When you hear the term “18/8 stainless steel,” you might wonder what exactly it refers to and how it stacks up against other popular stainless steel grades like 304 and 316. Let’s break it down in a way that’s easy to understand, even if you’re not a metallurgy expert.
What is 18/8 Stainless Steel?
The numbers in “18/8” are shorthand for the composition of the stainless steel. Specifically, “18” refers to 18% chromium, and “8” refers to 8% nickel. This composition is what gives 18/8 stainless steel its impressive corrosion resistance and shiny appearance. But here’s the kicker—18/8 stainless steel is actually just another name for 304 stainless steel, the most common stainless steel you’ll come across.
For more information about 18/8 stainless steel, please watch the following YouTube video.
How Exactly is 18/8 Stainless Steel Made?
18/8 stainless steel is produced using an Electric Arc Furnace (EAF), where scrap metal, chromium, and nickel are melted together. The intense heat from the electric arc liquefies these materials, and precise amounts of alloying elements, like manganese and molybdenum, are added to achieve the desired composition. The molten metal is then refined to remove impurities, often using charcoal and lime, which separate impurities as slag. Once refined, the stainless steel is cast into ingots, billets, or slabs for further processing.
Properties of 18/8 Stainless Steel
18/8 stainless steel is highly valued for its excellent corrosion resistance, durability, and versatility. The following table lists its characteristics.
| Property | Value |
|---|---|
| Density | 7.9 g/cm³ (7900 kg/m³) |
| Melting Point | 1400-1450 °C (2552-2642 °F) |
| Thermal Conductivity | 16.2 W/m·K at 100 °C |
| Specific Heat Capacity | 500 J/kg·K |
| Electrical Resistivity | 0.72 µΩ·m at 20 °C |
| Modulus of Elasticity | 193 GPa |
| Poisson’s Ratio | 0.29 |
| Coefficient of Thermal Expansion | 17.2 µm/m·K (20-100 °C) |
| Tensile Strength | 515 MPa (74,700 psi) |
| Hardness | 70 HRB (Rockwell B) |
| Magnetic Properties | Non-magnetic |
18/8 Stainless Steel vs. 304
18/8 stainless steel is another name for 304 stainless steel. Both contain 18% chromium and 8% nickel, offering excellent corrosion resistance and durability. The terms are often used interchangeably, as 18/8 simply refers to the composition, while 304 is the grade designation.
18/8 Stainless Steel vs. 316
18/8 stainless steel contains 18% chromium and 8% nickel, offering good corrosion resistance for everyday use. 316 stainless steel adds 2-3% molybdenum, enhancing its resistance to chlorides and harsh environments, making it ideal for marine and chemical applications. While 316 is more durable in tough conditions, 18/8 is typically more cost-effective for general use.
18/8 vs 316 vs 304 Stainless Steel Costs
316 stainless steel is typically about 40% more expensive than 18/8 or 304 stainless steel due to its added molybdenum, enhancing corrosion resistance. In December 2023, 304 stainless steel had surcharges around $0.9229 to $0.9539 per pound, while 316 was higher at $1.3903 per pound. Scrap prices also vary, with 18/8 around $0.32 per pound and 316 at $0.60 per pound. Prices fluctuate based on market conditions and specific material needs.
18/8 vs 316 vs 304 Stainless Steel Properties
18/8 (304) and 316 stainless steels are both corrosion-resistant, but 316, with added molybdenum, offers superior corrosion resistance, especially in marine environments. 304/18/8 has a tensile strength of 540–750 MPa, while 316 has 480–621 MPa. Both have similar densities (~7.87–8.07 g/cm³) and thermal properties. 304 is more formable and slightly easier to machine, while 316 is more durable in corrosive settings. Both are non-magnetic and weldable, though 316L is preferred for welding due to its reduced susceptibility to weld decay.
