Q345R is a low-alloy steel specifically engineered for pressure vessel applications under GB/T 713 standards. Delivered in hot-rolled or normalized states, it combines exceptional strength (tensile ≤540 MPa) with enhanced weldability, making it ideal for boilers, heat exchangers, and multilayer container fabrication.

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Applications

Core Industrial Uses:

Multilayer pressure vessels
Thick-walled components

• Shells (>36 mm)
• Tube sheets & flanges
• End caps (>50 mm requiring normalization)
  Critical infrastructure:
• LNG storage tanks
• Nuclear reactor auxiliary systems

Mechanical Property

Mechanical Property of Q345R

Chemcial Composition

Chemical Composition of Q345R

Welding Guidelines

Pre- & Post-Weld Protocols:

1. Preheating:
   • ≤34 mm thickness: Not required
   • >34 mm: Preheat to 100–150°C
2. Heat Treatment:
   • Mandatory stress relief at 600–640°C for normalized plates >34 mm
   • Cooling method: Air-cool to 400°C, then furnace-cool
3. Energy Control:
   • Low-carbon plates: Small linear energy (prevents grain coarsening)
   • High-carbon plates: Larger linear energy (reduces martensite-induced brittleness)

Quality Assurance

Non-Destructive Testing (NDT):

• Ultrasonic Testing (UT) Requirements:
  • 30–36 mm: Grade III (partial zones)
  • >36 mm: Grade II (full coverage)
  • >80 mm: Enhanced UT per design specs

Documentation:

• Mandatory Certificates:
  • Mill Test Certificate (MTC) with actual yield/tensile ratios
  • Heat treatment records
  • Impact toughness reports (Charpy V-notch)

Why Choose Q345R?

• Cost-Efficiency: 15–20% weight reduction vs. conventional steels
• Safety Compliance: Meets hydrogen-induced cracking (HIC) resistance standards
• Versatility: Adaptable to ASME SA516 Gr70 equivalency