Alloy Steel vs. Stainless Steel
Learn more about the differences between alloy steel and stainless steel and their properties.
Alloy steel is a metal consisting mainly of iron but which includes small amounts of other elements such as: carbon, chromium, manganese, molybdenum, nickel, silicon, tungsten, or vanadium. These elements are added to alter the physical properties of the steel to improve such things as hardness, strength, or corrosion resistance. Alloy steel is often used in applications that require high strength, such as construction or manufacturing.
Stainless steel is a specific type of alloy steel that contains a relatively large proportion of chromium. The added element gives this metal its distinctive shine and corrosion resistance. Stainless steel is often used in kitchenware, medical equipment, or exposed architectural elements. Stainless steel is more resistant to corrosion than most other steel alloys, but it is often not as strong. This article will further compare alloy steel vs. stainless steel in terms of their properties and applications to give you a better understanding of which one might be best for your next project.
What is Alloy Steel?
Alloy steel is a catch-all category for steel materials that contain one or more alloying elements (a substance added to another material to improve its properties). All basic steel consists of iron and a small amount of carbon. The most common additional alloying element is chromium, which gives steel corrosion-resistant properties. Other elements that can be used to alloy steel include: manganese, molybdenum, nickel, titanium, tungsten, and vanadium. The properties of alloy steel depend on the specific elements that are added to it. For example, chromium increases the hardness, wear resistance, and toughness of steel while manganese increases its ductility, hardenability, and wear resistance.
For more information, see our guide on All About Alloy Steel.
What is Stainless Steel?
Stainless steel is a type of alloyed steel that contains at least 10.5% chromium, making it highly resistant to corrosion. The added chromium makes it an ideal material for a wide range of applications, from cookware to medical equipment. Its unique properties make it a popular choice for consumers and businesses alike. It is important to note that there are also different grades of stainless steel, each with its own set of properties.
What Are the Properties of Alloy Steel?
Table 1 highlights the properties of Alloy Steel:
| Physical Properties | Chemical Properties |
|---|---|
Physical Properties High strength-to-weight ratio. | Chemical Properties Contains high levels of chromium, molybdenum, and/or other alloying elements. |
Physical Properties Good corrosion resistance | Chemical Properties The higher levels of alloying elements often allow alloys to be heat-treated to a wide range of hardness levels. |
Physical Properties High strength and durability | Chemical Properties |
Physical Properties Resistance to wear | Chemical Properties |
Physical Properties Hardness at high temperatures | Chemical Properties |
| Physical Properties | Chemical Properties |
|---|---|
Physical Properties Resistant to corrosion and staining | Chemical Properties Resistant to bases, acids, and also organic compounds |
Physical Properties Durable | Chemical Properties Composed of iron, chromium, and carbon. Some varieties may include manganese, silicon, nickel, or other elements |
Physical Properties Easy to clean and maintain | Chemical Properties |
Physical Properties Non-magnetic | Chemical Properties |
Physical Properties High resistance to heat | Chemical Properties |
Physical Properties Electrically conductive | Chemical Properties |
What Are the Types of Stainless Steel?
Thousands of different grades of stainless steel have been formulated, but they can be categorized into four distinct groups:
- Austenitic Stainless Steels: This group contains at least 16% chromium and 6% nickel (the basic grade 304 is 18% chromium, 8% nickel). It is widely used in chemical plants and food processing equipment because it will not readily corrode, rust, or stain after contact with water.
- Ferritic Stainless Steels: This group contains chromium (usually between 11 and 27%) and little or no nickel. They are less corrosion-resistant than the austenitic grades but are more iron-like and exhibit better mechanical properties at elevated temperatures.
- Martensitic Stainless Steels: This group contains chromium (between 14 and 18%) and moderate levels of carbon (usually between 0.2% and 1.2%). They can be hardened and tempered like carbon steel.
- Duplex Stainless Steels: This group contains chromium (between 18 and 28%) and nickel (between 3.5% and 5.5%). They have better corrosion resistance than the austenitic grades and, because of their lower carbon content, are less susceptible to embrittlement than the martensitic grades.
What Are the Types of Alloy Steel?
The broad categories of alloy steel are listed below:
- Low-Alloy Steels: Low-alloy steels contain a small amount of one or more alloying elements to improve strength, hardness, toughness, or other properties. Examples of common alloying elements are: chromium, nickel, manganese, and molybdenum. Low-alloy steels are typically used in equipment that requires good strength-to-weight ratios, such as construction and mining equipment.
