High-Carbon, High-Chromium Cr12 Cold-Work Die Steel

Cr12 is a high-carbon, high-chromium cold-work die steel containing over 2% carbon and 11–13% chromium; it is a classic material for cold-stamping dies, cold-heading dies, and shearing tools.
 
Characterized by a high carbide content (approximately 15–20%) and excellent wear resistance, Cr12 can achieve a hardness of 60–64 HRC after quenching. It is widely used in the cold-work die industry, with Cr12MoV and Cr12Mo1V1 (D2) serving as its improved variants.
 
The high carbon and chromium content imparts exceptional wear resistance and compressive strength to Cr12. Cutting edges in blanking dies must withstand wear, while deep-drawing dies must resist adhesive wear; the hard carbide phases in Cr12 enable it to perform outstandingly in these applications. However, this high carbide content also presents drawbacks—specifically, poor toughness and severe carbide segregation—which are the critical issues requiring process control when working with Cr12.
 
Cr12 is typically supplied in the annealed state (hardness: 207–255 HB), with carbide non-uniformity inspected against standards at the time of delivery. Carbide segregation is more severe in large-dimension materials than in smaller ones; therefore, forgings or re-forged stock should be selected for critical dies, and the directionality of carbide distribution in rolled plate must also be taken into account.
 
Heat treatment parameters: Quench at 950–980°C followed by oil quenching or air cooling (the quenching temperature for Cr12 is lower than that for Cr12MoV); temper at 180–200°C (low-temperature tempering) to achieve high hardness, or at 400–500°C to obtain a balance between toughness and wear resistance. Cr12 exhibits good hardenability—hardening can be achieved even via air cooling—and undergoes minimal deformation.
 
Controlling Quenching Deformation in Cr12: Due to carbide directionality and quenching stresses, Cr12 molds exhibit complex deformation patterns after quenching; machining allowances should be determined based on empirical data. For precision molds, consider using Cr12MoV or Cr12Mo1V1 (which offer lower deformation) or employing vacuum heat treatment to minimize distortion.
 
Differences between Cr12 and Cr12MoV: Cr12MoV contains added molybdenum and vanadium, resulting in finer carbides and superior hardenability and toughness, making it suitable for large molds; Cr12 is the standard grade—lower in cost—and is suitable for small-to-medium molds and wear-resistant parts. D2 (Cr12Mo1V1) represents a further optimization and serves as the internationally recognized upgraded version of the Cr12 series.
 
Cr12 Application Scenarios: Blanking dies, punching dies, bending dies, cold heading dies, deep-drawing dies, gauges, and shear blades.