The differences are mainly reflected in quality grade, production process, performance characteristics, and application scenarios, with specific comparisons as follows:

1. Q390C Steel Plate

• Quality Grade: Grade C (requiring impact toughness at room temperature)
• Production Process: Can be produced by hot rolling, normalizing, or thermomechanical controlled processing (TMCP)
• Core Characteristics:
  • Mechanical Properties: Yield strength ≥390MPa, tensile strength 490–650MPa, impact energy at room temperature ≥34J
  • Composition Features: Contains microalloying elements (niobium, vanadium, titanium), carbon equivalent ≤0.45%, good weldability
• Typical Applications:
  • Building steel structures, engineering machinery (crane booms, excavator chassis)
  • Heavy-duty structural components for conventional temperature environments (above 0°C)

2. Q390NC Steel Plate

• Quality Grade: Grade D (requiring low-temperature impact toughness)
• Production Process: Must be normalized or normalized rolled (designation "N")
• Core Characteristics:
  • Low-Temperature Toughness: Impact energy at -20°C ≥34J, suitable for frigid regions
  • Composition Optimization: Addition of niobium (Nb: 0.01–0.05%) and vanadium (V) to refine grains and improve strength-toughness balance
• Typical Applications:
  • Bridges in cold regions, wind power tower sections, low-temperature pressure vessels
  • Heavy equipment requiring high low-temperature crack resistance
    

  • High-strength coil	11.5	Q390C		1500	1	28.4
    High-strength coil	11.5	Q390C		1500	1	28.59
    High-strength coil	7.5	Q390C		1500	1	28.69
    High-strength coil	7.5	Q390C		1500	1	28.76
    High-strength coil	5.5mm	Q390C		1600	1	29.02
    High-strength coil	5.75mm	Q390C		1500	1	28.62
    High-strength coil	11.5	Q390C		1500	1	28.95
    High-strength coil	4.5mm	Q390C		1500	1	28.65