SAE 4130 alloy steel

Introduction

We manufacture forging ingots, billets, and blooms in alloy steel specifically for SAE 4130, designed for moderate-to-high strength engineering applications where good toughness and weldability are required. SAE 4130 is a low carbon chromium-molybdenum alloy steel known for its excellent strength-to-weight ratio, good toughness, and superior weldability compared to higher carbon grades. It is widely used in structural, automotive, and aerospace applications. The addition of chromium enhances hardenability and wear resistance, while molybdenum improves toughness, fatigue resistance, and stability during heat treatment. Due to its lower carbon content, SAE 4130 offers excellent formability and machinability in the annealed or normalized condition. SAE 4130 provides a reliable balance of strength, toughness, fabrication ease, and cost-effectiveness for light to medium-duty engineering applications.

Chemical composition

Element Content (%) Function / effect
Carbon (c) 0.28 – 0.33 Provides basic strength and hardenability
Manganese (mn) 0.40 – 0.60 Improves toughness and hardenability
Silicon (si) 0.15 – 0.35 Increases strength and elasticity
Chromium (cr) 0.80 – 1.10 Enhances hardenability and wear resistance
Molybdenum (mo) 0.15 – 0.25 Improves toughness and fatigue resistance
Phosphorus (p) Max 0.035 Impurity; controlled to maintain toughness
Sulphur (s) Max 0.040 Impurity; controlled for machinability

Mechanical properties (typical – quenched & tempered)

  • Tensile strength: 560 – 850 MPa
  • Yield strength: 460 – 700 MPa
  • Hardness: 18 – 28 HRC
  • Impact toughness: Good
  • Fatigue resistance: Good

(Properties may vary depending on section size and heat treatment conditions)

Heat treatment

  • annealing: used to improve machinability and soften the material for forming operations.
  • normalizing: enhances uniformity of microstructure and improves mechanical properties.
  • quenching: heating to approximately 830 – 860°c followed by oil quenching to achieve increased strength.
  • tempering: performed to relieve internal stresses and improve toughness while maintaining required strength.Heat treatment parameters can be adjusted based on application requirements.

Key features and benefits

  • good strength-to-weight ratio
  • excellent weldability compared to higher carbon grades
  • good toughness and fatigue resistance
  • easy formability and machinability
  • dimensional stability after heat treatment
  • cost-effective for structural and engineering uses

Typical applications

  • aircraft structures and tubing
  • automotive chassis and suspension parts
  • structural tubes and pipes
  • gears, shafts, and fasteners
  • bicycle frames and roll cages
  • general engineering and fabricated components

Equivalent steel grades

  • SAE 4130 has several international equivalents, including:
  • en 25CrM04 – european standard
  • din 25CrM04 – german standard
  • is 1570 (part 3) – 25CrM04 type – indian standard

Why choose SAE 4130 for your application?

SAE 4130 is an excellent choice where a combination of moderate strength, good toughness, and easy fabrication is required. Its superior weldability and formability make it ideal for structural and tubular applications, while its response to heat treatment ensures reliable performance and long service life.

Comparison table for similar grades

Grade Carbon (%) Key applications Heat treatment Comments
SAE 4130 0.28 – 0.33 Structural tubes, aircraft parts Normalizing / quench & temper Excellent weldability
SAE 4140 0.38 – 0.43 Gears, shafts, crankshafts Quenching & tempering Higher strength
25CrM04 0.22 – 0.29 Structural and automotive parts Normalizing / q&t European equivalent

Summary

SAE 4130 is a versatile chromium-molybdenum alloy steel that offers a balanced combination of strength, toughness, and fabrication ease. It is widely used in automotive, aerospace, and general engineering applications where reliable performance and cost-effectiveness are essential.