Does H13 steel need tempering after quenching?

After quenching, H13 steel needs to be tempered. It is impossible to skip this important stage of the tempering process. Tempering successfully removes the internal stress produced during quenching, keeps the workpiece from cracking, stabilizes the dimensions and microstructure, and guaranties that the hardness is within the 48–52 HRC service range.

 

1. What makes tempering essential?

Removing residual stress: After quenching, the workpiece has a high residual stress that, if applied directly, might easily cause deformation or cracking.

Microstructure stabilization: Toughness and dimensional stability are enhanced by converting unstable quenched martensite into tempered martensite.

Hardness adjustment: lowering the hardness to the safe service range of 48–52 HRC from the high level upon quenching (possibly >55 HRC).

Enhancing overall performance: Meeting mold steel's service requirements by increasing toughness without sacrificing high strength.

Process specifications: Following quenching, H13 steel is typically put through two high-temperature tempering operations (550–600°C), each of which is held at that temperature for longer than two hours.

 

2. Key Points of the Tempering Process

Parameter of the Item

Controlling the Temperature

550–600°C (modify slightly according on the desired hardness)

Tempering Periods

At least twice (to avoid rebounding residual tension).

Cooling Technique

Cooling with air (to prevent secondary stress)

Supporting Conditions

requires hardness test results and furnace temperature curve data.

For instance, a Wuhan business achieved a final hardness of 49.5 HRC by performing 580℃×2h×2 tempering cycles on H13 hot runner nozzles following quenching.

 

3. Dangers of Not Tempering

High risk of cracking: The workpiece is vulnerable to abrupt fracture during production or usage because residual stress is not dissipated;

Dimensional instability: Mold accuracy is impacted by micro-deformation that happens during service;

Poor toughness: Quenched martensite is fragile, easily chipped or broken, and has poor impact resistance;

Criteria for Disqualification: Any H13 workpiece that hasn't been tempered is deemed a semi-finished product and isn't allowed to be used. "Quenching must be tempered, and tempering must be done at least twice" is a safety principle that guaranties dependable performance and safety.\