Stainless Steel

Due to the fact that Damasko are well known experts on stainless steels and their metallurgical aspects, the company is often approached by watch enthusiasts and customers from all over the world. And more or less all of them ask the same questions: Which steel used for watch cases offers the highest corrosion resistance, and which one features the greatest hardness? Which company offers the best choice? Although it is possible to answer this question in one sentence, it might be of greater interest to compare the most commonly used stainless steels with each other, including one of the Damasko steels. For the Damasko watch range a highly corrosion resistant austenitic stainless steel alloy which can be fully hardened was chosen, leaving the surface with a key hardness of 1600 HV (Hardness Vickers). Just to give you an impression how hard this actually is: Titanium 180-210 HV, St. Steel AISI 316L 190-220 HV, Sapphire crystal 2000 HV. In order to compare Damasko steel with other commonly used stainless steels, Damasko choose to measure the PRE-factor (Pitting Resistance Equivalent). This can be done by defining the ratio of three important alloy components, using the following formula:

PRE = %Cr (Chromium) + 3.3 x %Mo (Molybdenum) + 30 x %N (Nitrogen)

This leads to the following results:

1. Stainless steel AISI 304 (watch cases, not in common use): PRE-factor 20
2. Stainless steel AISI 316L (commonly used for quality watches): PRE-factor 26-30
3. Stainless steel AISI 904L (marine hardware, etc.): PRE-factor 35
4. Stainless steel used for latest strategic developments of the German Navy, e.g. 1.3964/1.4566: PRE-factor 38
5. Stainless steel DIN 1.4456 (high grade alloy used for medical implants): PRE-factor 52
6. Damasko ice hardened stainless steel: PRE-factor 50-52

The above table perfectly illustrates the superior corrosion resistance of Damasko steel.

By the way: Since most quality watches are made from 316L they don’t offer real salt water resistance, so always make sure to rinse your sports/dive watch with fresh water after open water swimming or diving.