- High-Alloy Steels: High-alloy steels contain a large amount of one or more alloying elements to improve strength, hardness, or toughness. Common alloying elements include: chromium, manganese, nickel, molybdenum, and vanadium.
- Tool Steels: Tool steels are highly alloyed and particularly well-suited for use in tool and die applications. Tool steels are designed to maintain their hardness and wear resistance at high temperatures.
- Maraging Steels: Maraging steels are known for their superior strength and toughness. They are typically used in applications that demand high strength, such as aerospace and military applications.
What Are the Advantages of Alloy Steel Compared to Stainless Steel?
Listed below are the advantages of alloy steel compared to stainless steel:
- Alloy steel is more resistant to wear and tear compared to stainless steel.
- Alloy steels are easier to weld compared to stainless. Though stainless steel is weldable, the process is not easy as other welds.
- Alloy steel is less expensive and can easily be machined compared to standard stainless grades
- Alloy steels are more durable than stainless steel.
What Are the Disadvantages of Alloy Steel Compared to Stainless Steel?
Listed below are the disadvantages of alloy steel compared to stainless steel:
- Alloy steel is less resistant to corrosion compared to Stainless steel. As a result, it requires a protective finish after manufacturing.
- Alloy steel has low strength at high temperatures.
- An alloy steel surface finish is not as good as that of stainless steel.
What Are the Comparisons Between Alloy Steel and Stainless Steel?
Table 3 compares alloy steel vs. stainless steel in terms of thermal conductivity, tensile strength, and application:
| Alloy Steel | Stainless Steel | |
|---|---|---|
Alloy Steel Thermal Conductivity | Stainless Steel Has a thermal conductivity of about 45 W/(mK). | Has a thermal conductivity of 15 W/(mK). |
Alloy Steel Tensile Strength | Stainless Steel More durable and has a tensile strength of up to 960 Mpa | Less durable and has a tensile strength of about 621 Mpa |
Alloy Steel Application | Stainless Steel Often used in construction and manufacturing | Commonly used in the food and beverage industry |
What Are the Mutual Alternatives to Alloy Steel and Stainless Steel?
Some of the mutual alternatives to traditional alloy steel and stainless steel are:
- Titanium Alloys: Titanium alloys are known for their high strength-to-weight ratios. These properties make them an ideal choice for many applications where weight is a concern.
- Aluminum Alloys: Aluminum alloys are often used in applications where strength and weight are both important considerations.
What Are the Similarities Between Alloy Steel and Stainless Steel?
Stainless steel is technically a specific type of alloy steel. Both contain a variety of elements, making them very versatile materials. Many alloys contain chromium, the key element in stainless steel. Chromium-laced steel resists corrosion because the added element forms a protective layer on the surface of the metal. Additionally, stainless, alloy, and all other types of steel are created from iron and carbon. When combined in the right ratio, these elements form a very strong and durable molecular lattice. Finally, stainless steel and most other alloys can be heat-treated to improve their properties making them highly versatile materials that can be customized to suit a wide range of applications.
What Are the Other Comparisons for Stainless Steel Besides Alloy Steel?
Stainless steel is often compared against several other similar materials:
- Carbon Steel: Carbon steel is one of the most common types of steel. It is known for its strength and durability. Carbon steel is also less expensive than stainless steel, making it a popular choice for a variety of applications. The downside is that it rusts.
- Tool Steel: Tool steel is a type of carbon steel that is well-suited for making tools. It is known for its hardness and resistance to wear, a fact that manufacturers exploit for such items as knives, saws, and drill bits.
What Are the Other Comparisons for Alloy Steel Besides Stainless Steel?
Other materials one might choose instead of alloy steel include:
- Aluminum: Aluminum is the most common type of material used in automobile manufacturing. Water does not cause it to corrode the way iron-based metals do. Plus, Aluminum is both lightweight and very strong, making it ideal for car body panels and other structural components.
- Chromium-vanadium: The combination of chromium and vanadium atoms create lattice structures with very favorable strength-to-weight ratios, making it ideal for applications that require a strong material that is still lightweight. Because of its strength, it is often used in the manufacture of cutting tools.
Summary
This article presented alloy steel and stainless steel, explained what they are, and discussed the different properties and uses of each. To learn more about alloy steel and stainless steel contact a Xometry representative.
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