleaner surface and fewer inclusions.
Which one for forging
Forging quality ingots, especially alloy and heavy ingots, are usually bottom poured. The cleaner surface cuts grinding and the lower inclusion level improves fatigue life. Kesari Alloys bottom pours its forging ingots after vacuum degassing.
Trade-offs
Bottom pouring needs more setup (runners and trumpets) and a little more steel lost in the runner system, but the cleanliness and yield of the ingot body repay it.
Related guides
Vacuum Degassed Forging Ingots: Why Vacuum Matters
How vacuum degassing removes hydrogen, oxygen and nitrogen from steel and why it matters for heavy forgings.
Hot Top Forging Ingots: Over Imposed vs Semi Inserted
What a hot top does, how over imposed and semi inserted hot tops differ, and how it affects ingot yield and soundness.
Common Forging Ingot Defects and How They Are Prevented
Pipe, segregation, cracks, inclusions and flakes in forging ingots: what causes them and how to reduce them.