What temperature is needed for alloy steel forging?

Key Points About Forging Temperatures for Alloy Steel Forgings

1. The temperature range varies widely, depending on the alloy's performance.
Low-alloy steel: Forging temperatures are relatively high (similar to carbon steel), but strict temperature control is required to prevent overheating.
High-alloy steel (such as high-chromium and nickel-based alloys): The forging temperature window is much narrower. A slight increase will result in burnout, while a slight decrease will cause cracking—manipulation is like walking a tightrope.

2. "Fire-through" is essential. 
The billet must reach the target temperature uniformly throughout (commonly known as "burn-through"), otherwise the core will tear during forging.
Large forgings heat more slowly, requiring a stepwise ramp-up and holding. Avoid rapid heating!

3. High-temperature Forbidden Zones: Overheating and Overburning
Overheating (high temperatures): Grain growth becomes excessive, and the forging becomes a "breaded carrot"—strength and toughness plummet.
Overburning (severely exceeding the specified temperature): Grain boundaries melt, resulting in shattering with a single blow (instantly scrapped). Experience-based judgment: Observe the steel's flame color in the furnace (bright yellow to orange-red is safe), using an infrared thermometer.

4. Low-Temperature Red Line: Stop-Forging Temperature
The temperature inevitably drops during forging, and the hammer must be stopped if it falls below a critical value (even if no shape has been formed).
Consequences of too low a stop-forging temperature:
The material becomes "stubborn" (its resistance to deformation increases dramatically), making it prone to cracking during strong forging.
Residual stresses are induced, creating a potential for cracking.
High-alloy steels are particularly sensitive (for example, the stop-forging temperature of high-speed steel requires precise control).

5. Special Alloy Characteristics
Austenitic stainless steel (such as 304): Avoid prolonged exposure to carbide precipitation (around 800°C), as this will negatively impact corrosion resistance.
High-speed tool steel: Requires multiple staged heating to prevent uneven microstructure.
Titanium/Vanadium-containing alloys: Prone to oxidation at high temperatures, requiring a protective atmosphere furnace.

6. Cooling: The source of subsequent potential risks
Absolutely avoid air cooling after forging! High-carbon, high-alloy steels, in particular, will crack if cooled too quickly. Key Operations:
Enter a slow cooling pit (bury with sand/asbestos for insulation).
Or directly enter the furnace for subsequent cooling (stress relief).