What are extrusion dies made of?

Our extrusion dies are made of (hot tool/work) steel. Steel is an alloy between iron and a limited carbon content(max 2%). There are more than 2300 species with different properties. It depends on the amount of carbon if the steel is more stiff/harsh, strong and bendable. A higher carbon content will lead to stiffer, but more breakable steel. A lower carbon content will lead to stronger, but more bendable steel. Below you will find a simplistic explanation of the steel production process.

How do they make it?

Firstly, iron ores have to be mined. The mining process takes place in China, Brazil, Australia, Russia or India. The mined iron ores will be washed and checked for their purity. Then, they will be transported to blast furnaces.

The next step is to make pig iron out of the iron ores. This process takes place in a blast furnace. The following materials are being used: Iron ores, coal and limestone. In addition, oxygen is being used. The temperature in the blast furnace is 2.200-2.300 ° C. The iron ores melt and seep down to the bottom of the furnace. At the bottom the iron ores are being called pig iron. Pig iron contains more carbon than iron. The pig iron will be transported to an oxysteel (oxygen steel) factory.

Pig iron contains too much carbon and breaks easily. That is why they have to reduce the amount of carbon. The pig iron is poured into a barrel (converter). Then oxygen is blown in the converter from above. Oxygen and carbon will become carbon monoxide and carbon dioxide. Pig iron has now become steel.

The liquid steel contains a lot of gas bubbles because of the process discussed above. Through a vacuum system the gas bubbles are being removed. Now the steel is ready for further processing.

What do we use?

For our extrusion dies we often use 1.2343 steel. Hot work/work steel with excellent toughness combined with high thermal stability, high resistance to thermal shocks, good thermal conductivity, limited water cooling possible. For the toughest applications we use ESR/ESU.

For large and complex dies we often use 1.2343 ESR/ESU steel, when a higher degree of material purity, homogeneity or toughness is needed. Combining the melting process with a secondary refining treatment set the standard properties of the 1.2343 ESR/ESU steel. The carbon content in the ESR/ESU steel increases the hardness. The ESR/ESU steel is tough and polishable. Another advantage is the good machinability. 

Key figures

Chemical composition

Heat treatment

Soft annealing

Stress relief annealing

Hardening