Not all stainless steels are created equal. We have gone ahead to produce our own spring bars with the best quality stainless steel material. Hopefully, this article will help explain the extra steps we have taken to design something so simple, yet so important.
Three common stainless steel grades used in the watch industry are 304, 316L, and 904L - the last being used exclusively by Rolex. What makes each steel different? Why would someone use one over the other? We are here to answer these questions.
304, 316L, and 904L are austenitic steels. These steels contain 16 to 26 percent chromium and up to 35 percent nickel. These properties make them relatively resistant to corrosion. They are not hardened by heat treatment and are nonmagnetic. We will be comparing 304 and 316L stainless steels, as these are the types of steels that are most commonly used.
Have you ever noticed the '18/10' stamp on your kitchen utensils? 304 grade is the standard food grade stainless steel, which contains 18 percent chromium and 10 percent nickel. It is the most widely used stainless steel and available in a wide range of products, forms, and finishes. It has excellent forming and welding characteristics.
Corrosion resistance for 304 is generally good in a various environments and many corrosive medias. However, it is subject to pitting and crevice corrosion in warmer environments with high chloride levels. Stress corrosion cracking may occur when reaching temperatures above 60°C.
The typical applications for 304 include but are not limited to food processing equipment; kitchen benches, sinks, and appliances; architectural paneling, railings and trim; chemical containers; threaded fasteners; and springs to name a few.
Our 1.8mm Fat 304 Stainless Steel Spring Bars are a great choice for everyday use. It is not too thick and can slide though most leather and nylon straps. It is also quite resilient to stress and water.
Grade 316L, the low carbon version of 316, is the standard molybdenum-bearing austenitic grade. It ranks as the second most important stainless steel after 304. The molybdenum properties of the 316L is why it is more resistant to corrosion compared to 304. It has a particularly high resistance to pitting and crevice corrosion in chloride environments. It is often brake or roll formed, welded, soldered and cut by both thermal and mechanical methods. The austenitic structure also gives excellent toughness. 316L is usually regarded as the standard “surgical grade” or "marine grade" stainless steel.
The typical applications for 316L include but are not limited to laboratory equipment; surgical equipment; boat fittings; chemical containers; screens for mining, quarrying & water filtration; watches; and Strap Mill Canada's Extra Fat Spring Bars.
The 316L stainless steel is more resilient in a marine environments compared to 304 stainless steel. If you expose your watch in swimming pools or ocean often, the 316L SS would be the better choice - they have a better steel property and have a thicker diameter (2.0mm) to ensure it can withstand higher physical stress. With that said, it is always a good practice to inspect and replace your spring bars often to ensure they are in optimal working condition.
What are our bent spring bars for, you may ask? They are mainly to create extra clearance between your watch case and spring bar so you can slide straps through without rubbing the strap. More details in our second half of How to Change Into a Nato Strap article.
Hopefully, this answers some of the questions you may have regarding the different spring bars we offer.