1080 steel is considered one of the common spring steel grades used in piano wires. Article here summarizes all important aspects related to 1080 high carbon steel including properties, composition, heat treatment, manufacturing, microstructural evolution, and much more.
What is 1080 Steel?
ASTM AISI 1080 steel is high carbon fully pearlitic steel having a carbon percentage between 0.75-0.88%. After heat treatment, this steel exhibits an optimum combination of elastic properties, high hardness, and low ductility. 1080 high carbon alloy finds applications in piano wires, springs, shafts, and in other automotive and suspension parts.
1080 Steel Composition
As you can see from AISI 1080 designation, it’s a pure alloying element with the minor addition of Mn. A detailed composition is given below;
| Elements | Wt% |
|---|---|
| C | 0.75-0.88 |
| Mn | 0.60-0.90 |
| P | <0.05 |
| S | <0.04 |
1080 Carbon Steel Properties
This steel is eutectoid steel containing a lamellar structure of pearlite. Mainly this steel is used after rolling and subsequent heat treatment because of its enhanced elastic properties, and fatigue resistance.
Physical Properties
| Properties | Units (metric) |
|---|---|
| Melting Point | 1430 C |
| Density | 7.85 g/cm3 |
Mechanical Properties
HB is used for the Brinell hardness test, HR is used for the Rockwell hardness test and HV is used for the Vicker hardness test.
| 1080 Mech Properties | As Rolled | Cold Drawn + Spherodized Annealed | Hot Rolled | Normalized | Oil Quenched | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Hardness, Brinell | 293 | 192 | 229 | 293 | 363 | |||||
| Hardness, Knoop | 319 | 214 | 252 | 319 | 392 | |||||
| Hardness, Rockwell B | 99 | 91 | 96 | 99 | 100 | |||||
| Hardness, Rockwell C | 31 | 11 | 19 | 31 | 40 | |||||
| Hardness, Vickers | 309 | 201 | 241 | 309 | 384 | |||||
| Tensile Strength, Ultimate | 965 MPa | 675 MPa | 772 MPa | 1035 MPa | 1270 MPa | |||||
| Tensile Strength, Yield | 585 MPa | 515 MPa | 425 MPa | 550 MPa | 869 MPa | |||||
| Elongation at Break | 0.12 | 0.1 | 0.1 | 0.124 | 0.121 | |||||
| Reduction of Area | 0.17 | 0.4 | 0.25 | 0.277 | 0.344 | |||||
| Modulus of Elasticity | 205 GPa | 205 GPa | 205 GPa | 200 GPa | 205 GPa | |||||
| Bulk Modulus | 160 GPa | 160 GPa | 160 GPa | 160 GPa | 160 GPa | |||||
| Poissons Ratio | 0.29 | 0.29 | 0.29 | 0.29 | 0.29 | |||||
| Shear Modulus | 80.0 GPa | 0.45 | 80.0 GPa | 80.0 GPa | 80.0 GPa | |||||
| Izod Impact | 7.00 J | 80.0 GPa | 7.00 J |
Thermal Properties
| 1080 steel | Thermal Properties in Metric Unit |
|---|---|
| Coefficient of Thermal Expansion | 11.0 µm/m-°C |
| Specific Heat Capacity | 0.490 J/g-°C |
| Thermal Conductivity | 47.7 W/m-K |
1080 Spring Steel Rolling
This steell is mainly used after the rolling or forging process to be used in wires, springs, or automotive parts. The rolling process not only reduces surface area but also increases tensile strength due to plastic deformation.
Plastic deformation refines microstructure and also reduces interlamellar spacing in pearlite. This refined microstructure and reduced interlamellar spacing increase tensile strength and fatigue resistance. With such refine microstructure, crack propagation is also controlled. However, in applications where sufficient ductility is pre-requirement, heat treatment processes are employed.
AISI 1080 Steel Heat treatment
Common processes employed on 1080 cold rolled steel Normalizing, annealing, and hardening.
Normalizing
Normalizing 1080 steel is an important process because it refines microstructure. This refined microstructure makes this steel suitable for springs and shafts.
