Blacksmithing is the ancient craft of shaping metal into useful objects by heating it in a forge and hammering it on an anvil. One of the most common metals used in blacksmithing is steel. Knowing the proper steel temperature is crucial for blacksmiths to successfully shape the metal into the desired form. The ideal temperature range depends on the type of steel being worked, the specific blacksmithing technique being used, and the characteristics the blacksmith wants the final product to have.
Heating Steel for Blacksmithing
Steel is heated in a blacksmith’s forge, which burns fuel such as charcoal, coke or coal to generate the high temperatures needed to soften the metal. A common rule of thumb is that steel becomes workable in a range of 1500-2300°F (815-1260°C), but more specific temperature guidance depends on the carbon content of the steel.
Low Carbon Steel
Steels with less than 0.3% carbon are considered low carbon steels. This is a very common type of steel used by blacksmiths. It becomes soft enough to shape at around 1600-1800°F (870-980°C), but is often heated to 1900-2000°F (1040-1100°C) for more complex shapes. At this temperature, low carbon steel glows an orange color.
Medium Carbon Steel
Steels with 0.3-0.6% carbon are considered medium carbon. They require higher temperatures of 1800-2000°F (980-1100°C) to become soft and pliable. Medium carbon steel develops an orange-yellow glow at this temperature range.
High Carbon Steel
Steels with 0.6-1.4% carbon are high carbon steels. Extremely hard in their raw form, these steels need temperatures of 2000-2300°F (1100-1260°C) to be worked. At this temperature high carbon steel glows a bright yellow.
Judging Steel Temperature
Experienced blacksmiths often judge the temperature of steel by its color and appearance:
| Temperature | Appearance |
|---|---|
| 400-500°F (200-260°C) | Dark red, low heat |
| 500-800°F (260-425°C) | Red, medium heat |
| 800-1300°F (425-700°C) | Light cherry red |
| 1300-1500°F (700-815°C) | Bright cherry red |
| 1500-1800°F (815-980°C) | Orange |
| 1800-2300°F (980-1260°C) | Yellow |
| 2300-2800°F (1260-1540°C) | White |
As an additional check, some blacksmiths place a magnet against the heated steel. The magnet will cease to attract the steel when it reaches a dull red heat around 1400-1500°F.
Effects of Steel Temperature in Blacksmithing
Why is controlling steel temperature so important in blacksmithing? The heat softens the steel’s crystalline structure, enabling the blacksmith to hammer, bend, twist and shape it more easily. Higher temperatures are needed to work high carbon steels because of their harder composition.
The ideal working temperature allows steel to be shaped without becoming too soft. Steel heated past 2200°F (1200°C) can become “overcooked” and lose its internal strength and structure. It becomes more like putty, making it prone to cracking when hammered.
The blacksmith must also consider the desired characteristics of the final product:
Ductility
To make steel more malleable for significant shaping, heating to 2000-2100°F (1093-1150°C) softens it for bending, twisting or drawing out into thinner sections.
Toughness
For good combination of strength and flexibility, heating to 1800-2000°F (980-1093°C) allows steel to be hammered or stamped while retaining toughness.
Hardness
To maximize hardness, heating to lower temperatures followed by rapid quenching in oil or water produces a very hard but brittle metal. Martensitic steels are treated this way.
Grain Structure
Fine-grained steel results from working at lower temperatures or rapidly cooling from higher heats. Coarse grains are produced by slow cooling from peak temperatures. The blacksmith selects heating temperatures based on desired grain size.
Heating Tips for Blacksmiths
Here are some useful tips for blacksmiths heating steel:
– Use combustion air to control air/fuel mix and temperature of fire
– Pre-heat steel slowly to prevent cracking and warping
– Heat steel evenly and thoroughly to prevent weak spots
– Don’t over- or under-heat steel for the intended work
– Heat only small areas for localized shaping
– Normalize steel by slowly cooling from cherry red heat
– Always wear protective gear when working hot steel
Conclusion
Proper heating is the foundation of shaping steel in the blacksmithing process. Low carbon steels require 1600-2000°F (870-1093°C), while high carbon steels need 2000-2300°F (1093-1260°C) to become soft and workable. Judging temperature by color, magnetism and effects on steel allows the blacksmith to fine-tune the heating process. Mastering heat control enables precise, efficient forging as well as achieving the desired strength, hardness and ductility in the finished product. With skill and experience, blacksmiths gain the knowledge and “feel” needed to heat steel to the optimal temperature for their particular project.
