Tempering Colors Steel

Overview

Engineering reference data for Tempering Colors Steel in material science and properties.

Key Formulas

Stress

$\sigma = \frac{F}{A}$

Force per unit area.

Strain

$\varepsilon = \frac{\Delta L}{L_0}$

Change in length per original length.

Hooke's Law

$\sigma = E \varepsilon$

Stress proportional to strain in elastic region.

Thermal Expansion

$\Delta L = \alpha L_0 \Delta T$

Length change due to temperature.

Variables

Symbol	Description	Unit
$\sigma$	Stress	Pa
$\varepsilon$	Strain	—
$E$	Young's modulus	Pa
$\alpha$	Thermal expansion coefficient	1/°C
$\Delta T$	Temperature change	°C

Tempering Process Details

The tempering process involves two distinct stages:

1. Forging and Hardening: The tool end is heated to a bright red color, forged, then quenched in cold water and cooled until touchable. The tool is then sharpened and polished.

2. Tempering: The tool is reheated to a specific tempering temperature (as indicated in the tables below) to relieve internal stresses and achieve the desired balance of hardness and toughness.

Carbon Steel Tempering Colors and Tool Applications

High-Temperature Carbon Steel Colors

Melting Points of Heat-Treating Baths

Important Notes on Tempering

• Heat-Treating Mediums: Besides air furnaces, oil baths, salt baths, lead baths, and sand baths are also used extensively for tempering steel tools.
• Oxide Film Formation: When steel is heated in an oxidizing atmosphere (like air), a film of oxide forms on the surface, causing the color to change as temperature increases.
• Material Dependency: The tempering colors are affected to some extent by the composition of the steel, so this color-temperature method may not be perfectly dependable across all steel grades.

Interactive Charts

References

• Original Source