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Why is Cr12MoV Material Generally Supplied Annealed?

Cr12MoV material is almost fully supplied in annealed condition in the mold steel market. The hardness for annealed delivery is normally controlled from 207 to 255 HB. This industry practice is not a random choice. It comes from the combined effect of material properties, machining needs and later heat treatment processes.

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Cr12MoV Material
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Cr12MoV Steel

Performance Reason of Cr12MoV Material

Microstructure Defects of Cr12MoV Steel

Cr12MoV material is Cr12‑series ledeburite cold‑work die steel. It contains eutectic ledeburite structure and network eutectic carbides in as‑cast condition. This structure has extremely high hardness. Carbides account for about 20% in the annealed state. Without annealing treatment, cracks are very likely to occur in subsequent forging and machining.

Excessively High Hardness in Forged Condition

Forged Cr12MoV steel must be annealed. The as‑forged material has high hardness and is hard to machine. Annealing reduces hardness from as‑forged state to 207～255 HB, so the material can be milled, turned or drilled by standard machining operations.

Good Machinability of Cr12MoV Steel

Cutting Performance Improvement of Cr12MoV Material

Annealing reduces steel hardness. It makes cutting of Cr12MoV material much easier. Rough milling can be done with hard cutting tools. The first step of mold making is usually rough shaping of steel. If material hardness is too high, mold processing time will increase greatly, and tool wear cost will rise sharply.

Remove Internal Stress of Cr12MoV Tool Steel 

Structure stress and thermal stress from forging or rolling are removed during annealing. Unannealed Cr12MoV steel may deform or even crack when residual stress is released during storage.

Guarantee Good Microstructure of Cr12MoV Material

Spheroidizing Annealing

Cr12MoV material normally uses isothermal spheroidizing annealing process. Heating temperature is 850～870℃, and isothermal temperature is 720～750℃. After annealing, it gets spheroidized structure of sorbite pearlite plus granular carbides. This structure is the ideal initial structure for later quenching treatment.

Guarantee Uniformity of Quenched Microstructure

The spheroidized structure after annealing provides good structure base for final quenching. Spherical carbides distribute evenly. It helps carbide dissolution and uniform austenite composition during quenching heating. If delivered in as-forged or as-cast state, network carbides can hardly dissolve fully during quenching heating. It easily causes uneven hardness, local soft spots and even quenching cracks after quenching.

Industry Standards and Practices of Cr12MoV Tool Steel

Provisions of National Standard

  1. GB/T 1299 Alloy Tool Steel (the 2025 version is renamed Tool and Die Steel) specifies that Cr12MoV steel shall be delivered in annealed condition. The delivery hardness in annealed state is 207～255 HB. Delivery in normalized, annealed, black skin or quenched and tempered state after rough machining shall be stated in the contract. Annealed delivery is the default standard state.
  2. The current valid versions of this Cr12MoV tool steel standard include GB/T 1299-2014. The latest version GB/T 1299-2025 takes effect on May 1, 2026. It adds grading requirements for carbide non-uniformity of cold-work die steel, and puts forward more specific rules for quality control of annealed microstructure.

Processing Division Practice Between Supplier and Buyer

There is a clear processing division between Cr12MoV steel mills and mold manufacturers. Steel mills complete smelting, forging and annealing, and supply raw materials with proper hardness and qualified microstructure. Mold factories carry out subsequent rough machining, finish machining and final heat treatment.

FAQ of Cr12MoV Material

Q1: Can users machine Cr12MoV material if it is delivered in quenched and tempered condition?

A: No. Quenched and tempered condition (quenching + tempering) usually has hardness ≥58 HRC. It can only be processed by grinding and EDM, and cannot use normal cutting. Molds with complex cavities need annealing before machining.

A: Cutting becomes hard, tool wears fast, and processing time increases. In addition, spheroidization is incomplete. It easily causes uneven hardness or cracks after quenching.

A: Isothermal spheroidizing annealing: heating at 850–870°C, isothermal holding at 720–750°C, then slow cooling. Fast cooling leaves flaky pearlite.

A: High-quality Cr12MoV material accurately controls isothermal spheroidizing annealing parameters to get finer and even spherical carbides. Its hardness can drop below 225 HB. Cutting is smoother and tool life is longer. More even spheroidization brings better hardness uniformity after quenching and lower cracking risk.

A: Residual network carbides are hard to dissolve during quenching heating. Austenite becomes uneven, which leads to uneven hardness, soft spots or even cracks.

A: Test hardness (207–255 HB), check spheroidization grade and carbide network / band structure by metallography, and review material certificate. It is unqualified if hardness exceeds limit or carbide network is serious.

Conclusion

Cr12MoV material is delivered in annealed condition in Keyspark Steel Mostly. Annealing reduces hardness to 207～255 HB for easy cutting and removes internal stress. Spheroidizing annealing provides uniform microstructure for final quenching and lowers cracking risk. GB/T 1299 also sets annealed state as the default delivery condition.

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