The heat treatment process for Q500NH weathering steel typically involves quenching and tempering (Q&T) to achieve its high strength and balanced toughness. Here's a concise breakdown:
1. Standard Heat Treatment
Quenching:
Heated to 880–950°C, then rapidly cooled (water or oil) to form martensite/bainite for high strength.
Tempering:
Reheated to 550–650°C to reduce brittleness while maintaining yield strength ≥500 MPa.
2. Key Parameters
Microstructure: Tempered sorbite or bainite.
Post-Treatment Properties:
Yield strength: 500–700 MPa
Impact toughness: ≥27J at -20°C (per EN 10025-5).
3. Special Notes
No further patina acceleration: Heat treatment doesn't affect weathering resistance; natural rust stabilization still required.
Welding: Pre/post-heating (150–250°C) may be needed to avoid cold cracking.
