We need sturdy materials we can easily shape and weld into our required design in the industry. From plastics to aluminum, we have no shortage of materials. But stainless steel is one of the most commonly used industrial materials.
One of the many stainless steel types is AISI 1018, and in this article, we’ll discuss it in detail.
What is AISI 1018?
AISI refers to the American Institute for Steel and Iron. It standardizes steel and iron production and processing in the United States. One of its approved steel grades is AISI 1018. It is a modern-day alloy and one of the many types of carbon steel.
AISI 1018 is a mild/low-carbon steel alloy. It typically contains just 0.18% of carbon, which makes it easier to weld, form, and machine. As a result, you use it in industries where you require good machinability, such as automobiles.
What are the Properties of AISI 1018?
AISI 1018 is a versatile material, having the following properties:
AISI 1018 is an alloy of just three elements – iron, carbon, and manganese, with some sulfur and phosphorus impurities. Generally, the alloy contains between 0.15-0.20% of carbon, 0.60% to 0.90% of manganese, and trace amounts of sulfur and phosphorus. Over 99% of the AISI 1018 is composed of iron.
You may ask how does the composition of AISI 1018 affect its properties? The low carbon content makes welding and machining AISI 1018 steel easy, while the manganese content provides durability and strength.
- Tensile Strength: It has a moderate tensile strength of about 400-650 MPa.
- Yield Strength: Its yield strength is around 350 MPa, which is decent.
- Elongation: Its elongation is a good 15-20%.
- Hardness: Its Brinell hardness is around 126, low to moderate.
- Modulus of Elasticity: AISI 1018’s modulus of elasticity is 205 GPa, which indicates decent elasticity.
- Density: Its density is around 7.87 grams per cubic centimeter, which is close to iron’s density,
- Melting Point: Its melting point is around 1450-1500 degrees Celsius, making it able to withstand high temperatures.
- Thermal Conductivity: AISI 1018 has a thermal conductivity of 49.8 W/mK, indicating high conductivity.
- Electrical Conductivity: The steel has an electrical conductivity of 3.5-4.5 MS/m at room temperature, indicating it is a poor conductor of electricity but can be used in some electronics.
- Thermal Expansion: AISI 1018’s coefficient of thermal expansion is around 11.7 µm/m°C, which is moderate.
What are the Applications of AISI 1018?
AISI 1018 has several applications, including:
Some of its applications in manufacturing include:
- Automotive Industry:. It is used to make crankshafts, pistons, gears, and transmission parts.
- Aerospace Industry:. SS 1018 has a good strength-to-weight ratio, and is used here to make fasteners and pins.
- Agricultural Industry: You can use AISI 1018 to make tillers, plows, and cultivators.
- Oil and Gas Industry: Due to its ductility and elasticity, you can use it to make valves and fittings in the oil and gas industry.
AISI 1018 has several commercial applications, including:
- Bicycle frames.
- Kitchen utensils and cutlery.
- Sports equipment like golf clubs.
- Common hardware tools like wrenches and pliers.
You can use AISI 1018 steel in the construction industry. Common applications include:
- Structural support, like beams and columns.
- Reinforcing bars in concrete construction.
- Bolts, screws, and fasteners.
- Handrails and guardrails.
- Stair components.
Manufacturing AISI 1018
The manufacturing process of AISI 1018 is similar to how other SS grades are manufactured. The process starts by using an electric air furnace and a basic oxygen furnace to melt the iron, carbon, and manganese raw material and remove any impurities.
You then take the molten metal into a casting chamber, solidifying it into slabs or billets. You then subject it to hot rolling or heating it above its recrystallization temperature and rolling it into a desired shape.
Cold Working and Heat Treatment of AISI 1018
How is AISI 1018 forged and annealed? You do it through cold working and heat treatment.
In cold working, you deform it at room temperature to increase strength and hardness. Cold working processes include cold drawing, cold rolling, and cold forging.
You pull it through a die in the cold drawing process to reduce its diameter. In cold rolling, you pass it through rollers to reduce its thickness. In cold forging, you hammer or press the steel to shape it.
