1. Annealing
Process: Heating to 650–750°C (below Ac1 critical point), holding, then slow cooling (furnace cooling).
Effects:
Reduces internal stress from rolling/forming, improving dimensional stability during subsequent processing.
Softens the material by reducing hardness, enhancing machinability (useful for complex machining operations).
Limits grain growth, maintaining a fine microstructure to preserve basic strength.
2. Stress Relief Annealing
Process: Heating to 550–650°C, holding, then controlled cooling.
Effects:
Specifically targets residual stresses (e.g., from welding or cold working) without significantly altering the microstructure.
Reduces the risk of post-processing deformation or cracking, critical for structural components like welded frames.
3. Intercritical Annealing (Limited Application)
Process: Heating to a temperature between Ac1 and Ac3 (partial austenitization), then cooling.
Effects:
Can refine ferrite-pearlite structures and adjust carbide distribution.
May slightly improve toughness and formability but is less commonly used than normalization for Q295GNH due to marginal benefits.
1. Annealing
Process: Heating to 650–750°C (below Ac1 critical point), holding, then slow cooling (furnace cooling).
Effects:
Reduces internal stress from rolling/forming, improving dimensional stability during subsequent processing.
Softens the material by reducing hardness, enhancing machinability (useful for complex machining operations).
Limits grain growth, maintaining a fine microstructure to preserve basic strength.
2. Stress Relief Annealing
Process: Heating to 550–650°C, holding, then controlled cooling.
Effects:
Specifically targets residual stresses (e.g., from welding or cold working) without significantly altering the microstructure.
Reduces the risk of post-processing deformation or cracking, critical for structural components like welded frames.
3. Intercritical Annealing (Limited Application)
Process: Heating to a temperature between Ac1 and Ac3 (partial austenitization), then cooling.
Effects:
Can refine ferrite-pearlite structures and adjust carbide distribution.
May slightly improve toughness and formability but is less commonly used than normalization for Q295GNH due to marginal benefits.
