Available Gauge Sizes:
|20 gauge||18 gauge|
|16 gauge||14 gauge|
|12 gauge||10 gauge|
|8 gauge||6 gauge|
|4 gauge||2 gauge|
|0 gauge||00 gauge|
|000 gauge||1/2 inch|
|9/16 inch||5/8 inch|
|3/4 inch||7/8 inch|
|1 inch||1 1/4 inch|
We have been asked many times about the 316L & 316LVM designations for steel used in body piercing jewelry. The most common questions prople have about these designations are:
The answers to these questions are both complicated and technical in nature. A complete and best answer to them would make sense only to someone with an engineering degree or, at the very least, a strong background in metallurgy and the alloying process. Since most people do not fall in (or even remotely close to) either of these categories, we have elected to translate the answers into plain english and to present them in such a way that the average person can comprehend them. For all practical purposes, the technicalities that we will have to simplify for the sake of easy understanding are so small as to be of little or no real significance in practical applications. They are merely the types of minute details which only concern scientists, engineers, and others who thrive and dwell on the little things in life.
Lets start with a very basic background on steel in general, as it will help to understand how and why we have different "grades" of steel. Steel, in any form, does not occur naturally; it is a man-made material. Steel is made by alloying (mixing) iron with other metals to achieve greater strength and other desirable properties. The alloying process involves mixing various metals together when melted to produce a "new" metal. Depending on the recipe used, each variety of steel gets a grade designation.
For body piercing jewelry, the grade of steel we are primarilly concerned with is 316LVM ASTM F-138. This is often abbreviated to 316LVM or 316L and designates that the stainless steel is of "implant grade". So, what do all of those letters and numbers mean? Lets take a look at each element of the designation to get a better understanding of what all of it means.
The number 316 has to do with the recipe of metals used to make the steel, it basically means that it is a very high grade of steel. The L designation means that the steel is of a "low carbon" variety which is also (important for our purposes) very low in nickel content.
The VM means that the particular batch of 316L implant grade stainless steel was alloyed in a process known as "vacuum melting." The vacuum melting process reduces the chances of contamination on the surface of the batch of molten steel from the air. Although this process is statistically more likely to produce a more pure grade of 316L steel, it is neither certified as such nor a guarantee. The VM simply means that a different process was used to melt the steel. Perhaps it is easier to understand when expressed like this: 316L & 316LVM steel are really the same material and must meet the same strict standards for implant grade designation. The difference is in the process and 316LVM has a greater chance of exceeding the implant grade specifications than 316L, but it is entirely possible for a batch of 316L to be higher grade than a batch of 316LVM.
The VM increases the odds of getting a purer batch, but is not a guarantee.
The ASTM stands for the American Society of Testing & Materials. They are now known as "ASTM International" and are the body responsible for seeing that uniform standards are used throughout the world when setting specifications for various materials. The F-138 at the end means that the metal is "surgical implant grade" and meets the international requirements (including new European Union Directives) against nickel allergies.
In conclusion, aside from a variation in the manufacturing process 316L and 316LVM are indeed the same material. Although they must both met the same standards the VM designation refers to a process which may increase the purity of a batch. Both are certified to meet ASTM "implant grade" standards.