Hot-rolled plate 45# (i.e., No. 45 steel) detailed information, compiled from multiple authoritative sources:

1. Basic Material Information

• Chemical Composition:
  Carbon content 0.42%-0.5%, manganese 0.5%-0.8%, silicon 0.17%-0.37%, sulfur and phosphorus ≤0.035%14.
• Mechanical Properties:
  • Tensile strength ≥600MPa, yield strength ≥355MPa, elongation ≥16%1.
  • Hardness can reach above HRC55 after heat treatment15.
• International Designations:
  Japan S45C, USA 1045, Germany C4514.

• 2. Application Fields

  • Mechanical Manufacturing: Gears, shafts, connecting rods, and other high-strength components15.
  • Construction Structures: Reinforcing bars, load-bearing components1.
  • Industrial Equipment: Pressure vessels, pipelines, and other pressure-resistant components5.

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  3. Heat Treatment and Processing

  • Heat Treatment Processes:
    • Quenching and tempering can improve overall performance5.
    • Carburizing treatment can enhance surface wear resistance2.
  • Processing Recommendations:
    • Annealing is required after welding to reduce internal stress2.
    • Good cold stamping performance, suitable for sheet metal parts24.
    • As a high-quality carbon structural steel, No. 45 steel is widely used in multiple industrial fields due to its excellent mechanical properties and processing adaptability. The following is a detailed classification of its main application areas:

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      1. Mechanical Manufacturing Field

      • Shaft Parts: Key components such as transmission shafts, machine tool spindles, and crankshafts, utilizing their high strength and wear resistance13.
      • Gears and Transmission Parts: Gears, racks, sprockets, etc., suitable for medium loads and low-speed scenarios316.
      • Mold Components: Mold bases, ejector pin guide sleeves, etc., with surface hardness (HRC52-58) improved through quenching and tempering or high-frequency quenching1619.

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      2. Automotive Industry

      • Chassis and Frames: Load-bearing structural parts such as automobile beams and cross members212.
      • Engine Components: Connecting rods, crankshafts, etc., which need to withstand high loads and impacts1119.
      • Transmission Systems: Transmission gears, drive shafts, etc.1316.

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      3. Construction and Engineering

      • Bridges and High-Rise Buildings: Used as load-bearing components or support structures, such as steel beams and pile foundations1112.
      • Formwork and Scaffolding: Utilizing their weldability and deformation resistance1112.

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      4. Petrochemical and Energy

      • Pressure Vessels and Pipelines: Used in oil and gas transportation equipment after anti-corrosion treatment511.
      • Energy Equipment: Wind turbine components, solar brackets, etc.1314.

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      5. Other Fields

      • Shipbuilding: Hull structural parts and mechanical components1214.
      • Agricultural Machinery: Wear-resistant parts such as plow blades and drive shafts1519.
      • Medical Devices: Base materials for some surgical instruments911.