Alloy Steel vs Stainless Steel: What’s the Difference?
Steel is opted for manufacturing components for different industries. However, there are different types of steel, among which alloy steel and stainless steel are prevalent. The two of these types of steel vary and have some differences as well.
If you are looking to learn about the comparison and difference between alloy steel vs stainless steel, the guide below will help you.
Alloy Steel Overview
Alloy steel has multiple alloying elements. Every alloying element adds new characteristics and enhances the properties of the material. It has iron, carbon, chromium, and other elements alloyed to enhance its properties.
Types of Alloy Steel
The different types of alloy steel are as follows:
High-Alloy Steels
High-alloy steel has a high amount of alloying elements, which adds strength, hardness, and toughness. The common elements used for alloying in high-alloy steel are manganese, vanadium, nickel, and chromium.
Low-Alloy Steels
Low alloy steel is composed of a low alloying element; it also adds properties like strength to the material. Materials used for alloying are copper, manganese, nickel, tungsten, molybdenum, and boron.
These low-alloy steels are used in mining and construction as they offer a high strength-to-weight ratio.
Maraging Steels
Maraging steel is opted for its strength and toughness, and it is used in applications that need high-strength properties like aerospace and military.
Tool Steels
Tool steel is known as steel that has a high alloy content and is used in tool and die applications. The tool steel is capable of resisting wear hardness when subjected to extreme temperatures.
Advantages of Alloy Steel over Stainless Steel
Alloy steel has various benefits over stainless steel, which makes it suitable for different applications. Some of these applications are as follows:
- Alloy steel offers a high ratio of strength to weight.
- It exhibits resistance against high temperatures.
- Alloy steel offers high machinability and supporting versatility.
- Alloy steel is an affordable option.
Stainless Steel Overview
Stainless steel is also an alloyed steel. Stainless steel composition has chromium of about 10.5%, and it offers resistance against corrosion. It is also suitable for many applications ranging from cookware to medicine.
Types of Stainless Steel
Some of the types of stainless steel are given below:
Austenitic Stainless Steels
Austenitic stainless steel is composed of nickel of 8% to 20% and chromium of 17% to 25%. Austenitic steel is a non-magnetic steel that is used in chemical plants and food processing machines.
It is highly resistant to stains and rust. It offers excellent weldability and formability.
Martensitic Stainless Steels
Martensitic stainless steel has chromium of about 14 to 18%, followed by carbon ranging between 0.2% to 2%. This form of steel can be hardened by tempering. Stainless steel grades 420C and 431 are the martensitic stainless steel grades.
Ferritic Stainless Steels
Ferritic stainless steel has 11 to 27% of chromium and a negligible amount of nickel. It is less resistant to corrosion and has enhanced mechanical properties.
This type of stainless steel can be hardened by annealing. This type of steel can be in sheet and coil. 430 and 409 stainless steel are examples of ferritic stainless steel.
Duplex Stainless Steels
Duplex stainless steel has 18 to 28% of chromium and 3.5 to 5.5% of nickel. It is highly weldable and can be fabricated easily. It offers enhanced corrosion and is magnetic.
Precipitation-hardening Stainless Steel Grades
It has 12 to 16% chromium, 3 to 8% nickel, and some proportion of elements like copper and titanium. It is ductile and strong; it can also be heat-treated.
Advantages of Stainless Steel Over Alloy Steel
Stainless steel has various advantages over alloy steel, and these are as follows:
- Stainless steel has low maintenance requirements.
- It is highly recyclable.
- The aesthetic look of stainless steel is better
- Stainless steel is highly resistant to corrosion.
Common Alloying Elements and Their Effects
The effects of different alloying elements are as follows:
Nickel
Nickel enhances the mechanical properties of steel. When used in higher percentages, it can enhance its corrosion resistance.
Tungsten
Tungsten is an alloying element that has the ability to enhance the structural formability of the steel alloy and its resistance against heat.
