Among the four major manufacturing processes, stamping is extremely important. During the stamping process, the quality of the stamping die is a critical step. Die failures often cause production stoppages, affecting the quality of stamped parts and production lead times. In addition to the process itself, material selection is also a crucial factor in stamping die production, and the die material is key to extending its service life. Below, Zhejiang Baifudu Electromechanical Editor introduces some common stamping die manufacturing materials.
Materials used for producing stamped parts include high-speed steel, carbon tool steel, alloy tool steel, cemented carbide, steel-bonded cemented carbide, zinc-based alloy, low-melting-point alloy, aluminum bronze, and polymer materials. Currently, most stamping die materials are steel.
1. Carbon Tool Steel
Carbon tool steels such as T8A and T10A are used for stamping dies. They feature good machinability and low cost, but have poor hardenability and red hardness, significant heat treatment deformation, and low load-bearing capacity.
2. Low-Alloy Steel
Low-alloy steel is based on carbon tool steel with the addition of appropriate alloying elements. Compared with carbon tool steel, it exhibits less quenching deformation, better hardenability, and improved wear resistance after quenching. Low-alloy steels used for stamping dies include CrWMn, 9Mn2V, 7CrSiMnMoV (designation CH-1), and 6CrNiSiMnMoV (designation GD).
3. High-Carbon High-Chromium Tool Steel
Cr12 and Cr12MoV, as well as Cr12Mo1V1 (designation D2), are common high-carbon high-chromium tool steels with good hardening properties and minimal heat treatment deformation. They are high-wear-resistance, micro-deformation die steels with load-bearing capacity second only to high-speed steel. However, they suffer from severe carbide segregation and must undergo repeated upsetting and drawing (axial upsetting). Through forging, the non-uniformity of carbides can be reduced, improving service performance.
4. Medium-Chromium High-Carbon Tool Steel
High-carbon medium-chromium tool steels mainly include Cr4W2MoV, Cr6WV, and Cr5MoV. They have lower chromium content, uniform carbide distribution, minimal heat treatment deformation, good hardenability, and excellent dimensional stability during processing. Results show that compared with high-carbon high-chromium steels with more severe carbide segregation, their performance is improved.
5. High-Speed Steel
Among high-speed steels, this type offers the highest hardness, wear resistance, compressive strength, and load-bearing capacity. Examples include W18Cr4V (designated 8-4-1), tungsten-containing W6Mo5Cr4V2 (designated 6-5-4-2; Japanese brand SKH51, American brand M2), and 6W6Mo5Cr4V (designated 6W6, also known as low-carbon M2) for enhanced toughness.
6. Matrix Steel
By adding small amounts of other elements to the basic composition of high-speed steel and appropriately increasing the carbon content, the steel's properties can be improved. Such steels are collectively referred to as matrix steels. They not only exhibit high wear resistance and hardness but also offer better fatigue strength and toughness than high-speed steel. They are high-toughness cold-work die steels with lower material costs than high-speed steel. Common matrix steels used in stamping dies include 6Cr4W3Mo2VNb (designated 65Nb), 7Cr7Mo2V2Si (designated LD), and 5Cr4Mo3SiMnVal (designated 012Al).
7. Carbides and Steel-Bonded Carbides
Carbides offer high hardness and wear resistance but have poor bending strength and toughness. Tungsten-cobalt alloys are used as cemented carbides for dies. For dies requiring high wear resistance with low impact, low-cobalt-content carbides are suitable. For dies subjected to impact, high-cobalt-content carbides are recommended.
Steel-bonded carbides are produced by powder metallurgy sintering, using a small amount of alloy element powders (such as chromium, molybdenum, tungsten, vanadium, etc.) as binders and titanium carbide or tungsten carbide as the hard phase. Steel-bonded carbides use steel as the matrix, overcoming the drawbacks of cemented carbides such as poor toughness and difficult machinability. They can be cut, welded, forged, and heat-treated. Steel-bonded carbides contain a high proportion of carbides. After quenching, steel-bonded carbides exhibit lower hardness and wear resistance compared to cemented carbides, but still achieve high hardness, reaching 68–73 HRC.
The above content relates to materials used in stamping die manufacturing. The cost of stamping dies is high, typically accounting for 1/4 to 1/5 of the total cost of stamped parts. The cost of a single repair can exceed 70% of the original die cost, or the die life may be near its end. If the repair process is too complex, the repair cost is excessively high, and the difficulty inevitably leads to prolonged maintenance cycles, severely impacting normal production of stamped parts, then the die should be identified as prematurely failed and scrapped, and removed from the die set. It is hoped that the above information will be helpful to readers.