D2 Steel Technical Overview

D2 Steel Technical Overview: It is a high-carbon, high-chromium, cold-work tool steel. It is particularly known for its good wear resistance and deep hardening capabilities. When we discuss D2 steel specifications, we will talk about the D2 steel composition, heat treatment and hardness, applications and performance, comparison of D2 steels with other D-series steels, common situations where D2 steel needs to be considered for substitution, and disadvantages of D2 steel.

1. Chemical Composition

2. Heat Treatment And Hardness Specifications

2.1 Heat Treatment of D2 Steel

• Annealing: This softens steel for machining. Typically, the temperature is between 870 and 900 °C (1600 to 1650 °F), and the steel is slowly cooled in the furnace.
• Hardening (Austenitizing): Heat the steel to its austenitizing temperature at 980 to 1025 °C (1800 to 1875 °F). By soaking at this temperature, austenite forms, and carbides dissolve. We strongly recommend preheating before reaching the final austenitizing temperature. This is done to heat uniformly to reduce the risk of cracking due to the low thermal conductivity of D2 steel. Usually, the preheat temperature is 650 to 700 °C (1200 to 1300 °F).
• Quenching: D2 steel is typically air-hardened by cooling in air because of its high hardenability. Oil quenching may also be used for heavier steel or to achieve maximum hardness. Quenching transforms the austenite into martensite, resulting in the goal of high hardness.
• Tempering: After quenching, the hardened D2 steel is tempered to reduce brittleness. The tempering temperature is usually between 205 and 540 °C (400 and 1000 °F). The final hardness will depend on the specific tempering temperature. We recommend double tempering to ensure the complete transformation of retained austenite and improve toughness.

2.2 Hardness of D2 Steel

After proper hardening and tempering, D2 steel’s hardness is in the range of 58 to 64 HRC (Rockwell C scale).

Typically, the hardness achieved as-quenched after air or oil quenching from the austenitizing temperature is toward the high end of this range.

Tempering at higher temperatures in the recommended range will result in a slight decrease in hardness but an increase in toughness. For example, tempering at temperatures closer to 540 °C (1000 °F) will yield a lower hardness compared to tempering at 205 °C (400 °F).

However, this is quite an involved and detailed matter, and the specific heating rates, soaking times, quenching methods, tempering until falling temperature, etc., should be well controlled; otherwise, you may not get the desired hardness or other properties.

3. Specification of D2 Applications And Performance

Firstly, as we mentioned, D2 steel is a high-carbon, high-chromium steel. These alloy elements render D2 steel highly hard and wear-resistant.

Secondly, the high chromium content improves the hardenability of D2 steel. Hardenability is the ability of a steel to be hardened by heat treatment. This uniform deep hardening provides wear and deformation resistance in demanding applications.

Based on these properties, D2 Steel is utilized widely in cold work tooling applications.

3.1 Blanking Dies

D2 steel is known for its excellent wear resistance and hardness, making it perfect for dies that cut or punch forms out of metal sheets. Blanking die for different materials from thinner gauge materials (t≤3mm) to thicker sheets. Moreover, it is especially fit for blanking dies for abrasive material, such as silicon steel sheet, aluminum sheets, etc.

3.2 Piercing Dies

Like blanking, D2 steel’s high hardness and wear resistance make it a good choice for piercing holes in sheet metal.

3.3 Cold Forming Dies

D2 steel’s ability to withstand high compressive stresses and resist wear makes it suitable for cold forming operations at room temperature. This includes applications such as cold extrusion and cold heading, which need to maintain their shape and resist wear under big pressure.

3.4 Drawing Dies

Dies are involved in the sheet metal drawing process. D2 steel is well suited to resist wear associated with the friction experienced in drawing.

3.5 Thread Rolling Dies

Dies are involved in the sheet metal drawing process, and D2 steel is well suited to resist wear associated with the friction experienced in drawing.

3.6 Forming Rolls

In rolling operations where metal is shaped by passing, D2 steel’s hardness ensures the rolls maintain their profile and resist wear over long run production

3.7 Gauges

When applying measuring tools, D2 steel’s dimensional stability after heat treatment and its high wear resistance capabilities are crucial for maintaining accuracy for a long time.

3.8 Slitters and Shear Blades

The sharp edges of slitting and shearing tools made from D2 steel retain their sharpness for long periods due to the material’s high hardness and wear resistance. This applies to various thicknesses of materials, but we have to consider both balance and toughness for thicker materials.

We must remember that while D2 steel offers excellent wear resistance and hardness for cold work, its toughness should be a considered for applications involving very high impact loads or significant bending stresses.