Tempering Colors Steel
Reference data and engineering information about tempering colors steel for material properties applications.
Overview
Engineering reference data for Tempering Colors Steel in material science and properties.
Key Formulas
Stress
Force per unit area.
Strain
Change in length per original length.
Hooke's Law
Stress proportional to strain in elastic region.
Thermal Expansion
Length change due to temperature.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Stress | Pa | |
| Strain | — | |
| Young's modulus | Pa | |
| Thermal expansion coefficient | 1/°C | |
| Temperature change | °C |
Tempering Process Details
The tempering process involves two distinct stages:
-
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.
-
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
Temperature(°F) | Temperature(°C) | Color | Typical Tool Applications |
|---|---|---|---|
| 600 | 316 | Scrapers, spokeshaves | |
| 560 | 293 | Screwdrivers, springs, gears | |
| 540 | 282 | Cold chisels, center punches | |
| 520 | 271 | Taps ≤ 1/4 inch | |
| 500 | 260 | Axes, wood chisels, drifts, taps ≥ 1/2 inch, nut taps, thread dies, press tools | |
| 480 | 249 | Twist drills, large taps, knurls | |
| 460 | 238 | Dies, punches, bits, reamers | |
| 450 | 232 | Twist drills for hard use | |
| 440 | 227 | Turning tools, lathe tools, scrapers, milling cutters, reamers | |
| 430 | 221 | Edge tools, reamers | |
| 420 | 216 | Knives, hammers |
Source: engineeringtoolbox.com
High-Temperature Carbon Steel Colors
Temperature(°F) | Temperature(°C) |
|---|---|
| 2192 | 1200 |
| 2012 | 1100 |
| 1922 | 1050 |
| 1796 | 980 |
| 1706 | 930 |
| 1598 | 870 |
| 1490 | 810 |
| 1400 | 760 |
| 1292 | 700 |
| 1202 | 650 |
| 1112 | 600 |
Source: engineeringtoolbox.com
Melting Points of Heat-Treating Baths
Material | Melting Point(°F) | Melting Point(°C) |
|---|---|---|
| 35% lead, 65% tin | 358 | 181 |
| 50% sodium nitrate, 50% potassium nitrate | 424 | 218 |
| Tin | 450 | 232 |
| Sodium nitrate | 586 | 308 |
| Lead | 620 | 327 |
| Potassium nitrate | 642 | 339 |
| 45% sodium chloride, 50% sodium sulfate | 1154 | 623 |
| Sodium chloride | 1474 | 801 |
| Sodium sulfate | 1618 | 881 |
| Barium chloride | 1760 | 960 |
Source: engineeringtoolbox.com
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.