Heat Treating
 

Hardening

Purpose: Increases surface or core hardness to resist wear.

• Process: Typically involves heating and rapid quenching. Sometimes uses surface treatments (like flame or induction hardening).

• Benefits:

  • Improved wear and abrasion resistance

  • Extended part life under load or friction

  • Enhanced fatigue strength

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Stress Relieving

Purpose: Relieves internal stresses from welding, machining, or cold working without significantly altering structure.

• Process: Heat below the critical temperature, hold, and then air cool.

• Benefits:

  • Reduces distortion risk

  • Improves dimensional stability

  • Enhances fatigue resistance

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Tempering

Purpose: Reduces brittleness while retaining hardness after quenching.

• Process: Reheat quenched metal to a lower temperature, then cool it at a controlled rate.

• Benefits:

  • Improves toughness

  • Reduces internal stresses

  • Makes hardened steel more durable

Annealing

Purpose: Softens metal, improves ductility, refines grain structure, and removes internal stresses.

• Process: Heat metal to a specific temperature, hold it, then cool slowly (usually in a furnace).

• Benefits:

  • Easier machining and forming

  • Increases toughness

  • Reduces hardness

  • Restores ductility after cold working

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Quenching

Purpose: Rapid cooling to increase hardness.

• Process: Heat metal above critical temperature, then rapidly cool in water, oil, or air.

• Benefits:

  • Greatly increases hardness

  • Locks in high-strength microstructures

  • Prepares metal for further tempering