D2 steel Vs. 4140: What are the difference?

D2 steel Vs. 4140: فولاذ الأدوات D2 و فولاذ 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.

تعبير

العنصر	D2 Tool Steel (%)	4140 Steel (%)
الكربون (C)	1.40 – 1.60	0.38 – 0.43
الكروم (Cr)	11.00 – 13.00	0.80 – 1.10
الموليبدينوم (Mo)	0.70 – 1.20	0.15 – 0.25
المنجنيز (Mn)	0.10 – 0.60	0.75 – 1.00
الفاناديوم (V)	0.50 – 1.10	–
السيليكون (Si)	0.10 – 0.60	0.15 – 0.35
الفوسفور (P)	≤ 0.03	≤ 0.035
الكبريت (S)	≤ 0.03	≤ 0.040

الخصائص الميكانيكية

1. صلابة. صلابة الفولاذ 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. قابلية التصلب. 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. الصلابة. 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. مقاومة التآكل. يتمتع الفولاذ D2 بخصائص عالية للغاية يرتدي 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. قابلية التصنيع. 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. ثبات الأبعاد. 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.

المعالجة الحرارية

• Heat Treat D2 Steel:
  • التلدين: Proper annealing is crucial for machinability.
  • التصلب: Typically air-hardened. Austenitizing temperatures range from 980 to 1025 °C (1800 to 1875 °F).
  • التلطيف: Generally double-tempered. Tempering at low temperatures (e.g., 200 °C) can achieve maximum hardness.
  • معالجة السطح: Can be ion nitrided to significantly increase surface hardness and wear resistance.
• 4140 Steel:
  • التطبيع: Heat to 845-925 °C (1550-1700 °F) and air cool.
  • التلدين: Heat to 830-870 °C (1525-1600 °F) and cool slowly in the furnace.
  • الإطفاء: 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.
  • التلطيف: 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.
  • تصلب السطح: 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.

التطبيقات

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.

ملخص

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.