What Is Hot Forging?
Hot forging works steel above its recrystallisation temperature, typically 1,100–1,250°C. At that temperature the metal's resistance to deformation collapses, and it can be shaped heavily without hardening or cracking.
Hot forging works steel above its recrystallisation temperature, typically 1,100–1,250°C, where new strain-free grains continuously replace deformed ones so the metal never work hardens. This gives maximum formability for complex shapes at the cost of scale, shrinkage and ±0.5 mm tolerances.
- Temperature
- 1,100 – 1,250 °C for steel
- Tolerance
- ±0.5 mm class
- Surface finish
- Ra 12.5 – 25 µm
- Advantage
- Maximum formability
- Trade-off
- Scale, shrinkage, looser tolerance
What Is Hot Forging? at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Steel forged at 1,100–1,250 °C
- No work hardening above recrystallisation
- Tolerance around ±0.5 mm class
- Induction heating with pyrometer verification
Why Heat Changes Everything
Above recrystallisation, new strain-free grains continuously replace deformed ones. The metal never work hardens however much it is deformed, so complex shapes fill in a few blows rather than requiring intermediate annealing.
- 1,100–1,250 °C for steel
- No work hardening occurs
- Complex shapes in few blows
- Grain refined by the process
The Trade-Off
Heat brings scale formation, decarburisation risk and thermal shrinkage that must be predicted in the die. Tolerances land around ±0.5 mm rather than the ±0.1 mm cold forging achieves, so machining follows where accuracy is needed.
People also ask
What happens if steel is forged below the correct temperature?
Flow stress rises steeply, die loads spike, corners under-fill and internal bursts can form in the core. It also accelerates die wear substantially.
Does hot forging weaken the steel?
No, it refines grain and improves properties. Excessive temperature or long soaking can coarsen grain and decarburise the surface, which is why heating is controlled and verified.
Which parts are hot forged?
Most structural steel forgings — connecting rods, crankshafts, knuckles, yokes, flanges, gear blanks and anything with ribs, forks or deep cavities.
Topics covered on this page
- hot forging
- recrystallisation
- induction heating
- scale
- decarburisation
- thermal shrinkage
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
At what temperature is hot forging done?
+
1,100 to 1,250°C for carbon and alloy steel, above the recrystallisation temperature.
Why is hot forging the most common process?
+
It handles complex geometry at moderate cost, because heat makes the metal flow into detail that cold forming cannot fill.
What are the disadvantages of hot forging?
+
Scale formation, decarburisation risk and looser tolerances requiring subsequent machining.