Why Pit Type?
- Zero Bending: By hanging a long shaft vertically, gravity acts as a stabilizing force, keeping the part perfectly straight.
- Uniform Quenching: When you lift a hanging job out of a Pit furnace and drop it into a quench tank, the fluid hits all sides simultaneously, reducing the risk of "banana" warping.
Improved Machinability
Increased Ductility
It allows the metal to undergo massive deformation (like being drawn into a wire or pressed into a car body panel) withoutsnapping.
Stability
Annealed parts are less likely to “warp” during later heat
treatment steps because their internal stresses have been neutralized.
Safety
It prevents “hydrogen embrittlement” and other internal defects that can lead to sudden, catastrophic failure in structural parts.
Raw Material Production
Steel mills anneal wire, sheets, and bars before shipping them to manufacturers.
Castings & Forgings
Large engine blocks or gears are annealed after being
cast to ensure they don’t crack while being machined.
Welded Assemblies
Heavy structures are often “stress-relief annealed” near the weld joints to prevent failure.
Cold-Formed Parts
Copper tubing or brass casings are annealed so they can be bent or shaped multiple times without hardening and breaking.
Different Metal Annealing –
| Metal Type | Typical Annealing Temp (°C) | Cooling Method |
|---|---|---|
| Mild Steel | 850°C – 900°C | Slow Furnace Cool |
| Tool Steel | 760°C – 820°C | Very Slow Furnace Cool |
| Stainless Steel | 1050°C – 1100°C | Rapid Air or Water |
| Aluminum | 350°C – 400°C | Air Cool |
| Copper | 500°C – 600°C | Air Cool or Water Quench |
| Brass | 500°C | Air Cool |
Process in short
The annealing cycle consists of three distinct thermal stages:
Purpose :
Primary goal is to return the metal to its softest, most stable state:
