Cr12 tool Steel

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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)

C	Cr	Si	Mn	P	S
2.00 – 2.30	11.50 – 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

Položka	Heating Temperature/°C	Initial Forging Temperature/°C	Final Forging Temperature/°C	Způsob chlazení
Ocelový ingot	1140 ~ 1160	1100 ~ 1120	900 ~ 920	Pomalé chlazení
Ocelový předvalek	1120 ~ 1140	1080 ~ 1100	880 ~ 920	Pomalé chlazení

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. Tepelné zpracování

4.1 Předehřívání

	Procesní parametry
General Annealing after Forging	Heating 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.
Izotermické žíhání po kování	Heating 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 Kalení

4.2.1 Quenching Specification

Proces	Quenching Temperature/°C	Způsob chlazení	Tvrdost HRC
Recommended Quenching Specification	950 ~ 980	Chlazení oleje	≥60
Isothermal Quenching Process	Heat 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

Proces tepelného zpracování	Tvrdost HRC	Impact Toughness aᴋ / (J/cm²)	Zadržený austenit (objemová frakce, %)	Tapping Plate Life / x10⁴ pieces	Wear Loss/mg
980°C heating, oil quenching	66.5	14.1	13.2	4	—
980°C heating, 180°C graded quenching 50min	65.8	15.8	—	5	—
980°C heating, 270°C isothermal 3h	62.5	15.9	—	6	11.9
980°C heating, 270°C isothermal 4h	60	17.7	15.02	—	—
980°C heating, 270°C isothermal 5h	59	16.8	—	—	—
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 1h	64.6	14.6	—	12 ~ 15	8.2
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 2h	46.2	14.9	18.31	12 ~ 28	—
980°C heating, 180°C pre-quenching 35min, 270°C isothermal 3h	63.8	15.2	—	—	—

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

4.2.3 Relationship between Quenching Temperature and Hardness

Quenching Temperature/°C	875	900	925	950	975	1000	1050	1100
Tvrdost HRC	54.5	57	60	62.5	65	66	64	59.5

4.3 Temperování

Tempering Specification

Účel temperování	Heating Temperature/°C	Tempering Time (h)	Počet chvění	Tvrdost HRC
Uvolněte stres, stabilizujte strukturu	180 ~ 200	2	1	60 ~ 62
Uvolněte stres, snižte tvrdost	320 ~ 350	2	1	57 ~ 58

Poznámka: 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/°C	Není temperovaný	200	300	400	450	500	550	600	650
Tvrdost HRC	65	63	62	60	60	60	59.5	57.1	44

Poznámka: 955°C oil quenching.

5. Aplikace

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
Měřidla
Údery
Thread rolling plates and dies
Stamping and punching dies
Tažírna drátu
Vytlačování za studena umírá
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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