Chromium
Chromium enhances the material hardness of stainless steel. The higher the properties of chromium, the harder the material is.
Manganese
Manganese, when used with a little sulfur and phosphorus, ensures that the formed steel is less brittle and more malleable.
Vanadium
Vanadium can improve the heat resistance and strength of carbon steel and doesn't even compromise the formability.
Differences Between Alloy Steel vs Stainless Steel
This section highlights in detail the differences between stainless steel and alloy steel, and some of these differences are as follows:
Hardness
Hardness measures the ability of the material to resist abrasion and wear based on the heat treatment and composition of the material.
The alloying elements are less than 5%, and the steel has a higher hardness compared to stainless steel.
Ductility
Ductility is the measure of the material to elongate without cracking or breaking. Alloy steels offer ductility compared to stainless steel and, hence, are suitable for applications that need forming shapes.
Weldability
Alloy steel is not easily weldable, whereas stainless steel offers ease in weldability.
Formability
Alloy steel is ductile and can be formed into different shapes. Stainless steel is harder and cannot be formed easily.
Applications
Alloy steel is used in applications that need high mechanical strength. Stainless steel is required in applications like medical and kitchen utensils where corrosion resistance and aesthetic appeal are crucial.
Tensile Strength
Alloy steel has a high tensile strength, and stainless steel also has good tensile strength but not as high as alloy steel.
Fatigue Strength
Alloy steel has high fatigue strength and is suitable for making components subject to stress like springs. Stainless steel has a fatigue strength suitable for light-duty applications, but it is not as strong as alloy steel.
Impact Resistance
The impact resistance offered by alloy steel is high when it is alloyed with manganese and nickel. However, stainless steel has some grades, like austenitic, which offer good impact resistance.
Corrosion Resistance
Alloy steel doesn't offer corrosion resistance, and stainless steel is highly resistant to corrosion.
Thermal Conductivity
Alloy steel has low thermal conductivity, and hence, it is not suitable for use in high-temperature applications. Stainless steel offers excellent heat conductivity and, hence, can be subjected to high temperatures.
Chemical Composition
Alloy steel has alloying elements, such as a mixture of silicon, boron, and manganese, which makes it mechanically strong. Stainless steel has chromium in excess, followed by molybdenum and nickel, making it corrosion-resistant.
Heat Treatment Processes
Alloy steel offers compatibility with heat treatments and offers enhanced properties like toughness, hardness, and wear resistance. Stainless steel can only have some of its grades subjected to heat treatment.
The Practical Tips to Select the Right Steel for Your Project
Some tips for choosing the right steel for your project are given below.
Functional Requirements
The functional requirement of your project is also considerable when choosing material.
For instance, if you need components for marine exposure, you can choose stainless steel, whereas if you need construction-related components, alloy steel is a better choice.
Budget Constraints
Budget is also an aspect that you need to analyze when choosing the steel type for your project. Alloy steel is affordable, and stainless steel is expensive.
However, the quality also varies. Hence you need to ensure that you invest in steel that offers quality as well as falls under budget.
Aesthetic Preferences
Aesthetically, stainless steel is a very popular option. It is mostly used in interior design and architectural applications. It offers a reflective surface and a modern touch.
Maintenance and Lifespan
Stainless steel is a suitable choice when it comes to lifespan and maintenance; it is durable and needs minimal maintenance. It also offers recyclability.
Conclusion
Alloy steel and stainless steel are two very commonly adopted materials, and when it comes to choosing them for applications, make sure to choose the right option.
We at DEK offer you assistance in choosing the right type of steel and also manufacture custom components for you. So, contact us for your upcoming projects.
FAQs
Is alloy steel rust-proof?
No, alloy steel is not rust-proof; it requires additional protective coatings.
Does alloy steel break easily?
No, alloy steel offers high hardness and, hence, is not easy to break.
What are the similarities between alloy and stainless steel?
Alloy steel and stainless steel are versatile and offer high strength, which makes them suitable for various applications.
