Comprehensive Guide to SAE AISI 1020 Steel Properties
When it comes to selecting the right material for your engineering projects, understanding the nuances of different types of steel…
When it comes to versatile and reliable materials in the world of manufacturing and engineering, SAE AISI 1117 carbon steel stands out as a popular choice. Known for its exceptional machinability and balanced mechanical properties, this medium carbon steel plays a pivotal role in applications ranging from automotive components to industrial machinery. Its unique combination of strength, ductility, and the ability to undergo various heat treatments makes it a go-to material for engineers and manufacturers seeking precision and performance.
This article delves into the key aspects of SAE AISI 1117, exploring its chemical composition, mechanical properties, and the transformative effects of heat treatment. By understanding these attributes, you’ll gain insights into why this material is favored across industries and how it compares to other carbon steels like AISI 1018. Whether you’re a professional evaluating materials for your next project or a student looking to expand your knowledge, this guide offers a comprehensive view of what makes SAE AISI 1117 a standout choice.
AISI 1117 carbon steel, known by its UNS designation G11170, is a resulfurized carbon steel designed to improve machinability while maintaining strength. This balance of properties makes it a versatile material for various manufacturing and engineering applications.
AISI 1117 is highly valued for its excellent machinability, which is critical in industries that require precision machining. The addition of sulfur enhances machinability, making cutting processes easier and more efficient. This steel is commonly used in the automotive industry for making parts like shafts, gears, and fasteners, as well as in the production of valves, pumps, and other machinery components.
AISI 1117 carbon steel exhibits a unique set of properties that contribute to its widespread use:
AISI 1117 carbon steel is adaptable to various manufacturing processes such as hot-rolling, cold-finishing, and forging, and is available in multiple forms including bars, wire rods, plates, strips, sheets, and tubing.
In summary, AISI 1117 carbon steel’s unique composition and properties make it essential in industries requiring high machinability and reliable mechanical performance, particularly in automotive, valve, pump, and general engineering applications.
AISI 1117 carbon steel is designed with a precise chemical composition that optimizes machinability, strength, and performance. The primary elements in its composition include:
Carbon (C): 0.14–0.20%
Carbon adds hardness and strength, while its moderate level balances these qualities with machinability, ideal for precision machining.
Manganese (Mn): 1.00–1.30%
Manganese boosts hardenability, tensile strength, and heat treatment adaptability while reducing brittleness.
Sulfur (S): 0.08–0.13%
Sulfur enhances machinability by forming manganese sulfide inclusions, which act as lubricants during cutting.
Phosphorus (P): Up to 0.04%
Low phosphorus levels minimize brittleness, maintaining toughness while subtly enhancing machinability and corrosion resistance.
Iron (Fe): Approximately 98.3–98.8%
Iron, the primary element, forms the structural foundation and balances other alloying elements to achieve the desired mechanical properties.
While primarily composed of major elements, AISI 1117 also contains minor elements that fine-tune its properties:
Silicon (Si): Up to 0.10%
Silicon deoxidizes the steel and slightly enhances its strength.
Aluminium (Al): Up to 0.02%
Aluminium refines grain size, boosting toughness and ductility.
Niobium (Nb): Up to 0.025%
Niobium refines the grain structure, improving wear resistance and fatigue strength.
Vanadium (V): Up to 0.05%
Vanadium strengthens and improves wear resistance through grain refinement and precipitation hardening.
AISI 1117 stands out for its higher sulfur and manganese content. Compared to AISI 1018, it offers better machinability and hardenability, though slightly reduced ductility due to sulfur inclusions.
This precise chemical composition makes AISI 1117 an excellent choice for applications requiring a combination of moderate strength, high machinability, and good response to heat treatment.
Tensile strength measures the maximum stress AISI 1117 carbon steel can endure before breaking when stretched. Typically, it ranges from 430 to 480 MPa (62,000 to 69,900 psi). This ensures the steel can handle substantial force without failing, making it ideal for structural and mechanical applications.
Yield strength indicates the stress level where AISI 1117 starts to deform permanently. It generally ranges from 230 MPa (33,000 psi) to 400 MPa (58,000 psi), depending on the tempering process. This property is essential for maintaining shape under load without permanent deformation.
The elastic modulus, or Young’s modulus, measures the stiffness of AISI 1117. With a range of 190 to 210 GPa (27,557 to 30,458 ksi), this high stiffness helps the material resist deformation, ensuring structural integrity in demanding engineering applications.
Hardness measures resistance to permanent deformation. AISI 1117 has a Brinell hardness range of 121 to 248 HB, with equivalent values such as Rockwell B 75 and Vickers 143. Heat treatment can adjust the hardness, enhancing wear resistance and durability for various uses.
Elongation at break measures how much AISI 1117 can stretch before breaking, with a minimum elongation of 15% over a 50 mm gauge length. This property demonstrates its ability to absorb energy and deform significantly without fracturing, making it valuable in applications requiring flexibility and toughness.