Likewise, you can give AISI 1018 heat treatment to improve its hardness and durability. The most common heat treatment for AISI 1018 is the annealing process. In this process, you heat the steel to a high temperature and then cool it slowly.
Advantages and Disadvantages of AISI 1018
AISI 1018 steel is weldable and formable but has less wear or corrosion resistance. Let’s discuss its feasibility in detail:
Advantages of AISI 1018
AISI 1018 has several pros, such as:
- Weldability: AISI 1018 has excellent weldability. Several welding techniques, like TIG or MIG, can be used on AISI 1018 components.
- Machinability: You can easily cut and shape AISI 1018 using different machines.
- Ductility: AISI 1018 can be drawn into different shapes without cracking.
- Low Cost: AISI 1018 is inexpensive and will lower your production costs.
Disadvantages of AISI 1018
AISI 1018 has many limitations in addition to its benefits. These include:
- Low Hardness: AISI 1018 is not very strong and tough and cannot be used where you require a sturdy material.
- Less Corrosion Resistance: AISI 1018 steel can rust easily, making it unsuitable for corrosive environments.
- Limited Wear Resistance: An AISI 1018 component can wear quickly. Do not use this steel in highly abrasive environments.
How Does AISI 1018 Compare to Other Carbon Steels?
AISI 1018 is a type of low-carbon steel. There are many other types of carbon steels, like AISI 1020, 1045, and 4140. Let’s compare them:
AISI 1018 vs. AISI 1020
AISI 1020 has a higher carbon content than AISI 1018. As a result, AISI 1020 is slightly more durable and hard, making it suitable for applications requiring strength and toughness. However, it is less machinable and formable than AISI 1018.
The difference between the two grades’ carbon content is minute; you can use them almost interchangeably.
AISI 1018 vs. AISI 1045
Another carbon steel is AISI 1045, which contains significantly higher carbon. It is a medium carbon steel, making it significantly more durable and hard.
However, it is less machineable and weldable than AISI 1018. You usually use AISI 1045 in shafts and gears requiring higher wear resistance.
AISI 1018 vs. AISI 4140
AISI 4140 is a high-carbon and high-strength steel alloy. It has significantly more carbon content.
It also contains chromium and molybdenum, making it extremely tough and suitable for the aerospace and oil and gas industries. However, it has considerably less ductility than AISI 1018.
What is the Machinability of AISI 1018?
Machinability is a material’s ability to be cut into shapes by machines. The higher the material’s machinability, the easier to make complex parts using a machine.
AISI 1018 is very machinable, and you can machine it using drills, lathes, and milling machines.
One machining tactic is chip formation. It refers to removing material from the workpiece when you machine it. Chip formation is continuous and easy in AISI 1018, making long and stringy chips with a blue or yellow color.
As the material has excellent machinability, the machine you use to cut it does not have to exert a lot of cutting force, ensuring it lasts for long.
Can AISI 1018 Be Welded?
Due to the low carbon content and excellent machinability, you can weld AISI 1018 easily. It can cause cracking and distortion, but you can reduce these with effective pre-welding and post-welding treatment.
In pre-welding treatment, you remove any surface contaminants like oil or dirt. After welding, you should give a post-welding treatment that relieves the welded joint of stress.
You can do this by heating the component and cooling it slowly. Doing so will prevent cracking and distortion.
You can weld AISI 1018 by any of the common welding methods. Use Gas Metal Arc Welding and Gas Tungsten Arc Welding for thin sections of AISI 1018, but Shield Metal Arc Welding for thicker sections.
SS 1018’s Resistance to Corrosion
AISI 1018 is generally less corrosion-resistant than other stainless steel grades. It shows limited resistance to different types of corrosion:
Pitting Corrosion Resistance of AISI 1018
Pitting corrosion is localized corrosion caused by acids or strong bases. It creates small pits or holes in the steel surface. AISI 1018 has moderate resistance against pitting corrosion and is especially susceptible in chloride-rich environments.
Crevice Corrosion Resistance of AISI 1018
Crevice corrosion is the rusting of steel in narrow gaps between two surfaces. Oxygen concentration is low in the crevices, so corrosion agents can effectively work in those gaps. AISI 1018 is very susceptible to it.
