The melting point of steel lies between 1370 and 1540 degrees Celsius, depending on the carbon content and the alloy. Steel does not have a fixed melting point but a melting range, because it is a mixture of iron and other elements.
As a blacksmith, you rarely get close to that temperature: in a forging furnace you heat the steel to forging temperature, well below the melting point.
What is the melting point of steel?
The melting point of steel is between 1370 and 1540 degrees Celsius, with the exact value depending on the type of steel and its composition. Unlike a pure metal, steel does not melt at one fixed point, but over a range of temperatures.
This is because steel is an alloy. The amount of carbon and the presence of elements such as manganese, chromium, or nickel determine where within that range your steel begins to melt. For most common types of steel, you can assume a melting point around 1450 degrees Celsius.
Why does steel have a melting range?
Steel has a melting range because it consists of multiple components that do not all become liquid at the same temperature. Iron, carbon, and the other alloying elements melt gradually, creating a zone where solid and liquid steel coexist.
At the bottom of this range, the first parts become liquid. This is called the solidus temperature. At the top, the steel is completely melted, which is the liquidus temperature. Between these two boundaries, your material is partly solid and partly liquid, which is important for casting and welding.
How does carbon content affect the melting point of steel?
The carbon content lowers the melting point of steel: the more carbon, the lower the melting temperature. Pure iron melts at 1538 degrees Celsius, but as soon as carbon is added, that value drops.
As a result, high-carbon tool steel melts earlier than low-carbon structural steel. Other elements also shift the range. Chromium and nickel in stainless steel not only change the rust resistance but also the temperature at which the steel becomes liquid.
Melting point per steel type
The melting point differs per type of steel, because each type has its own mixture of carbon and alloying elements. The differences are not large, but they certainly matter in casting, welding, and heat treatment.
Melting point of stainless steel
Stainless steel melts around 1510 degrees Celsius, slightly below the melting point of pure iron. The chromium and nickel contents that make the steel rust-resistant subtly shift the melting range. Depending on the exact quality, the melting point of stainless steel is between 1400 and 1530 degrees Celsius.
Melting point of hardened steel
The melting point of hardened steel is virtually the same as that of the underlying carbon steel. Hardening changes the microstructure and hardness of the steel, not its chemical composition. Therefore, the temperature at which the material becomes liquid remains within the normal range for carbon steel, between 1370 and 1500 degrees Celsius.
Melting point of structural steel like S235
Structural steel like S235, formerly known as steel 37, has a low carbon content and therefore melts high in the range. Its melting point is close to that of pure iron, around 1500 degrees Celsius. This is the steel found in beams, pipes, and sheet metal.
Melting point of steel versus iron
Pure iron melts at 1538 degrees Celsius, higher than most types of steel. As soon as iron absorbs carbon and becomes steel, its melting point drops. Thus, pure iron has a higher melting temperature than the steel it forms.
In practice, you hardly notice this difference. When forging, both iron and steel are heated to forging temperature and are not brought close to their melting point. The distinction is primarily relevant in casting, where the metal is made completely liquid.
Melting point or forging temperature: what do you need for forging?
To forge, you need the forging temperature, not the melting point of steel. You heat the steel until it is glowing and malleable, so you can shape it under the hammer. Liquid steel is the last thing you want: then your workpiece is lost.
The forging temperature is hundreds of degrees below the melting point. You bring the steel into a plastic state where the grain structure moves with your blows, while the material retains its shape.
Forging temperature of carbon steel
Carbon steel is usually forged between 900 and 1250 degrees Celsius, well below the melting temperature. Within this window, the steel is soft enough to deform without tearing. Stainless steel requires a higher forging temperature, often between 1100 and 1300 degrees Celsius, and is more difficult to shape under the hammer than plain carbon steel.
Achieving the right heat in your forging furnace or forge fire
The right forging heat is achieved in a gas-fired furnace or a coal-fired forge, both ample for forging temperature. A gas furnace maintains a consistent temperature, while with a forge fire you build up a more intense, localized heat. Which one you choose depends on your work and your workshop.
The temperature is read from the glow color of the steel. Dark red begins between 500 and 600 degrees Celsius, while steel at forging heat glows orange-yellow, between 1000 and 1250 degrees Celsius. Always assess that color in subdued daylight, not in bright sun or artificial light.
From melting point to your first forging work
You don't need to reach the melting point of steel to start forging; you need the right forging heat and the right tools. A furnace or fire that reaches forging temperature, an anvil and a hammer will get you further than any melting temperature. If you want everything in one go, check out the completeforging packages from Parrot Shopping, put together as your guide in the art of forging.
