What steel is used for aluminum extrusion dies?

What are extrusion dies made of?
Our extrusion dies are made of hot work/tool steel. Steel is an alloy composed of iron and a limited amount of carbon (maximum 2%). There are over 2,300 different species with varying properties. The hardness, toughness, and flexibility of the steel depend on the carbon content. A higher carbon content results in harder but more brittle steel, while a lower carbon content produces tougher but more flexible steel. Below, you will find a simple explanation of the steel production process.

How is it done?
First, iron ore must be mined. The mining process is carried out in countries like China, Brazil, Australia, Russia, or India. The mined iron ore is then cleaned and checked for purity before being transported to a blast furnace.

The next step is to produce pig iron from iron ore. This process takes place in the blast furnace, using materials such as iron ore, coal, and limestone, with oxygen also being utilized. The temperature inside the furnace reaches 2,200-2,300°C. The iron ore melts and trickles down to the bottom of the furnace, where it is collected as pig iron. Pig iron contains more carbon than regular iron and is then transported to a basic oxygen steelmaking (BOS) plant.

Pig iron contains excessive carbon, making it brittle, so the carbon content must be reduced. Pig iron is poured into a converter (vessel), and oxygen is blown in from above. The oxygen reacts with the carbon to form carbon monoxide and carbon dioxide, transforming the pig iron into steel.

Due to the aforementioned process, the molten steel contains many bubbles. A vacuum system is used to remove these bubbles, and now the steel is ready for further processing.

What do we use?
For our extrusion dies, we often use 1.2343 steel. This hot work/tool steel offers excellent toughness, high thermal stability, good resistance to thermal shock, good thermal conductivity, and limited water-cooling capability. For the most demanding applications, we use ESR/ESU steel.

For large and complex dies, we typically use 1.2343 ESR/ESU steel when a higher degree of material purity, uniformity, or toughness is required. The combination of the melting process and secondary refining sets the standard performance of 1.2343 ESR/ESU steel. The carbon content in ESR/ESU steel increases hardness, making it tough and polishable. Another advantage is its good machinability.

Key Data

• Chemical Composition
• Heat Treatment
  • Annealing
  • Stress Relieving Annealing
  • Quenching