What are the different properties of different materials for die steel?

With the rapid development of social economy, die steel has also been widely used. Die steel is a steel type used to make cold die, hot forging die, die casting die and other dies. Moulds are the main processing tools for manufacturing parts in industrial sectors such as machinery manufacturing, radio instruments, motors, electrical appliances, etc. Next, Dongqi Die Steel Editor will share with you the different properties of different materials of die steel.

1. Classification and Development of Die Steel

Mold steel is mainly divided into three categories, cold work mold steel, hot work mold steel, plastic mold steel.

At present, most of the cold work die steels commonly used in China are carbon tool steel (T7A, T8A, T10A, T12A), low alloy tool steel CrWMn, high carbon high chromium steel Cr12, Cr12MoV, high speed steel W18Cr4V, W6Mo5Cr4V2 and other traditional typical steels. Species, but also introduced. A variety of new steel grades have been developed to meet the ever-increasing requirements.

Hot work die steel is mainly used to manufacture molds for pressure processing under high temperature conditions, such as hot forging molds, hot extrusion molds, die casting molds, hot upsetting molds, etc. With the increase of forging mechanical capabilities and the complexity of the shape of the processed parts, especially the difficulty of processing the processed materials, such as processing titanium alloys, high alloy steels, stainless steels and heat-resistant steels, molds tend to be large and high-performance. The performance requirements for hot work die steel are also getting higher and higher. The traditional hot work die steels 5CrNiMo and 5CrMnMo steel have a short service life due to thermal strength, low thermal stability, easy cracking and collapse.

2. Punching die

Punching die is a special process equipment for processing metal or non-metal into parts or semi-finished products in cold stamping process. It is a mold that separates materials along closed or open contour lines. Such as blanking die, punching die, cutting die, cutting die, trimming die, cutting die, etc.

When the material to be punched is hard or the deformation resistance is large, the convex and concave dies of the punch should be made of materials with good wear resistance and high strength. The guide column guide sleeve requires wear resistance and good toughness, so it is mostly carburized and quenched on the surface of low-carbon steel. As another example, the main disadvantage of carbon tool steel is poor hardenability. When the cross-sectional size of the die part is large, the center hardness after quenching is still low, but when working on a press with a large number of strokes, due to its resistance Good impact is an advantage. For the fixed plate and unloading plate parts, not only must they have sufficient strength, but also they need to be deformed little during the work. In addition, cold treatment and cryogenic treatment, vacuum treatment and surface strengthening methods can also be used to improve the performance of mold parts. For cold extrusion dies with poor working conditions of convex and concave dies, die steel with sufficient comprehensive mechanical properties such as hardness, strength, toughness, and wear resistance should be selected, and it should have certain red hardness and thermal fatigue strength. .

Therefore, there should be a certain choice of materials in the manufacture of punching dies. The types of commonly used die working part materials are: carbon tool steel, low alloy tool steel, high carbon high chromium or medium chromium tool steel, medium carbon alloy steel, high speed Steel, base steel and cemented carbide, steel-bonded cemented carbide, etc.

1. Carbon tool steel: The carbon tool steel that is widely used in molds is T8A, T10A, etc. The advantages are good processing performance and low price. However, the hardenability and red hardness are poor, the heat treatment deformation is large, and the bearing capacity is low.

2. Low-alloy tool steel: Low-alloy tool steel is based on the carbon tool steel with an appropriate amount of alloying elements added. Compared with carbon tool steel, the tendency of quenching deformation and cracking is reduced, the hardenability of the steel is improved, and the wear resistance is also better. The low-alloy steels used for manufacturing molds include CrWMn, 9Mn2V, 7CrSiMnMoV, 6CrNiSiMnMoV, etc.

3. High-carbon and high-chromium tool steel: Commonly used high-carbon and high-chromium tool steels are Cr12, Cr12MoV, Cr12Mo1V1, which have good hardenability, hardenability and wear resistance. Deformed die steel is second only to high-speed steel in carrying capacity. However, the carbide segregation is serious, and it must be repeatedly upset (axial upsetting, radial drawing) to forge to reduce the unevenness of the carbide and improve the performance.

4. High-carbon medium-chromium tool steel: The high-carbon medium-chromium tool steels used for molds are Cr4W2MoV, Cr6WV, Cr5MoV, etc. They have low chromium content, less eutectic carbides, uniform carbide distribution, and small heat treatment deformation. Has good hardenability and dimensional stability. Compared with the high carbon and high chromium steel with relatively severe carbide segregation, the performance has been improved.

5. High-speed steel: High-speed steel has the highest hardness, wear resistance and compressive strength of the mold steel, and the bearing capacity is very high. Commonly used in the mold are W18Cr4V and W6Mo5 Cr4V2 with less tungsten content and 6W6Mo5 Cr4V, a carbon-reduced and vanadium-reduced high-speed steel developed to improve toughness. High-speed steel also needs to be forged to improve its carbide distribution.

6. Matrix steel: Add a small amount of other elements to the basic composition of high-speed steel, and appropriately increase or decrease the carbon content to improve the performance of the steel. Such steels are collectively called matrix steels. They not only have the characteristics of high-speed steel, have a certain wear resistance and hardness, but also have better fatigue strength and toughness than high-speed steel. They are high-strength and tough cold-working die steels, but the material cost is lower than that of high-speed steel. The base steels commonly used in molds are 6Cr4W3Mo2VNb, 7Cr7Mo2V2Si, 5Cr4Mo3SiMnVAL and so on.