Intergranular Corrosion Resistance of AISI 1018
Intergranular corrosion is corrosion at the material’s grain boundaries. AISI 1018, when exposed to high temperatures for long times, becomes prone to intergranular corrosion.
Stress Corrosion Cracking Resistance of AISI 1018
Stress corrosion cracking happens when a material is under tensile stress, and corrosion agents like hydrogen sulfides act on it. AISI 1018 is prone to it.
Surface Finish of AISI 1018
Surface finish refers to the texture or smoothness of a surface after it is machined. You use AISI 1018 for industrial or commercial purposes, where you generally don’t need a smooth surface finish.
Generally, AISI 1018 has a rough surface. However, you can smoothen it using cutting tools and machines that give a smoother surface.
Additionally, you can use surface treatment methods to get a smoother surface. They include case hardening, where you add a thin layer of carbon or nitrogen on the surface. This will give a smoother surface and make the material more durable.
To improve corrosion resistance and aesthetic appeal, you can also electroplate the surface with another metal, like zinc or chromium. You can also get a black oxide coating to give the steel a black appearance and make it corrosion-resistant.
What is the Fatigue Resistance of AISI 1018?
A material’s fatigue resistance or strength is the maximum stress it can take for many cycles without breaking. It depends upon the tensile strength and loading conditions, and for AISI 1018, it is around 220-320 MPa.
The fatigue life is the number of cycles you can apply stress before the material breaks. For AISI 1018, it is generally 1000 to 100,000 cycles.
The fatigue strength depends on:.
- Surface Conditions: Scratches or cracks on the surface reduce the fatigue strength of AISI 1018.
- Loading Conditions: The higher the stress amplitude, mean stress level, and stress frequency, the lower the fatigue strength generally is.
- Environmental Factors: Temperature and corrosion can impact fatigue strength. Increased temperatures lead to lower fatigue strength. Also, corroded materials have less fatigue strength.
Maintenance of AISI 1018
You should often inspect your AISI 1018 components for wear, corrosion, and damage. Here’s how you can fix common issues:
- Corrosion: AISI 1018 is susceptible to corrosion, so don’t store it in salty or humid environments. Apply a protective coating, like black oxide or oil, to protect it from corrosion.
- Wear: AISI 1018 can wear down over time if exposed to abrasive materials. You can prevent it by keeping your IASI 1018 appliances well-lubricated.
- Heat Damage: Your AISI 1018 components can get damaged at high temperatures. You can use annealing and quenching techniques to prevent heat damage.
Environmental Impact of AISI 1018
You can recycle AISI 1018 and melt its scrap to make new products. So, AISI 1018 is a sustainable and environmentally friendly material.
The environmental benefits of AISI 1018 include its reduced waste generation, as you can reuse and recycle it once its lifespan ends. By recycling, you can also conserve natural resources like iron ore, as you need to mine less.
However, the production process is not entirely environmentally friendly. You must melt the ores at high temperatures, which causes CO2 emissions, and use fossil fuels. The production process also generates some waste, like slag and dust.
AISI 1018 is a low-carbon steel grade primarily used for its weldability and formability. It is cost-effective and machineable and does not offer high wear resistance, corrosion resistance, or durability.
You can use AISI 1018 parts in industries like automotive, oil and gas, and construction. Usually, you use it for complex parts that require complex steel machining.
AISI 1018 is recyclable and sustainable, and you can increase its durability through proper maintenance, heat treatment, and surface coating.
If AISI 1018 suits your projects, reach out to us for your steel sheets!
Frequently Asked Questions
2. Is AISI 1018 magnetic?
Yes, AISI 1018 is magnetic.
3. Can AISI 1018 be used for welding?
Yes, AISI 1018 is a weldable steel grade. However, you should give it pre-weld and post-weld treatment for a smooth weld.
5. How is the fatigue strength of AISI 1018?
AISI 1018 is a low-carbon steel with a low tensile strength, meaning its fatigue strength is lower than other steel grades.