Metal Annealing Temperature Calculator

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

1. Heat to the annealing temperature at a controlled rate
2. Soak (hold at temperature) to allow the grain structure to recrystallize
3. Cool slowly to prevent reintroduction of stresses

Annealing Temperatures by Metal

Aluminum is the row people get wrong most often. A full anneal on 6061 or 7075 is not “heat and let it cool on the bench”: pull the heat away too fast from 775°F and you have part-way solution treated the alloy instead of annealing it, so it comes out harder than it went in and keeps drifting for days as it naturally ages. The controlled 50°F per hour down to 500°F is what actually puts the alloy in the O temper.

Soak Time Formula

Soak Time (hours) = Maximum Cross-Section Thickness (inches) × Time Factor

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, because 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

Stainless is the opposite problem to carbon steel: it wants to get through the 1,500°F to 800°F window quickly. Dawdling in that band precipitates chromium carbides at the grain boundaries, which is what “sensitization” means, and a sensitized 304 weldment rusts at the heat-affected zone within months. Anything thicker than about 1/8 inch should go in the water.

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 it air cool. Both give the same result. Unlike steel, the cooling rate does not affect hardness in copper alloys.