Stainless steel may not be gold or other precious metals, but it does have its benefits when it comes to jewelry. It is corrosion-resistant therefore can do not tarnish even in high humid areas. They make exquisite long-lasting pieces that can go for long periods without discoloring.
The main worry, however, is that stainless steel is made from various groups of iron-based alloys. There could be a possibility that the alloy may contain nickel, which is known as a major allergen when it comes to jewelry. To establish this fact, we will look at, stainless steel’s composition and its different varieties in jewelry making.
What Is the Meaning Of “Nickel Free”?
Essentially the term nickel-free should mean that the metal or jewelry doesn’t contain any trace of nickel. This isn’t the case, however, because the term can be confusing. Most manufacturers use the term Nickel free to mean that there are no traces of nickel in the plating or overlay. You may still find traces of nickel in the metal alloys used as the base metals.
Additionally, most people tend to use the term hypoallergenic and nickel-free simultaneously. The two terms, however, mean different things. Hypoallergenic means that the metal or jewelry is less likely to cause an allergic reaction. It doesn’t mean that the jewelry is nickel-free. With nickel-free jewelry, on the other hand, in as much as there may be no traces of nickel, there could still be a reaction from another metal used in the piece.
What’s more, the US does not have any set laws or regulations that govern the use of the term. So, for jewelry termed nickel-free, there are still small traces of nickel allowed in the alloy. Sometimes these amounts are extremely small that you can only measure using a very sensitive instrument. It’s therefore difficult to be completely sure that a jewelry piece is completely nickel-free.
Stainless Steel Composition.
Stainless steel is a highly durable, easy to maintain metal that’s resistant to corrosion. It’s also aesthetically appealing, affordable, and readily available, which is why it’s great for making jewelry.
Generally, stainless steel is made up of mostly iron mixed with an average of 10% chromium and less than 2% of carbon and other metal elements. The presence of chromium is what gives the steel the term “Stainless”. The element is responsible for the corrosion resistance in Stainless steel. It reacts with oxygen to form an invisible protective layer that prevents the iron in the alloy from oxidizing. Hence stainless steel doesn’t stain from rust or discoloration.
To increase the corrosion resistance, other metal elements can be added to the allow. Among the common ones are nickel, manganese, titanium, molybdenum, and niobium. The highest resistant grades of stainless steel contain high levels of chromium with an addition of nickel. This type of stainless steel is known as austenitic stainless steel and is the most common type used. Other types include ferritic and martensitic stainless steel.
Stainless Steel Making Process
As mentioned, Stainless steel is made up of iron-based alloys and is a low carbon metal that’s resistant to corrosion. To make stainless steel, you have to follow a series of processes that start with melting steel and casting it to its solid form. These processes involved are as follows:
- Melting and casting– the first step is to meet all the raw materials needed for the steel in the intense heat of a furnace for 8-12 hours. Once fully melted, the molten steel is cast into semi-solid forms like tubes, squares, slabs, or rods.
- Forming – the second step involves forming processes starting with hot rolling. This is whereby heated semi-formed steel is passed through large rolls. This process ends with forming the steel into wires, sheets, plates, strips, or bars. It depends on what the semi-formed steel was. Slabs for example form the sheets and plates.
- Heat treatment– the third step involves passing the formed stainless steel through the annealing process. This is a type of heat treatment that softens the metal and reduces internal stress. Age hardening is another heat treatment technique applied to some forms of steel to increase strength. Higher aging temperature results in low strength but tougher steel, whereas, lower aging temperature results in the opposite. Both of these heating treatment techniques have to take place in a controlled setting, more so the age-hardening method. The type of heat treatment also depends on the type of stainless steel being produced.
- Descaling– during the annealing process, the steel acquires a build-up of scale, which is why the next step is to descale. There are several ways to achieve this but the most common method is pickling. This means placing the steel in a nitric hydrofluoric acid bath. Another way is by applying electric current to the steel using the electro cleaning method.
