Hot extrusion forces heated metal billets through a hardened steel die to form rods, tubes, and profiles. Using aluminum, steel, copper, and titanium alloys, the process provides uniform shapes for automotive, aerospace, and construction applications.
Hot extrusion is a deformation process in which heated billets are forced through a die to create long profiles with uniform cross‑sections. Billets are typically heated to 450–500°C for aluminum and up to 1200°C for steels, ensuring sufficient ductility and reduced forming forces. The process can be direct—where the ram pushes the billet toward the die—or indirect, which reduces friction by moving the die toward the billet. Common materials processed include aluminum alloys, copper, steels, and titanium. Tooling usually consists of Hot Work Tool Steel dies, extrusion stems, containers, dummy blocks, and shear rings designed to withstand high pressure, wear, and thermal cycling. Lubrication and die cooling are critical for surface quality and tool life. Hot extrusion enables the production of rods, tubes, bars, structural profiles, and precision components used in automotive, aerospace, construction, heat exchangers, and electrical applications where consistent properties and complex shapes are required.
BÖHLER W302 ISOBLOC is a 5% chromium steel and corresponds to material number 1.2344 (X40CrMoV5-1). Produced via the electroslag remelting process (ESR), this tool steel has very high hot toughness as well as very high hot hardness and a very good resistance against heat-checkings. The combination of these properties makes it a top performer in closed- and open-die forging as well as in high- and low-pressure die casting. In addition, this material has very good polishability and is therefore also often used as a molding material for plastic injection molds.
Read MoreBÖHLER W302 ISODISC is a 5% chromium steel and corresponds to material number 1.2344 (X40CrMoV5-1). This common tool steel has good hot toughness as well as a high hot hardness and a high resistance against heat-checkings. The combination of these properties makes it a standard choice in extrusion, forging and low-pressure die casting. This material is also available as W302 ISOBLOC which is a remelted grade with improved cleanliness, homogeneity and toughness.
Read MoreBÖHLER W403 VMR is a vacuum remelted material which was developed as a problem solver for tools for where a standard solution is no longer sufficient. The steel can be assigned to the 5% chromium steels and has a very high purity due to the special manufacturing technology. In addition, the increased molybdenum content leads to improved thermal resistance as well as wear resistance, which makes BÖHLER W403 VMR an all-rounder that is often used for highly stressed dies in the die casting sector. In addition, Böhler W403 VMR has outstanding polishability. For this reason, the steel is also popular as a molding material for plastic injection molds.
Read MoreBÖHLER W720 VMR is not a classic hot work tool steel, but an ultra-high strength maraging steel. Compared to quenched and tempered steels, the material generates its high strength not through a hardened and tempered martensitic structure with a high carbon content and secondary hardening carbides, but through the precipitation of intermetallic phases from a tough nickel martensitic matrix. BÖHLER W720 VMR corresponds to material number 1.6358 (X2NiCoMoTi18-9-5) and has proven to be ideally suited for many tool steel applications in cold and hot work (e.g., for extrusion stems) up to 450 °C.
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