Cr12 tool Steel

AOBO STEEL – Trusted Global Tool Steel Supplier

Cr12 tool steel is a grade under the Chinese national standard. It is a very classic high-carbon, high-chromium cold work die steel that combines high strength, wear resistance, and hardenability. Equivalent grades to Cr12 include American AISI D3, German W – Nr. 1. 2080, and Japanese JIS SKD1.

1. Composition(GB / T 1299—2000)

CCrSiMnPS
2.00 – 2.3011.50 – 13.00≤ 0,40≤ 0,40≤ 0.030≤ 0.030

2. Mechanical Properties

Cr12 steel is classified as a high-carbon, high-chromium ledeburitic steel. Due to its high mass fraction of carbon, it exhibits lower impact toughness and a tendency for brittle fracture, coupled with a susceptibility to forming non-uniform eutectic carbides.

The high concentration of chromium in the steel promotes the formation of (CrFe)₇C₃ complex carbides, which in turn reduces the amount of cementite (Fe₃C). During the quenching heat treatment, a significant volume of these carbides dissolves into the austenite phase. Subsequent quenching transforms the austenite into high-hardness martensite. Upon tempering, a fine and dispersed precipitation of carbides occurs within the martensitic matrix, resulting in excellent wear resistance.

Through an appropriate heat treatment process, a microstructure with a combination of high strength and toughness can be achieved.

3. Forging Process

ÖğeHeating Temperature/°CInitial Forging Temperature/°CFinal Forging Temperature/°CSoğutma Yöntemi
Çelik Külçe1140 ~ 11601100 ~ 1120900 ~ 920Yavaş Soğutma
Çelik Kütük1120 ~ 11401080 ~ 1100880 ~ 920Yavaş Soğutma

The primary objective of forging Cr12 steel is to break down and refine the coarse carbides inherent in the steel, ensuring they are distributed uniformly throughout the matrix. This process significantly improves the material’s overall strength and toughness. Furthermore, proper forging establishes a rational alignment of flow lines within the die, which helps to promote consistent and predictable dimensional changes (distortion) in all directions during the subsequent quenching process.

Regarding the heating procedure for forging, it is crucial to first preheat the workpiece before gradually increasing it to the final forging temperature. Attention must be paid to the proper placement of the workpiece within the furnace, and the material should be turned or flipped periodically to ensure uniform heating.

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4. Isıl İşlem

4.1 Ön ısıtma

İşlem Parametreleri
General Annealing after ForgingHeating temperature: 850 ~ 870 °C. After uniform heating, hold for 4 ~ 5h. Furnace cool at a rate of <30°C/h to below 500°C, then air cool. Hardness after annealing: ≤229HBW. Microstructure after annealing: granular pearlite + carbide.
Dövme Sonrası İzotermal TavlamaHeating temperature: 830 ~ 850 °C. Hold for 2 ~ 3h. Furnace cool to 720 ~ 740°C and hold for 3 ~ 4h. Furnace cool to below 550°C, then air cool. Hardness after annealing: ≤269HBW. Microstructure: granular pearlite + carbide.

4.2 Söndürme

4.2.1 Quenching Specification

SüreçQuenching Temperature/°CSoğutma YöntemiSertlik HRC
Recommended Quenching Specification950 ~ 980Yağ Soğutma≥60
Isothermal Quenching ProcessHeat to 980°C, hold for a certain period, then isothermally hold in a salt bath at 250 ~ 280°C for a period of time, and then air cool to obtain a mixed structure of lower bainite + martensite + retained austenite + carbide. Then, temper at an appropriate temperature to obtain a high-toughness structure.

4.2.2 Performance Comparison of Different Heat Treatment Processes

Isıl İşlem ProsesiSertlik HRCImpact Toughness aᴋ / (J/cm²)Tutulan Austenit (Hacim Oranı, %)Tapping Plate Life / x10⁴ piecesWear Loss/mg
980°C heating, oil quenching66.514.113.24
980°C heating, 180°C graded quenching 50min65.815.85
980°C heating, 270°C isothermal 3h62.515.9611.9
980°C heating, 270°C isothermal 4h6017.715.02
980°C heating, 270°C isothermal 5h5916.8
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 1h64.614.612 ~ 158.2
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 2h46.214.918.3112 ~ 28
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 3h63.815.2

Note: All samples were tempered twice at 180°C, 1.5h each time.

4.2.3 Relationship between Quenching Temperature and Hardness

Quenching Temperature/°C875900925950975100010501100
Sertlik HRC54.5576062.565666459.5

4.3 Temperleme

Tempering Specification

Temperlemenin AmacıHeating Temperature/°CTempering Time (h)Öfke SayısıSertlik HRC
Stresi azaltın, yapıyı dengeleyin180 ~ 2002160 ~ 62
Stresi azaltın, sertliği azaltın320 ~ 3502157 ~ 58

Not: The tempering temperature is generally 180 ~ 200°C, with hardness ≥60HRC. To avoid cracks from EDM and grinding and to improve the toughness of the mold, it is often tempered below 400°C. The hardness after tempering is 54 ~ 58HRC. The temper brittleness range is 275 ~ 375°C, which should be avoided as much as possible during tempering.

Relationship between Tempering Temperature and Hardness

Tempering Temperature/°CSertleştirilmemiş200300400450500550600650
Sertlik HRC65636260606059.557.144

Not: 955°C oil quenching.

5. Uygulamalar

It is predominantly selected for manufacturing components that require high wear resistance but are subjected to relatively low impact loads.

Specific applications include:

  • Cold shearing blades and cutters
  • Drill bushings
  • Ölçerler
  • Yumruklar
  • Thread rolling plates and dies
  • Stamping and punching dies
  • Tel çekme kalıpları
  • Soğuk ekstrüzyon kalıpları
  • Coining and embossing dies
  • Deep drawing dies

Your Premier Source for Cr12 Round Bars and Plates

Leverage our 20+ years of expertise. We supply high-quality Cr12 tool steel in both round bars and plates, perfect for applications requiring high wear resistance and compressive strength. Contact our specialists for detailed specifications and a competitive quote.

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