Introduction

EN353 is a high-quality, case-hardening (carburizing) alloy steel known for its excellent wear resistance, toughness, and fatigue strength. It is widely used for components requiring high surface hardness combined with a tough core to withstand heavy loading and impact. EN353 offers good mechanical properties after case hardening and is suitable for a wide range of industrial applications, particularly in automotive and mechanical engineering sectors.

Properties of the Grade:

  • Excellent surface hardness after carburizing
  • High core toughness and strength
  • Good fatigue and wear resistance
  • Good dimensional stability during heat treatment
  • Suitable for precision case-hardening applications
  • Good machinability in annealed condition
  • Moderate corrosion resistance with protective treatment

Uses/Applications of the Grade:

EN353 is used extensively in:

  • Gears and shafts
  • Heavy-duty automotive components
  • Worm gears and pinions
  • Camshafts
  • Transmission parts
  • Crankshafts
  • Machine tool spindles
  • Bushings and bearings
  • Couplings

Chemical Composition:

Element Content (%)
Carbon (C) 0.17 – 0.23
Silicon (Si) 0.10 – 0.35
Manganese (Mn) 0.50 – 0.80
Chromium (Cr) 0.90 – 1.20
Nickel (Ni) 1.10 – 1.40
Molybdenum (Mo) 0.08 – 0.15
Sulfur (S) ≤ 0.035
Phosphorus (P) ≤ 0.035

Mechanical Properties:

(After Case Hardening and Tempering)

Property Typical Value
Tensile Strength 850 – 1000 MPa
Yield Strength ≥ 650 MPa
Elongation ≥ 12%
Impact Value (Izod) ≥ 54 J
Surface Hardness (after Carburizing) 58–62 HRC
Core Hardness 28–40 HRC

Physical Properties:

Property Typical Value
Density 7.85 g/cm³
Modulus of Elasticity 210 GPa
Thermal Conductivity ~ 45 W/m·K
Specific Heat Capacity ~ 460 J/kg·K
Coefficient of Thermal Expansion ~ 11 × 10⁻⁶ /°C

Forging:

Procedure:

  • Forging Temperature Range: 850°C – 1150°C
  • Preheat slowly to 850°C.
  • Forge at 1050°C – 1150°C.
  • Cool slowly in furnace or dry ash after forging to avoid cracking.

Heat Treatment:

  1. Annealing:
    1. Heat to 830°C – 860°C.
    2. Hold and then cool slowly in the furnace.
    3. Produces a soft structure for improved machinability.
  2. Case Hardening (Carburizing):
    1. Carburize at 880°C – 920°C.
    2. Cool slowly or quench depending on process.
  3. Hardening:
    1. Reheat to 780°C – 820°C after carburizing.
    2. Quench in oil.
  4. Tempering:
    1. Temper immediately after hardening at 150°C – 200°C.
    2. Air cool.
    3. Achieves the desired surface hardness and toughness balance.

Dimensional Tolerances:

  • Hot Rolled Bars: Tolerances as per EN 10060.
  • Bright Bars (Drawn or Peeled): Tolerances as per ISO h9 or h11.
  • Ground Bars: Precision tolerances up to h6 standard

Machinability:

  • Good machinability in the annealed condition.
  • Use high-speed steel or carbide tools for efficient machining.
  • Adequate lubrication/cooling is recommended for prolonged tool life and excellent surface finish.

Corrosion Resistance:

  • Moderate corrosion resistance in untreated condition.
  • Application of protective coatings (like phosphating, oiling) or surface treatments (like plating) is advised for corrosive environments.

Weldability:

  • Fair weldability with proper procedures.
  • Preheating to 200°C – 300°C before welding is recommended.
  • Post-weld stress-relieving is advisable to prevent cracking and distortion.
  • Low hydrogen welding electrodes should be used.

Available Form:

EN353 is available in:

  • Hot Rolled Bars
  • Bright Bars
  • Peeled and Turned Bars
  • Forged Bars
  • Precision Ground Bars
  • Custom cut-to-size pieces

Supplied in various heat-treated conditions such as annealed, normalized, or quenched and tempered depending on customer requirements.

Conclusion:

EN353 Alloy Steel Bar is an outstanding choice for case-hardening applications where excellent surface wear resistance coupled with a strong and tough core is required. Its balanced chemical composition, ease of machining, and superb heat treatment response make it highly preferred in the automotive, mechanical engineering, and tooling industries. Proper processing ensures long service life even under heavy mechanical stress conditions.

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