SAE 1112 Steel: Properties and Key Applications
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Table Of Content
Table Of Content
SAE 1112 steel is classified as a low-carbon alloy steel, primarily known for its machinability and versatility in various engineering applications. This steel grade contains a relatively low carbon content, typically around 0.10% to 0.15%, which contributes to its excellent ductility and formability. The primary alloying elements in SAE 1112 include manganese (Mn), which enhances hardenability and strength, and sulfur (S), which improves machinability.
Comprehensive Overview
SAE 1112 is particularly valued in the manufacturing sector for its balance of strength, ductility, and machinability. It is often used in applications requiring intricate machining processes, such as the production of gears, shafts, and fasteners. The steel's low carbon content allows for good weldability and formability, making it suitable for various fabrication techniques.
Advantages of SAE 1112:
- Excellent Machinability: The presence of sulfur enhances the steel's machinability, making it easier to cut and shape.
- Good Ductility: Its low carbon content provides good elongation properties, allowing for deformation without fracture.
- Versatile Applications: Suitable for a wide range of applications in automotive and industrial sectors.
Limitations of SAE 1112:
- Limited Hardness: Compared to higher carbon steels, SAE 1112 may not achieve the same hardness levels, limiting its use in high-wear applications.
- Corrosion Resistance: It does not possess significant corrosion resistance, making it less suitable for environments prone to rust and oxidation.
Historically, SAE 1112 has been a staple in the production of precision components due to its favorable properties and ease of processing. Its market position remains strong, particularly in industries where high-volume production and precision are critical.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | G11120 | USA | Closest equivalent to AISI 1112 |
| AISI/SAE | 1112 | USA | Commonly used in the automotive industry |
| ASTM | A108 | USA | Standard specification for cold-finished carbon steel bars |
| EN | 1.0402 | Europe | Minor compositional differences to be aware of |
| JIS | S10C | Japan | Similar properties but different applications |
| ISO | 10120 | International | General equivalent for low-carbon steel |
The differences between these grades can affect selection based on specific application requirements. For instance, while AISI 1112 and UNS G11120 are closely related, the latter may have slightly different sulfur content, impacting machinability.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| C (Carbon) | 0.10 - 0.15 |
| Mn (Manganese) | 0.30 - 0.60 |
| S (Sulfur) | 0.15 - 0.35 |
| P (Phosphorus) | ≤ 0.04 |
| Fe (Iron) | Balance |
The primary role of the key alloying elements in SAE 1112 includes:
- Carbon (C): Provides strength and hardness; however, its low content ensures good ductility.
- Manganese (Mn): Enhances hardenability and tensile strength, contributing to the overall mechanical properties.
- Sulfur (S): Improves machinability by promoting chip formation during cutting processes.
Mechanical Properties
| Property | Condition/Temper | Typical Value/Range (Metric) | Typical Value/Range (Imperial) | Reference Standard for Test Method |
|---|---|---|---|---|
| Tensile Strength | Annealed | 370 - 480 MPa | 54 - 70 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | Annealed | 210 - 310 MPa | 30 - 45 ksi | ASTM E8 |
| Elongation | Annealed | 20 - 30% | 20 - 30% | ASTM E8 |
| Hardness (Rockwell B) | Annealed | 70 - 90 HRB | 70 - 90 HRB | ASTM E18 |
| Impact Strength (Charpy) | -20°C | 30 - 50 J | 22 - 37 ft-lbf | ASTM E23 |
The combination of these mechanical properties makes SAE 1112 suitable for applications that require good strength and ductility under mechanical loading. Its relatively high elongation percentage indicates that it can withstand significant deformation before failure, making it ideal for components subjected to dynamic loads.
Physical Properties
| Property | Condition/Temperature | Value (Metric) | Value (Imperial) |
|---|---|---|---|
| Density | - | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point/Range | - | 1425 - 1540 °C | 2600 - 2800 °F |
| Thermal Conductivity | 20°C | 50 W/m·K | 34.5 BTU·in/h·ft²·°F |
| Specific Heat Capacity | 20°C | 0.46 kJ/kg·K | 0.11 BTU/lb·°F |
| Electrical Resistivity | 20°C | 0.0000017 Ω·m | 0.0000017 Ω·in |
The practical significance of the density and melting point of SAE 1112 is crucial for applications involving high-temperature processes, such as forging and casting. Its thermal conductivity indicates that it can efficiently dissipate heat, which is beneficial in machining operations to prevent overheating.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C/°F) | Resistance Rating | Notes |
|---|---|---|---|---|
| Water | - | Ambient | Fair | Susceptible to rust |
| Acids (HCl) | 10% | 25°C/77°F | Poor | Risk of pitting |
| Alkalis (NaOH) | 5% | 25°C/77°F | Fair | Moderate resistance |
| Chlorides (NaCl) | 3% | 25°C/77°F | Poor | Risk of stress corrosion cracking |
SAE 1112 exhibits limited corrosion resistance, particularly in acidic and chloride environments. It is susceptible to rusting in humid conditions and may experience pitting in the presence of chlorides. Compared to stainless steels like AISI 304, which offers excellent corrosion resistance, SAE 1112 is less suitable for applications in corrosive environments.
