You’re probably already familiar with the different stainless steel grades, from 18/8 to 18/10 to 18/0. Likely more than you can even remember.
Stainless steel is used in so many aspects of our daily lives, from the pipes that supply water for your morning coffee, to the simple teaspoon you grabbed to stir it.
It’s reliable and consistent use has given it a prominent place not only in modern manufacturing, but also modern decision-making for consumers.
To help gain a better understanding of some differences in metal grades, we can elaborate on the chemical characteristics and differences which differentiate each grade.
What is Stainless Steel?
Before identifying the three common types of steel, it is beneficial to understand why stainless steel has its unique corrosion resistant properties. Standard steel is made by adding carbon to iron. This produced a strong product, but still tended to be susceptible to rust over time.
To prevent rust corrosion, manufacturers added other metals, mostly chromium and nickel which greatly improved the ability of the steel to resist rust.
Both chromium and nickel are desirable, as they are corrosion resistant. When they are inducted into steel, they greatly enhance steel’s durability. However, both chromium and nickel are very pricey and this drives the price of the extraction the ‘mean’ variants form iron into composition to the core from the expensive process. This works for both metals.
The corrosion protection benefits of nickel and chromium and how the percentages of both nickel and chromium in steel will also allow different grades of strength to steel.
Generally, the more nickel or chromium in the steel, the greater the strength of the steel, especially than steels with only chromium. It’s logical therefore that higher nickel steel tends to be priced higher than steel with little to no nickel.
What is 18/8 Stainless Steel?
This type of stainless steel is classified as 300 series stainless steel. The most common grade is austenitic grade 304, the number denotes the grade based on its composition, which is roughly made up of 18 percent chromium, 8 percent nickel, and roughly 67 percent iron, along with a very small amount of carbon (around 0.07 percent).
Austenitic grade 304 stainless steel is unique in that it provides better corrosion resistance than other stainless steel grades. That said, its efficacy is somewhat reduced for continuous exposure to saltwater. Grade 304 stainless steel does not harden with heat treatments, which is another austenitic grade phenomenon.
One of the best attributes of grade 304 stainless steel is that it is classified as food safe, making it widely used in cookware, kitchen utensils, cutlery, polished stainless steel countertops found in many professional kitchens, etc.
We first add and estimate all the elements required to create the alloy, then combine them and melt them together, which typically takes around 8-12 hours, through an electric furnace.
Following that, we decarburize the melt, using either argon or oxygen to remove any carbon present. Once the decarbonization process is complete, the molten steel is poured into molds to cool and form the solid steel part with the desired shape and size.
What is 18/10 Stainless Steel?
The term “18/10 stainless steel” refers to its composition, namely, 18 % chromium and 10 % nickel. The nickel percentage is the only thing that is higher than the other grades; therefore, 18/10 steel has a marginally better resistance to rust and corrosion compared to some other grades of stainless.
This marginal resistance is the reason you will find 18/10 stainless steel used for flatware, cooking utensils, and other common appliances in the kitchen. The 18/10 stainless steel can also withstand higher temperatures, and you will most commonly find it being used in more demanding environments in both home and commercial kitchens.
The process for producing 18/10 stainless steel is very similar to that of producing 18/8 stainless steel. First, scrap is melted in the furnace and then decarburized. The only difference is the specific ratio of nickel to chromium, and the 18/10 just has a little more nickel in the mix.
After melting and decarburization, the steel is formed to the manufacturer’s specifications and finished using various processes depending on its intended use.
What is 18/0 Stainless Steel?
This grade deserves its own mention because it has zero nickel, as the name indicates, however it contains the same amount of chromium as the previous two grades. This grade will not be as corrosion or oxidation resistant because it does not contain nickel or molybdenum. The good thing is that these elements are costly and this grade is a lower manufacture price.
The method of manufacture is the same as the other grades where the steel is melted in a furnace and cast into the necessary shapes and sizes, except for no nickel. The steel will then typically undergo annealing or similar abilities to change its properties and finish.
Comparing All Three Steels
When choosing stainless steel, remember to examine not only the intended usage but also the environment in which it will operate. Financial limitations and the required attributes for your project will influence your decision making. Listing the limitations, advantages, and properties of various types of stainless steel are the next two tables to support your process- selection.
18/8 stainless steel
Advantages
- Has been shown to be resistant to corrosion except in sea or extreme heat conditions.
- Excellent strength.
- Can be welded easily.
- Considered to be safe with food.
Disadvantages
- May be prone to corrosion when in contact with saltwater, chlorides, strong chemicals or an acidic environment.
- It relies solely on cold working to harden, this may limit its use in applications that require only a higher strength.
18/10 stainless steel
Advantages
- It does not break down regardless of acidic or corrosive foods and liquids suggesting a tremendous resistance to breakdown.
- Easy to clean, and dishwasher safe.
- No health issues associated with food uses, so it is safe for all food uses.
- Importantly, a surface is developed to have a different attractive gloss and adapt differently compared to all other grades visually.
- Can withstand high temperatures without modification.
Disadvantages
- When compared to some other alternative grades, the time and effort required to machine this material is considerably greater.
- Its non-magnetic properties also mean that it is not always going to work best for situations where magnetic properties are integral to the application.
- It generally costs a premium due to its higher nickel content than many other metals.
- It will usually perform poorly in salt-water environments and it is therefore not the best metal for these situations.
18/0 stainless steel
Advantages
- This grade is the least expensive option available.
- Because it does not rust, it is ideal for kitchen equipment and utensils.
- Since no nickel is included in this grade, it is also ideal for items like medical devices, jewelry, and kitchen tools for individuals who are (may be) allergic or sensitive to nickel.
- Another interesting property is that it is magnetic.
Disadvantages
- Increased corrosion susceptibility: This material is at a considerably higher risk for corrosion than any other material, which is important to keep in mind in certain environments.
- Difficulty welding: When it comes to welding, the higher melting temperature and longer retention of heat can make the welding process more complicated. The added level of distortion, and the difficulty in achieving a solid bond with other materials.
- Low finish appearance: This grade of material doesn’t have as much potential for achieving a high gloss finish as some of the other grades of materials grades, which could potentially matter in applications where finish appearance is important.
- Very brittle: Without the nickel, this grade of material is substantially more brittle than other grades and will crack under load.
Property Comparison
The chart below offers a peek at the physical properties, cost, and composition of these different grades of stainless steel:
| Property | 18/8 Stainless Steel | 18/10 Stainless Steel | 18/0 Stainless Steel |
|---|---|---|---|
| Corrosion Resistance | Moderate | High | Low |
| Nickel Content | 8-10.5% | 10-14% | 0% |
| Chromium Content | 18-20% | 16-18% | 16-18% |
| strength | Good | Excellent | Moderate |
| Cost | Moderate | Higher | Lower |
| Staining Susceptibility | Moderate | Low | High |