Reduction of area reflects the steel’s ductility and resistance to cracking under deformation. For AISI 1117, this typically ranges from 40% to 47%, signifying its ability to undergo substantial deformation without cracking.
Poisson’s ratio, ranging from 0.27 to 0.30, describes the material’s tendency to expand in directions perpendicular to compression, ensuring predictable deformation under various loading conditions.
The impact strength of AISI 1117 is approximately 93.6 J when annealed at 855°C. This property ensures the steel can withstand shock loading by absorbing and dissipating energy without fracturing.
The mechanical properties of AISI 1117 carbon steel—such as its tensile strength, yield strength, stiffness, and ductility—make it a versatile and reliable choice for industrial applications. Balancing strength, machinability, and toughness, AISI 1117 is well-suited for structural and mechanical uses requiring durability and performance.
AISI 1117, a low-carbon steel, is widely used in industrial applications for its adaptability to various heat treatments that enhance its mechanical properties. By subjecting the material to controlled heating and cooling cycles, its hardness, strength, toughness, and machinability can be adjusted to suit specific applications.
Annealing involves heating AISI 1117 to a specified temperature followed by slow cooling. This process aims to:
Typically, AISI 1117 is annealed at temperatures around 815–870°C (1500–1600°F) before being cooled in the furnace.
For applications requiring uniform strength, normalizing is a key process. It involves heating AISI 1117 above its critical transformation temperature, followed by air cooling. The objectives of normalizing include:
Hardening AISI 1117 involves heating the steel to a high temperature, followed by rapid quenching in water or oil. While hardening enhances wear resistance, it increases brittleness, requiring tempering for balance.
Tempering is performed after hardening to reduce brittleness while maintaining the desired hardness. AISI 1117 is reheated to a lower temperature, depending on the required balance of mechanical properties. This step allows for:
Carburization is a surface-hardening technique often applied to AISI 1117. The steel is exposed to a carbon-rich environment at high temperatures. This process:
Each heat treatment process uniquely tailors AISI 1117’s properties, ensuring suitability for diverse industrial needs:
By selecting the appropriate heat treatment process, AISI 1117 can be tailored to meet the specific demands of various industrial applications.
AISI 1117 carbon steel is a popular choice in the automotive industry due to its excellent machinability and moderate strength. It is ideal for precision parts like tie rods and steering shafts, and is also used for gears and sprockets requiring wear resistance and toughness, often improved by carburization. AISI 1117 ensures durability and reliability for axles and drive shafts, especially under cyclic loading conditions. Additionally, this steel is commonly used for bolts, screws, and studs, where consistent strength and machinability are essential.
The excellent machinability of AISI 1117 makes it ideal for valve stems and seats, providing a balance of machinability and wear resistance. It ensures dimensional accuracy and smooth surface finishes, which are critical for sealing and operational efficiency in pump shafts. AISI 1117 is also used in couplings and connectors due to its structural reliability.
AISI 1117 is widely used in general engineering for its adaptability to machining and heat treatment processes. It is suitable for low-stress frameworks and brackets, and is ideal for precision parts like bushings, spacers, and collars in industrial machinery.
In manufacturing, AISI 1117’s machinability and formability make it suitable for high-volume production. It is frequently chosen for CNC-machined parts requiring tight tolerances, and is applied in jigs and fixtures where durability and precision alignment are necessary.
AISI 1117’s versatility extends to various specialized industries, making it suitable for shafts and spindles in textile machinery. It is used for linkages and couplings in agricultural equipment due to its toughness and wear resistance. Additionally, AISI 1117 is applied in construction equipment parts that require moderate strength and machinability, such as hinges and mounting brackets.
Overall, AISI 1117’s combination of machinability, strength, and versatility makes it an indispensable material across various industrial applications, meeting diverse operational needs.
AISI 1117 and AISI 1018 share similarities in carbon content but differ significantly in other elemental compositions, with AISI 1117 containing 0.14-0.20% Carbon, 1.00-1.30% Manganese, 0.080-0.13% Sulfur, and up to 0.040% Phosphorus. The sulfur in AISI 1117 improves machinability, making it more suitable for machining-intensive applications than AISI 1018, which lacks deliberate sulfur additions and contains 0.15-0.20% Carbon and 0.60-0.90% Manganese.
AISI 1045 has a higher carbon content (0.42-0.50%) than AISI 1117, resulting in greater hardness and strength but lower machinability. AISI 1045 also contains less manganese (0.60-0.90%) and negligible sulfur, making it less favorable for applications requiring extensive machining compared to AISI 1117.
AISI 1117 has an ultimate tensile strength of 490 to 540 MPa and a yield strength of 260 to 460 MPa. AISI 1018 generally shows slightly lower tensile and yield strengths due to its lower manganese content and lack of sulfur. In contrast, AISI 1045, with its higher carbon content, offers greater tensile and yield strengths, making it ideal for load-bearing applications.
AISI 1117 has a Brinell hardness of 140 to 150, slightly higher than AISI 1018 but lower than AISI 1045, which ranges from 170 to 210. While the sulfur in AISI 1117 enhances machinability, it slightly reduces ductility. AISI 1018 and AISI 1045 maintain better ductility, though this comes at the cost of reduced machinability.
