Wiki-Annealing

Annealing is an essential heat treatment process applied to metal products, including knives. This process has the following characteristics and purposes:

Objectives and Effects

  1. Softening: Makes the metal softer to improve workability.
  2. Removal of Internal Stress: Eliminates internal stresses caused by work hardening.
  3. Structure Homogenization: Evens out the metal structure, achieving a stable state.
  4. Improved Ductility: Enhances the metal's stretchability.

Process

  1. Heating: Metal is heated to a specific temperature.
  2. Holding: The temperature is maintained for a certain period.
  3. Cooling: The metal is slowly cooled, typically in a furnace.

Types

Annealing comes in several types, depending on the intended purpose:

  1. Full Annealing: The most common treatment, softening the structure and improving ductility.
  2. Spheroidizing Annealing: Essential for high-carbon tool steel, alloy tool steel, and bearing steel.
  3. Stress Relief Annealing: Removes residual stress and realigns crystal grains.

Applications in Knives

In knife manufacturing, annealing plays the following roles:

  1. Enhanced Workability: Softens the steel to facilitate forming and machining.
  2. Structural Adjustment: Includes spheroidizing annealing, crucial before quenching high-carbon steel.
  3. Stabilization: Brings the metal to its most stable state.

Annealing is a critical process for ensuring the quality and performance of knives, serving as the foundation for subsequent heat treatments such as quenching and tempering.

Related websites
The Art of Making Japanese Knives: Detailed Process | KIREAJI