Scale
Scale is unavoidable in hot forging but very much controllable. Long soak times in a fuel-fired furnace produce far more of it than short induction heating cycles.
Scale is the layer of iron oxide that forms on steel surfaces at forging temperature as the hot metal reacts with oxygen. It costs material, damages dies, and if pressed into the surface, leaves permanent pits.
- Definition
- Iron oxide layer on hot steel
- Material loss
- 1 – 3% of billet weight
- Effects
- Die wear, surface pits
- Control
- Short induction heating, descaling
Scale at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Definition: Iron oxide layer on hot steel
- Material loss: 1 – 3% of billet weight
- Effects: Die wear, surface pits
- Control: Short induction heating, descaling
What It Costs
Scale represents lost metal — typically 1–3% of billet weight, more with extended heating. It is also abrasive, accelerating die wear, and pressed into the surface it leaves pits that must be machined out.
Control and Removal
Short induction heating minimises formation. Descaling before forging, by high-pressure water or mechanical means, removes what has formed. Shot blasting after forging cleans the remainder and exposes the surface for inspection.
Topics covered on this page
- scale in forging
- forging scale removal
- oxide scale steel
- descaling forging
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is scale in forging?
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The iron oxide layer that forms on steel at forging temperature, costing material and causing surface pits if pressed in.
How much material does scale cost?
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Typically 1–3% of billet weight, rising with longer heating times.
How is scale removed?
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Descaling before forging by high-pressure water or mechanical means, and shot blasting afterwards.