In the field of metal processing, extrusion forming is a widely used process method, especially suitable for the processing of aluminum alloys, copper alloys, steel and other materials. As the core tool in the extrusion forming process, the performance of the mold directly affects product quality, production efficiency, and cost control. Therefore, it is crucial to make a reasonable choice of mold material when conducting extrusion forming.



1. Main Factors Affecting the Selection of Mold Materials



1. Working Temperature



During the extrusion process, the mold is subjected to high temperature and thermal cycles, especially in hot extrusion, where the temperature can reach over 500℃. Therefore, the mold material must have good high-temperature strength, thermal stability, and thermal fatigue resistance.



2. Material Hardness and Wear Resistance



During the extrusion process, there is significant friction between the billet and the mold, requiring the mold material to have high surface hardness and wear resistance to extend its service life.



3. Compressive Strength and Toughness



The mold bears a large pressure during operation, especially during cold extrusion, which can reach over 2000MPa. Therefore, the mold material needs to have sufficient compressive strength and certain toughness to prevent fracture or spalling.



4. Corrosion Resistance and Antioxidation



Under high temperature and poor lubrication conditions, the mold surface is prone to oxidation or corrosion, especially when processing certain special alloys, the corrosion resistance of the material is particularly important.



2. Common Mold Materials and Their Applications

　　1. Carbon Tool Steel (such as T10A)



Lower cost, suitable for low-speed, small-batch cold extrusion processes, but poor high-temperature performance, not suitable for hot extrusion.

　　2. Alloy Tool Steel (such as Cr12, Cr12MoV)



High hardness and wear resistance, widely used in cold extrusion molds. Proper heat treatment can improve its comprehensive performance.



3. High-speed Steel (such as W18Cr4V)



Good red hardness and wear resistance, suitable for medium and high-temperature extrusion and molds with complex shapes.



4. Hardmetal (such as YG type)



High hardness and wear resistance, suitable for high-precision, large-scale extrusion production, but expensive and poor toughness, use with caution.



5. Hot Work Die Steel (such as H13)



It is one of the most commonly used materials in hot extrusion, with good thermal strength, thermal fatigue resistance, and toughness, suitable for continuous operation under high-temperature environments.



3. Selection and Optimization Strategies for Materials



In practical applications, the selection of mold materials should be considered comprehensively in combination with specific process parameters, production batch, material characteristics, and other factors:



- For cold extrusion, Cr12MoV or D2 steel should be prioritized to ensure wear resistance and compressive strength;



- For hot extrusion, it is recommended to use H13 steel or 4Cr5MoSiV1 steel, taking into account thermal fatigue and strength;



- For high-precision products, consider using powder metallurgy high-speed steel or insert-type composite molds to improve mold life and stability;



- At the same time, a reasonable heat treatment process is crucial for improving mold performance, including quenching, tempering, and surface hardening treatment.



Conclusion



In summary, the selection of extrusion molding die materials is a systematic project, which not only relates to the service life of the mold but also directly affects the quality and production efficiency of the product. Enterprises should scientifically select mold materials according to their own process characteristics and development needs, and cooperate with advanced heat treatment technology and maintenance management to achieve efficient, economic, and stable production goals.