SAE 1078 is a high carbon steel material belonging to the carbon steel series under the standards of the Society of Automotive Engineers (SAE). With its higher carbon content, this material exhibits excellent hardness, strength, and wear resistance, making it widely used in tools, springs, and various high-load mechanical components.

1. Chemical Composition of SAE 1078

• Carbon (C)：0.72–0.85%

• Manganese (Mn)：0.50–0.90%

• Silicon (Si)：0.15–0.37%

• Phosphorus (P)：≤0.035%

• Sulfur (S)：≤0.035%

• Others (Cr, Ni, Cu, etc.)：≤0.25%

Characteristics:

• High carbon steel (C > 0.6%), high hardness but relatively poor plasticity and weldability.

• Does not contain alloying elements (such as Cr, Mo), classified as a plain carbon tool steel.

2. Mechanical Properties of SAE 1078

（1） As Rolled (Unheated State)

• Ultimate Tensile Strength (UTS)：≥1080 MPa

• Yield Strength (YS)：≥880 MPa

• Elongation (%)：≥7%

• Hardness (HB)：≤285 HB

（2）Quenched + Tempered (Hardened State)

• Ultimate Tensile Strength (UTS)：≥780 MPa

• Yield Strength (YS)：≥620 MPa

• Elongation (%)：≥10%

• Impact Toughness (J)：≥27 J

• Hardness (HRC)：40–55 HRC

Note:

• Quenching (820°C±20°C, water cooling) significantly improves hardness (HRC 60+), but increases brittleness.

• Tempering (480°C±50°C) reduces brittleness and balances strength and toughness.

3. Heat Treatment Processes

（1）Annealing (Softening Treatment)

• Temperature: 750–800°C

• Cooling Method: Furnace cooling

• Purpose: Reduce hardness, improve machinability.

（2）Quenching (Hardening Treatment)

• Temperature: 820°C±20°C

• Soaking Time: ≥30 minutes

• Cooling Medium: Water or oil (water quenching is harder but prone to cracking; oil quenching is milder)

• Structure: Martensite (high hardness but brittle).

（3）Tempering (Toughness Adjustment)

• Temperature: 200–500°C (low-temperature tempering for high-hardness tools, high-temperature tempering for springs and elastic parts)

• Soaking Time: ≥1 hour

• Purpose: Reduce quenching stress, improve toughness.

4. Applications of SAE 1078

（1）Tool Manufacturing

• Cutting tools (such as saw blades, chisels)

• Stamping dies (requiring wear resistance)

• Measuring tools (such as calipers, gauges)

（2）Spring Materials

• Barrel springs (high elastic limit)

• Mechanical spring plates

（3）Mechanical Components

• High-wear-resistant gears

• Shaft components (requiring surface hardening)

• High-strength bolts (requiring tempering treatment)

（4）Precision Processing

• Precision rolled strip steel (thickness as low as 0.02mm, tolerance ±5μm)

• High-precision mechanical parts

5. Comparison of SAE 1078 with Other SAE Steels

（1）SAE 1008

• Carbon Content (%)：0.08–0.13

• Main Characteristics：Extremely low carbon, soft and easy to form

• Typical Uses：Stamped parts, welded structures

（2）SAE 1045

• Carbon Content (%)：0.43–0.50

• Main Characteristics：Medium carbon, high strength after tempering

• Typical Uses：Gears, crankshafts, connecting rods

（3）SAE 1078

• Carbon Content (%)：0.72–0.85

• Main Characteristics：High carbon, high hardness and wear resistance

• Typical Uses：Cutting tools, springs, dies

（4）SAE 1095

• Carbon Content (%)：0.90–1.03

• Main Characteristics：Ultra-high carbon, extremely high hardness

• Typical Uses：Blades, springs

（5）Comparison Conclusion:

• SAE 1078 is much harder than low-carbon steels (such as SAE 1018), but more difficult to weld and cold form. 

• It has a slightly lower carbon content and better toughness compared to SAE 1095, but with slightly lower hardness.

6. Processing and Procurement

• Machining: High hardness leads to rapid tool wear, recommended to use carbide tools.

• Weldability: Poor, requires preheating (200–300°C) and low-hydrogen electrodes.

• Cold Forming: Low plasticity, requires annealing for softening before processing.

• Price Range: Approximately 12–35 RMB per kilogram (depending on specifications and order volume).

7. Conclusion

• Advantages:

High hardness, wear resistance, and suitable for heat treatment strengthening.

• Disadvantages:

Low plasticity, poor weldability, and prone to brittleness.

• Applications:

Ideal for tools, springs, and wear-resistant mechanical parts.

• SAE 1078provides an ideal balance of hardness, strength, and wear resistance, making it a versatile choice for demanding applications that require high performance and durability.

8. Contact Us

To inquire about our inventory of SAE 1078 materials, heat treatment services, or custom processing capabilities, feel free to get in touch with us:
Email: sale@bolaibao1.com
Website:https://www.blbmetal.com

Bolaibao(Suzhou) Metal Products Co., Ltd. — Your Trusted Partner for High-Performance Steel Solutions.