Cold Extrusion Die Steel and Cold Extrusion Dies

During cold extrusion the concave die is often subjected to pre-compressive stresses in the jacket and tensile stresses during extrusion, while the convex die is subjected to enormous compressive stresses. The heat generated during the deformation of the workpiece is also partially absorbed by the die, so the die material also needs to have a certain high-temperature hardness and thermal stability. In addition, the surface of the die often produces abrasion and extrusion, thus causing the size and shape of the workpiece to change, surface roughness increases, making the die failure. The load borne by the cold extrusion die depends on the material strength of the extruded workpiece and the degree of work hardening and deformation of the workpiece extrusion process.

Extrusion of softer aluminium alloy workpiece with a small die, its concave die can be made of carbon tool steel; extrusion of high-strength aluminium alloy, carbon steel and low alloy steel workpiece cold extrusion die, generally used in the alloy die steel manufacturing (such as Cr5Mo1V and so on, hardness of HRC56 ~ 58). Production batch is not big cold extrusion convex die and roof rod materials, generally used in the alloy cold working die steel manufacturing; for the production of large quantities of workpiece cold extrusion convex die, in order to improve its compressive strength and wear resistance, the general choice of high alloy die steel (such as Cr12MoV, Cr12Mo1V1, 7Cr7Mo3V2Si, etc.) or high-speed steel, matrix steel (such as W6Mo5Cr4V2, 6W6Mo5Cr4V, etc.) are manufactured.

Good lubrication conditions are the main measures to reduce the wear and tear of cold extrusion moulds. For ferrous metal cold extrusion products, often using phosphating and saponification treatment to improve lubrication conditions. In actual production, improper lubrication conditions will cause early failure of cold extrusion die.
When the extrusion workpiece is very large, such as extrusion of steel more than 100,000 pieces, extrusion of light alloy workpiece more than 500,000 pieces, and sometimes the use of cemented carbide manufacturing mould inserts. When extrusion deformation resistance is very high alloy steel workpiece or counter-extrusion of large ring-shaped workpiece, can also be used to manufacture carbide cold extrusion convex die inserts, convex die of the general selection of high-strength structural steel coat manufacturing (heat treatment hardness of HRC55 ~ 58).