Metal Annealing Temperature Calculator
Find the correct annealing temperature, soak time, and cooling method for steel, copper, aluminum, and brass.
Annealing is a heat treatment process that softens metal by relieving internal stresses and restoring ductility. After cold working (bending, hammering, rolling, drawing), metal becomes hard and brittle through work hardening. Annealing reverses this, allowing further forming without cracking.
The Annealing Process
- Heat to the annealing temperature at a controlled rate
- Soak (hold at temperature) to allow the grain structure to recrystallize
- Cool slowly to prevent reintroduction of stresses
Annealing Temperatures by Metal
| Metal / Alloy | Annealing Temp (°F) | Annealing Temp (°C) | Soak Time | Cooling Method |
|---|---|---|---|---|
| Mild Steel (1018) | 1,550–1,600°F | 843–871°C | 1 hr/inch | Furnace cool (very slow) |
| Medium Carbon (1045) | 1,450–1,550°F | 788–843°C | 1 hr/inch | Furnace cool |
| High Carbon (1095) | 1,400–1,475°F | 760–802°C | 1 hr/inch | Furnace cool |
| Tool Steel (O1) | 1,400–1,450°F | 760–788°C | 1 hr/inch | Furnace cool, max 40°F/hr |
| Tool Steel (D2) | 1,600–1,650°F | 871–899°C | 1 hr/inch | Furnace cool, max 25°F/hr |
| Stainless 304 | 1,850–2,050°F | 1,010–1,121°C | 1 hr/inch | Air cool or water quench |
| Stainless 316 | 1,850–2,050°F | 1,010–1,121°C | 1 hr/inch | Air cool or water quench |
| Copper (pure) | 700–1,200°F | 371–649°C | 15–30 min | Air cool or water quench |
| Brass (C260) | 800–1,100°F | 427–593°C | 30 min | Air cool |
| Bronze (C510) | 900–1,250°F | 482–677°C | 30 min | Air cool |
| Aluminum 6061 | 775°F | 413°C | 2–3 hours | Air cool, then age at 350°F |
| Aluminum 7075 | 775°F | 413°C | 2–3 hours | Air cool, then age at 250°F |
| Titanium Gr.2 | 1,200–1,400°F | 649–760°C | 1 hr/inch | Air cool |
Soak Time Formula
Soak Time (hours) = Maximum Cross-Section Thickness (inches) × Time Factor
| Material Category | Time Factor |
|---|---|
| Carbon steel | 1.0 hr per inch |
| Alloy / tool steel | 1.0 hr per inch (min 1 hour) |
| Stainless steel | 1.0 hr per inch |
| Copper / brass | 0.5 hr per inch (min 15 min) |
| Aluminum | 2.0 hr per inch (min 2 hours) |
Worked Example — Annealing a 1095 Steel Knife Blank (0.125" thick)
Annealing temperature: 1,450°F (788°C). Thickness: 0.125 inches (3.2 mm). Soak time: 0.125 × 1.0 = 0.125 hours = 7.5 minutes. Minimum practical soak: 30 minutes (to ensure uniform temperature throughout).
Cooling: Close the forge and let the blade cool inside overnight. Never remove and air-cool carbon steel during annealing — it will partially harden instead of softening.
After annealing, the Rockwell hardness of 1095 drops to approximately HRC 15–20, making it soft enough to file, drill, and shape by hand.
Cooling Rate Guidelines
| Metal | Maximum Cooling Rate | Method |
|---|---|---|
| Carbon steel | 40°F/hr (22°C/hr) | Furnace cool or bury in vermiculite |
| Tool steel (O1, D2) | 25°F/hr (14°C/hr) | Furnace cool only |
| Stainless steel | Fast cool OK | Air cool or water quench |
| Copper | Fast cool OK | Air cool or quench (no difference) |
| Aluminum | Fast cool OK | Air cool |
Quick Anneal for Copper and Brass
Copper and brass can be annealed with a simple torch. Heat to a dull red (barely visible in dim light), then quench in water or let air cool — both methods produce the same result. Unlike steel, the cooling rate does not affect hardness in copper alloys.