D2 steel Vs. 4140: What are the difference?

D2 steel Vs. 4140: Stal narzędziowa D2 I stal 4140 are both important ferrous alloys, but they belong to different classifications and are designed for distinct applications, exhibiting unique properties and requiring specific heat treatments.

Kompozycja

Element	D2 Tool Steel (%)	4140 Steel (%)
Węgiel (C)	1.40 – 1.60	0.38 – 0.43
Chrom (Cr)	11.00 – 13.00	0.80 – 1.10
Molibden (Mo)	0.70 – 1.20	0.15 – 0.25
Mangan (Mn)	0.10 – 0.60	0.75 – 1.00
Wanad (V)	0.50 – 1.10	–
Krzem (Si)	0.10 – 0.60	0.15 – 0.35
Fosfor (P)	≤ 0,03	≤ 0,035
Siarka (S)	≤ 0,03	≤ 0,040

Właściwości mechaniczne

1. Twardość. Twardość stali D2 is 60 to 62 HRC after heat treatment. Although 4140 steel can also achieve high hardness through heat treatment, it is lower than that of D2 steel. Quenched and tempered 4140 can range from 235 HB to 578 HB, depending on the tempering temperature.
2. Hartowność. D2 is an air-hardening steel, meaning it can be hardened by cooling in air, which minimizes distortion. 4140 steel has moderate hardenability. While it can be air-hardened in thin sections, it is typically oil-quenched in practice for through-hardening.
3. Wytrzymałość. D2 steel has poor toughness. However, 4140 steel has improved toughness. Its toughness properties are affected by tempering temperature; for instance, tempering between 230 and 370°C (450 to 700°F) is usually avoided to prevent blue brittleness.
4. Odporność na zużycieStal D2 ma wyjątkowo wysoką nosić resistance, higher than that of 4140 steel. 4140 Steel can significantly improve its wear resistance through surface hardening treatments such as nitriding or induction hardening.
5. Obróbka skrawaniem. D2 has poor machinability, with a machinability rating of 45, compared to 1% carbon steel, which is rated at 100. 4140 has good machinability, especially resulfurized versions like SAE 1140.
6. Stabilność wymiarowa. D2 steel undergoes minimal deformation during heat treatment. When air quenched, it expands or contracts approximately 0.0005 inches per inch. (0.0005 mm/mm). 4140 Steel’s dimensional stability is generally good, but like all steels, it is subject to distortion during quenching, especially with higher carbon content, which can increase the probability of cracking.

Obróbka cieplna

• Heat Treat D2 Steel:
  • Wyżarzanie: Proper annealing is crucial for machinability.
  • Hartowanie: Typically air-hardened. Austenitizing temperatures range from 980 to 1025 °C (1800 to 1875 °F).
  • Ruszenie: Generally double-tempered. Tempering at low temperatures (e.g., 200 °C) can achieve maximum hardness.
  • Obróbka powierzchni: Can be ion nitrided to significantly increase surface hardness and wear resistance.
• 4140 Steel:
  • Normalizowanie: Heat to 845-925 °C (1550-1700 °F) and air cool.
  • Wyżarzanie: Heat to 830-870 °C (1525-1600 °F) and cool slowly in the furnace.
  • Gaszenie: Usually oil-quenched from 855 °C (1575 °F). Conventional and fast oils provide equivalent properties for this steel. Oil quenching results in a microstructure of tempered martensite.
  • Ruszenie: Can be tempered at various temperatures from 205-705 °C (400-1300 °F) to achieve desired strength and hardness. It is typically not tempered between 230 and 370 °C (450 to 700 °F) to avoid blue brittleness.
  • Spheroidizing: Heat to 760-775 °C (1400-1425 °F), hold 4-12 hours, then cool slowly.
  • Utwardzanie powierzchniowe: Widely used for electron beam hardening, nitriding (double-stage and single-stage), and induction hardening. It exhibits the best nitriding characteristics among chromium-containing low-alloy steels due to its higher chromium content and nickel-free composition.

Aplikacje

D2 steel is suitable for applications requiring long-term production, high wear resistance, and dimensional stability. Typical applications include cutting and stamping tools and dies, punching dies and tools, forging operations, and trimming tools.

4140 steel is a versatile engineering steel suitable for components requiring moderate hardenability and good strength and toughness. Major applications include drive shafts, shafts for high-load automotive components, gears in critical applications, and high-load components in automotive engines.

Streszczenie

D2 steel is used in applications that require wear resistance and dimensional stability. 4140 steel is a general-purpose alloy steel that provides a good balance of strength and toughness for structural and mechanical components. As a high-performance tool steel, D2 steel has a complex alloy composition, so it is typically more expensive than common 4140 alloy steel.