Heat Resistance
| Property/Limit | Temperature (°C) | Temperature (°F) | Remarks |
|---|---|---|---|
| Max Continuous Service Temp | 300°C | 572°F | Beyond this, properties may degrade |
| Max Intermittent Service Temp | 400°C | 752°F | Short-term exposure may be tolerated |
| Scaling Temperature | 600°C | 1112°F | Risk of oxidation at elevated temperatures |
| Creep Strength considerations begin around | 400°C | 752°F | Creep may become significant |
At elevated temperatures, SAE 1112 maintains reasonable mechanical properties but may experience oxidation and scaling, particularly above 400°C. This can lead to a reduction in strength and ductility, making it less suitable for high-temperature applications compared to higher alloy steels.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| MIG | ER70S-6 | Argon + CO2 mix | Good for thin sections |
| TIG | ER70S-2 | Pure Argon | Requires preheat |
| Stick (SMAW) | E7018 | - | Suitable for general use |
SAE 1112 is generally considered to have good weldability, particularly with MIG and TIG processes. Preheating may be necessary to avoid cracking, especially in thicker sections. Post-weld heat treatment can help relieve stresses and improve the overall performance of the weld.
Machinability
| Machining Parameter | SAE 1112 | Benchmark Steel (AISI 1212) | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 100 | 130 | SAE 1112 is less machinable than AISI 1212 |
| Typical Cutting Speed | 30 m/min | 40 m/min | Adjust for tool wear |
SAE 1112 offers good machinability, though it is slightly less favorable than AISI 1212. Optimal cutting speeds and tooling should be selected to minimize wear and maximize efficiency during machining operations.
Formability
SAE 1112 exhibits good formability, making it suitable for cold and hot forming processes. It can be easily bent and shaped without significant risk of cracking. The work hardening rate is moderate, allowing for some deformation before reaching the yield point.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Annealing | 600 - 700 °C / 1112 - 1292 °F | 1 - 2 hours | Air | Improve ductility and reduce hardness |
| Normalizing | 800 - 900 °C / 1472 - 1652 °F | 1 - 2 hours | Air | Refine grain structure |
| Quenching | 850 - 900 °C / 1562 - 1652 °F | 1 hour | Oil or Water | Increase hardness |
During heat treatment, SAE 1112 undergoes metallurgical transformations that enhance its properties. Annealing softens the steel, improving ductility, while normalizing refines the grain structure, leading to improved toughness. Quenching can increase hardness but may require tempering to relieve stresses.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection (Brief) |
|---|---|---|---|
| Automotive | Gears | High machinability, good ductility | Precision components |
| Manufacturing | Fasteners | Excellent formability, weldability | High-volume production |
| Aerospace | Structural components | Good strength-to-weight ratio | Lightweight applications |
| Machinery | Shafts | High tensile strength, good impact resistance | Durability under load |
Other applications include:
- Construction: Used in structural components due to its strength and ease of fabrication.
- Electronics: Components requiring precise machining and low-cost production.
SAE 1112 is chosen for these applications due to its favorable balance of properties, making it ideal for high-volume production where precision and cost-effectiveness are critical.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | SAE 1112 | AISI 1018 | AISI 1212 | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | Moderate Strength | Lower Strength | Higher Strength | 1212 offers better machinability |
| Key Corrosion Aspect | Fair | Fair | Poor | All grades have limited corrosion resistance |
| Weldability | Good | Good | Fair | 1212 may require special care |
| Machinability | Good | Moderate | Excellent | 1212 is superior for machining |
| Formability | Good | Good | Fair | 1212 is less formable |
| Approx. Relative Cost | Moderate | Low | High | Cost varies with market demand |
| Typical Availability | Common | Very Common | Less Common | 1018 is widely available |
When selecting SAE 1112, considerations include cost-effectiveness, availability, and specific performance requirements. Its moderate cost and good availability make it a practical choice for many applications. However, for environments requiring higher corrosion resistance or wear resistance, alternative grades may be more suitable.
In summary, SAE 1112 steel is a versatile low-carbon alloy steel that excels in machinability and formability, making it a popular choice in various industries. Understanding its properties and limitations is crucial for selecting the right material for specific applications.