- Cutting – this step is important in getting the desired final shape and size of the steel. There are several cutting methods depending on your desired results. The fastest and cleanest way is by using flame cutting, which involves a combination of flame and iron powder. For straight cuts, you can also use guillotine knives and for circular cuts, you can use circular knives vertically or horizontally positioned. Other methods include blanking, sawing, nibbling, and plasma jet cutting.
- Finishing– the last step involves surface finishing to give the steel a more polished look that’s easier to clean. There are several methods you can employ for surface finishing. These methods include grinding, dull finishing, mirror finishing, bright finish, highly reflective finish, or buffing.
Is Stainless Steel Nickel-Free? Why?
We’ve established that the term “nickel-free” is often loosely used and doesn’t necessarily mean that there are no traces of nickel. While most people automatically assume that stainless steel is nickel-free, that is never the case.
There is a large variety of stainless steel based on their grade number. Most of the stainless steel contains some amount of nickel, an average of 8%. This includes surgical stainless steel. Two-thirds or more of the nickel produced globally goes into the processing of stainless still. So, there are higher chances that you will get a small trace or more nickel in stainless steel.
Nickel is essential in the making of steel since it helps in enhancing the corrosion resistance in the steel. It also improves its ductility and weldability as well as, reduces its brittleness. Therefore, nickel improves the durability and strength of stainless steel. The amount of nickel, however, differs from one grade of stainless steel to another.
Is Surgical Stainless-Steel Nickel-Free?
The term “surgical” is derived from the fact that this grade (316) of stainless steel is mostly used in making medical instruments used in surgery. The term is also meant to be an indication that the grade of stainless still has a high resistance to corrosion and scratches. This is thanks to the 2-3% of molybdenum present in the alloy.
It is considered to be hypoallergenic because it rarely ever reacts with people. As discussed, however, being hypoallergenic is not synonymous with being nickel-free. Surgical stainless steel does contain about 8-12% of nickel. As mentioned, nickel enhances its corrosion resistance and reduces its brittleness. It also makes the alloy non-magnetic which is a recommendation for metals used in making medical instruments.
While surgical stainless steel is largely hypoallergenic, you could still get a nickel allergic reaction. Therefore, if you have a high sensitivity to nickel, it is best to avoid any jewelry made of surgical stainless.
Is 304 Stainless Steel Nickel-Free?
304 Stainless steel is a popular grade used in a variety of areas especially in making jewelry. Its most common form is 18-8 stainless steel. This means that the composition of the steel contains 8% of nickel and 18% of chromium. That is aside from the iron, carbon, and a small percentage of other elements included in the alloy.
304 stainless steel, therefore, does contain nickel. Depending on the form, the amount of nickel could range from 8-10%. This is slightly less than surgical stainless steel, meaning you’re less likely to have a nickel reaction. The nickel, however, increases its resistance to corrosion except when exposed to chloride. It also improves its ductility which is great for making jewelry.
You’ll mostly find 304 stainless steel is used to make earring wires, necklaces, and bracelet clasps as well as pendants brooches. If you have a high sensitivity to nickel, however, it’s best to avoid this type of steel.
Is 316l Stainless Steel Nickel-Free?
316L is a type of surgical stainless steel. The only difference between grade 316 and 316L is that the latter has less carbon in its composition. That means that it’s softer compared to the 316 surgical stainless steel.
The amount of nickel in 316L surgical stainless still is however the same as the amount in 316. So is the amount of molybdenum, which also helps increase its corrosion resistance.
Despite the term nickel-free associated with stainless steel, the chance of finding traces of nickel in it are higher than not. The amounts vary based on the grade. That means you may not react to some grades of stainless steel. Still, it is advisable to be cautious and avoid stainless steel if you have a sensitivity to nickel.
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Tiger is a fashion&jewelry lover. He is also a fashion jewelry manufacturer that help thousands of small business to grow and also do business with some big fashion jewelry brands. He is a truly metal expert and he will share some information you are looking for.