Gb Cr12 Steel Bar Spheroidizing Annealing Softening Treatment - China

GB Cr12 steel is a widely used high-carbon, high-chromium cold work die steel in the Chinese national standard (GB/T 1299).

It possesses excellent wear resistance, high hardness, and good hardenability, making it an ideal material for manufacturing precision tools such as cold stamping dies, cold shearing tools, and deep drawing dies.

However, Cr12 steel has a high hardness in its supplied state, making direct machining difficult.

Therefore, **spheroidizing annealing softening treatment** becomes an indispensable key link in its heat treatment process chain.

This article will analyze in depth the core technical points, process parameters, and common solutions for the spheroidizing annealing softening treatment of GB Cr12 steel.

GB Cr12 steel bar spheroidizing annealing process specification According to GB/T 1299 standard and industry practice, the following process parameters are recommended for spheroidizing annealing of GB Cr12 steel bars: | Process Stage | Temperature Parameter | Time Parameter | Cooling Method | Target Hardness | |||||| | **Heating and Holding** | 850~870°C | 2~4 hours | — | — | | **Furnace Cooling Stage** | Cooling rate of 30°C/h to | — | Furnace Cooling | — | | **Isothermal Transformation** | 730~750°C | 4~6 hours | Furnace Cooling | — | | **Final Cooling Stage** | 500~600°C | — | Air Cooling after Furnace | 217~269 HBW | **Key Process Points Analysis: ** - **Heating Temperature Control: ** 850~870°C, above Ac1 (approximately 800°C) and below Accm, ensuring the transformation of pearlite to austenite in the original microstructure while avoiding excessive carbide dissolution.

**Isothermal Temperature Selection: ** 730~750°C, slightly higher than Ar1 (approximately 760°C), promoting the transformation of austenite to spheroidal pearlite.

**Cooling Rate Control: ** Furnace cooling rate ≤30°C/h.

Excessive cooling will cause hardness to rebound, while excessive cooling will reduce production efficiency.

Company Contact:

• Posted By: Dongguan Songshun Mould Steel Co., Ltd.

• Phone: 076985475596

• Address: 1st Floor, No. 1, Dongda Fourth Street, Shatou Community, Chang'an Town, Dongguan , Guangdong , China

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• Business Description: Established in 2009,Songshun Steel supplies a wide range of carbon, alloy and tool steel products, including high speed tool steel, cold work tool steel, hot work tool steel, plastic mould steel, engineering steel and machine structural steel etc.
  
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