Hardening Furnace Temperature Guide for Tool Steel and Alloy Steel

Accurate temperature control is the core of qualified hardening processing for tool steel and alloy steel. Tool steel and alloy steel are high-performance special steel materials with complex chemical composition and strict phase transformation requirements. Unreasonable hardening furnace temperature will lead to insufficient hardening, excessive brittleness, grain coarsening and workpiece cracking, directly resulting in unqualified product performance. This guide sorts out standardized hardening temperature parameters for mainstream tool steel and alloy steel to support factory standardized production.

1. Carbon Tool Steel Hardening Temperature Parameters

Common carbon tool steel including T7, T8, T10 and T12 has a standard hardening temperature range of 760–810°C. These steels have high carbon content and good hardenability, requiring low to medium temperature hardening. Excessively high temperature will cause grain coarsening and increased brittleness, making tools prone to cracking during use; low temperature leads to insufficient phase transformation and unqualified hardness. Thin tool parts adopt 760–780°C low-temperature hardening, while thick heavy-duty tools use 790–810°C appropriately to ensure thorough hardening.

2. Alloy Tool Steel Hardening Temperature Parameters

Low-alloy tool steel (CrWMn, 9CrSi) adapts to 790–830°C hardening temperature. Alloy elements refine grains and improve hardenability, enabling uniform hardening at medium temperature, suitable for precision measuring tools and small molds. High-alloy mold steel (Cr12, Cr12MoV) requires high-temperature hardening at 1000–1050°C to fully dissolve alloy carbides, eliminate internal structural defects and obtain high hardness and wear resistance after hardening.

3. High-Speed Tool Steel Hardening Temperature Parameters

High-speed steel (W18Cr4V, M2) for high-speed cutting tools has ultra-high hardening temperature of 1180–1230°C. Only ultra-high temperature heating can complete full phase transformation of high-alloy components, obtain excellent red hardness and cutting performance, and ensure that tools maintain stable hardness and wear resistance under high-temperature cutting conditions.

4. Structural Alloy Steel Hardening Temperature Parameters

Low-alloy structural steel (40Cr, 35CrMo, 20CrMnTi) widely used in machinery has a hardening temperature of 820–870°C. This temperature range balances hardness and toughness, making it suitable for hardening of gears, shafts and structural parts. High-strength alloy steel for engineering machinery adopts 850–900°C hardening temperature to maximize material strength and impact resistance.

Production Parameter Adjustment Rules

In actual hardening processing, temperature parameters need to be fine-tuned according to workpiece thickness and process requirements. Thick workpieces need toIn actual hardening processing, temperature parameters need to be fine-tuned according to workpiece thickness and process requirements. Thick workpieces need to appropriately increase the hardening temperature by 20–40°C and extend soaking time to ensure full phase transformation of the workpiece core and avoid insufficient internal hardening. Thin and precision workpieces should adopt the lower limit of the standard temperature range to prevent overheating grain coarsening and micro-deformation, maintaining dimensional accuracy while meeting hardness standards.

In addition, combined with different hardening furnace types, parameter adjustment is required. Continuous mesh belt hardening furnaces with fast heating speed can adopt the middle and lower limit of the temperature range; batch box-type hardening furnaces with slow and uniform heating can appropriately use the upper limit temperature to ensure thorough hardening. Matching with reasonable soaking time and cooling mode, it can effectively avoid common defects such as unqualified hardness, brittle failure and workpiece deformation, and greatly improve the yield of tool steel and alloy steel hardening processing.

Standardized temperature parameter setting is the core premise of high-quality hardening processing. Modern intelligent hardening furnaces can store exclusive parameter curves for various tool steels and alloy steels, realizing one-click accurate heating and stable batch processing quality, which is widely recognized in precision mold, tool manufacturing and mechanical parts processing industries.