AISI 1117 is known for its excellent machinability due to the presence of sulfur, which forms manganese sulfide inclusions that act as lubricants during machining. This makes it ideal for high-speed machining. While AISI 1018 is easier to form and weld, it does not match AISI 1117’s machinability. AISI 1045, with its higher hardness, is more challenging to machine but offers better wear resistance for demanding applications.
AISI 1117’s higher manganese content provides better hardenability than AISI 1018, making it more suitable for applications requiring heat treatment to enhance surface hardness and wear resistance. AISI 1045, with its higher carbon content, also exhibits good hardenability, but it tends to become more brittle after heat treatment, limiting its use in applications needing toughness.
AISI 1117’s superior machinability makes it ideal for parts like valve stems, pump shafts, and automotive gears, where precise machining is essential. AISI 1018 is better suited for structural applications and general engineering purposes where machinability is less critical. AISI 1045, with its high strength and hardness, is commonly used in high-stress components such as axles, bolts, and large gears.
AISI 1117 offers several advantages, including superior machinability, good hardenability, and a balanced combination of strength and ductility. However, it has slightly lower ductility due to sulfur and is less suitable for high-strength applications that do not require extensive machining, where steels like AISI 1045 are more appropriate.
Below are answers to some frequently asked questions:
The chemical components of AISI 1117 carbon steel are as follows: Carbon (C) ranges from 0.14% to 0.20%, Manganese (Mn) from 1.00% to 1.30%, Sulfur (S) from 0.080% to 0.13%, and Phosphorus (P) is a maximum of 0.040%. The balance is primarily Iron (Fe), typically between 98.3% to 98.8%. Additionally, minor elements include Aluminium (Al) with a maximum of 0.020%, Niobium (Nb) with a maximum of 0.025%, Silicon (Si) with a maximum of 0.100%, and Vanadium (V) with a maximum of 0.050%. These components collectively contribute to the steel’s desirable properties for various industrial applications.
The mechanical properties of AISI 1117 carbon steel include an ultimate tensile strength ranging from 429.5 MPa to 540 MPa, and a yield strength between 230 MPa and 460 MPa, depending on the heat treatment. The elongation at break is between 15% and 32.8%, indicating good ductility. The reduction in area ranges from 40% to 58%, further demonstrating its ability to deform without breaking. The Brinell hardness varies from 121 HB to 190 HB, with cold-drawn conditions yielding values between 160 BHN and 190 BHN. The elastic modulus is between 190 GPa and 210 GPa, the Poisson’s ratio is 0.27 to 0.30, and the shear modulus is approximately 73 GPa to 80 GPa. The shear strength is around 320 MPa to 330 MPa, and the impact strength, measured by the Izod test, is approximately 93.6 J in annealed conditions. These properties make AISI 1117 suitable for applications requiring excellent machinability and surface finish, such as gears, studs, shafts, and steering components.
AISI 1117 carbon steel is commonly used in applications requiring excellent machinability and moderate mechanical strength. It is widely employed in the production of automatic screw machine parts, gears, shafts, studs, and pinions. Its favorable hardenability and ability to undergo deep and uniform case hardening make it ideal for carburized parts such as king pins, ratchets, and camshafts. Additionally, it is utilized in the manufacturing of valve and pump components and various general engineering applications, particularly where good machinability and reliable mechanical properties are essential.
AISI 1117 carbon steel can be heat-treated through several methods to improve its performance. Annealing involves heating the steel to a specific temperature and then cooling it slowly to relieve internal stresses and increase ductility, making it easier to machine and form. Normalizing entails heating the steel above its critical temperature (around 900°C) and cooling it in air, which refines the grain structure and enhances toughness and overall mechanical properties. While hardening by heating to the austenitizing temperature (approximately 850°C) and quenching can create a hard martensitic structure, it is less common for AISI 1117 due to its resulfurized nature, which is better suited for free-machining applications rather than high-strength requirements. Tempering, following hardening, involves reheating to a lower temperature to reduce brittleness, but this is also less typical for AISI 1117. The specific heat treatment chosen depends on the desired balance between machinability, formability, and mechanical strength for the intended application.
AISI 1117 differs from AISI 1018 primarily in its composition and performance characteristics. AISI 1117 has higher manganese content (1.00–1.30%) and includes sulfur (0.080–0.13%), which enhance its machinability and hardenability. In contrast, AISI 1018 has lower manganese (0.60–0.90%) and sulfur levels, making it less specialized for machining but more versatile for general engineering applications.
Mechanically, AISI 1117 offers higher tensile strength, yield strength, and hardness compared to AISI 1018, along with deep, uniform case hardening properties, making it ideal for applications like gears, shafts, and carburized parts. AISI 1018, while having good machinability and adequate strength, is better suited for less demanding applications where precision machining and hardening are not critical. These distinctions make AISI 1117 more suitable for specialized uses requiring close tolerances and excellent machinability.