Related resources: 304 vs 316 Stainless Steel
18/8 Stainless Steel vs. 18/10
18/8 stainless steel contains 8% nickel, while 18/10 stainless steel contains 10% nickel. The extra nickel in 18/10 offers better corrosion resistance and a shinier finish. Both are common in kitchenware, but 18/10 is preferred for more demanding environments due to its superior durability.
18/8 Stainless Steel vs. 18/0
In contrast, 18/0 stainless steel contains 18% chromium but no nickel, making it less resistant to corrosion and giving it a less lustrous appearance. 18/8 is more durable and commonly used in high-quality kitchenware, while 18/0 is more affordable and often used in budget-friendly options.
Is 18/8 Stainless Steel Safe?
Yes, 18/8 stainless steel is safe, it meets safety standards set by organizations like the FDA for food-grade materials. It’s non-reactive, resistant to corrosion, and commonly used in kitchenware and food processing.
What is the Yield Strength of 18/8 Stainless Steel ?
The yield strength of 18/8 stainless steel (also known as 304 stainless steel) is typically around 215 MPa (31,000 psi). This value can vary slightly based on the specific processing and heat treatment of the steel.
Is 18-8 Stainless Steel Magnetic?
18-8 stainless steel, is generally not magnetic. It is an austenitic stainless steel, which means its crystal structure typically does not exhibit magnetic properties. However, it can show slight magnetic attraction in some cases due to cold working or specific processing conditions.
Is 18/8 Stainless Steel Good?
Yes, 18/8 stainless steel is considered high-quality. It offers excellent corrosion resistance, durability, and a shiny appearance. It’s commonly used in kitchenware, appliances, and other applications where resistance to rust and staining is important.
What is Passivated 18/8 Stainless Steel?
Passivated 18/8 stainless steel has been treated with acid to enhance its corrosion resistance by forming a thicker protective chromium oxide layer.
Does 18/8 Stainless Steel Rust?
18/8 stainless steel is highly resistant to rust due to its 18% chromium content, which forms a protective oxide layer on the surface. However, it can still rust under certain conditions, such as prolonged exposure to saltwater, harsh chemicals, or if the protective layer is damaged.
Advantages and Disadvantages of 18/8 Stainless Steel
| Advantages | Disadvantages |
|---|---|
| Excellent corrosion resistance | Susceptible to chloride-induced corrosion |
| Durable and long-lasting | Not as corrosion-resistant as 316 steel |
| Non-reactive with food | Can become slightly magnetic when cold-worked |
| Easy to clean and maintain | More expensive than some lower-grade steels |
| Good formability and weldability | May not be suitable for marine environments |
Custom Stainless Steel Parts Made Easy with BOYI
Get your stainless steel parts custom-made with BOYI. We offer top-notch CNC machining services to bring your designs to life with precision and reliability. Whether you need 18/8 stainless steel or other grades, our expert team is here to deliver high-quality parts that meet your exact specifications. At BOYI, we’re committed to making the process easy and hassle-free, so you get the parts you need, exactly when you need them.
Let’s Start A New Project Today
Our engineers will contact you within 2 hours.
Conclusion
18/8 stainless steel, or 304 stainless steel, is a versatile and reliable choice for a wide range of applications. It’s durable, corrosion-resistant, and cost-effective. However, if you need enhanced corrosion resistance, especially in environments exposed to saltwater or harsh chemicals, 316 stainless steel is a better choice despite its higher cost.
More comparative information about 18/8, 304 and 316 stainless steel. Please watch the following YouTube video.
FAQ
18/8 stainless steel refers to a type of stainless steel with 18% chromium and 8% nickel. This composition provides excellent corrosion resistance and durability, making it popular for kitchenware and appliances.
18/10 stainless steel is generally better than 18/8 because it has a higher nickel content (10% vs. 8%). It’s preferred for applications where durability and a polished look are important.
The mass density of SS304 stainless steel is approximately 7.85 g/cm³ or 7850 kg/m³.
Catalog: Materials Guide
This article was written by engineers from the BOYI team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, mold manufacturing, and plastic injection molding.