The normalizing temperature for this steel is between 800-850oC.
Full Annealing
Incase of annealing, there is no sub-critical annealing region and the composition is closer to the eutectoid point. So, the Full annealing temperature of this specific grade of steel is lower as compared to other grades.
79-850o C is the optimum annealing range for 1080 high carbon colled rolled steel. Holding time for thickness less than 75mm size sample is 1 hr with addition half-hour for each 25.4 mm increase in sample size.
Quenching 1080 Steel
Hardening is extremely important to achieve desired hardness in the microstructure. To achieve a hardness of 65HRC measured on Rockwell hardness tester, water or bring quenching is used on 1080 grade.
Hardening temperature is similar to the above heat treatment processes i.e. 800-820oC.
Tempering 1080 Steel
Tempering of 1080 steel is extremely important to relieve quenching stresses. There are lots of quenching defects that can generate which can be removed in process of tempering.
The effect of tempering can be seen in the chart below. We explained the role of tempering on the microstructure of 1080 steel and its hardness in the article, “tempering steel process”. Give it a look, you will find all answers.
| After tempering for 2 h at °C (°F) | Rockwell C hardness, HRC |
|---|---|
| 205 (400) | 57 |
| 260 (500) | 55 |
| 315 (600) | 50 |
| 370 (700) | 43 |
| 425 (800) | 41 |
| 480 (900) | 40 |
| 540 (1000) | 39 |
| 595 (1100) | 38 |
| 650 (1200) | 32 |
In this chart above, steel is Normalized at 885 °C, and water quenched from 800-815 °C.
AISI 1080 Steel weldability
Steel starting from0.8% carbon has a major portion of cementite. These types of steel are not recommended for welding.
Microstructure Evolution
As mentioned earlier, this steel is eutectoid and, during cooling, this steel transforms into complete pearlite and no secondary phase i.e. ferrite or cementite nucleates. The right process of microstructure evolution can be studied in the annealing section.
The most important aspects of the 1080 grade microstructure are austenite initial grain size, interlamellar spacing, and strain hardening to determine resultant properties.
1080 carbon steel vs W2
1080 has a carbon percentage of 0.8% while, in the case of w2, it is 1.1%. W2 steel is low alloy high carbon steel with small additions of V, W, and Cr. With the addition of these alloying elements, high surface hardness, moderate toughness is achievable in W2 making it ideal for knives and swords. On the other hand, this steel is plain high carbon steel which is most suitable for cutting tools, cold drawn wires, and springs.
Regarding W2, read detailed review in article, W2 tool steel.
1080 steel VS 1095 steel
1095 steel has more carbon as compared to 1080 steel. High carbon leads to higher hardness and low ductility. 1095 steel is specifically used where high hardness and wear resistance is required like knives and cutting tools. While 1080 grade has good elastic properties with optimum hardness making it ideal for cold-drawn rods or piano wires.
FAQ
What is the hardening temp for 1080?
The hardening temperature for 1080 grade is 815o C. You can use water or brine solution for quenching.
How strong is 1080 steel at 56 HC hardened?
You can see the tempering chart in this article to see the exact process to achieve this hardness with tempering.
How to read it diagram for 1080?
Detailed description and microstructure evolution according to ttt diagram is explained in ttt diagram in steel.
What products are made of 1080?
The most common products made of this steel are piano wires, hand tools.
What is the carbon content of 1080 grade?
Carbon content of 1080 grade are 0.75% to 0.88%.
What is the chemical composition of 1080?
1080 is plain high carbon iron alloy with C-0.75-0.88%, Mn-0.6%, and trace elements of P, and S.
1080 steel uses
1080 is a widely used high carbon grade with applications in cutting tools, automotive parts, and high tension wires.
- One of the most common applications of this steel is piano wires.
- Other than piano wires, this steel is used in spring clamps, antennas, springs, and leaf springs.
- This steel is also used in the broad field of cutting tools i.e. hand tools, ring rolling tools, and hitting tools.
- In the automotive sector, this sector finds uses in the shaft and many other spare parts.
