Sensitization to Corrosion of Austenitic Stainless Steels: Watch Straps Intended to Come into Direct and Prolonged Contact with Skin

Abstract

Nine grades of steel from different European steelmakers, namely 304L, 316L, and 904L, were evaluated. The austenitic steels studied are used in the manufacture of watch straps. The evaluations have been carried out in accordance with the ASTM standards which specifically concern the forms of corrosion, pitting (G48-11, FeCl3), intergranular (A262-15, Strauss method) test and Tuccillo–Nielsen test. The polarization electrochemical test on link watch straps was implemented by the microelectrode technique. Stress corrosion has also been investigated in the assembly of laser welded pin and link. It should be noted that, despite the fact that the grade of steel is in conformity with the classification standards, we note that the corrosion behavior is very different from one steelmaker to another. There are parameters that can change the quality of steel such as the technology process, casting volume, deoxidizers’ addition, remelted steel process and traces of pollutants. In consequence, we observe an extensive dispersion of results concerning nickel release, according to the EN 1811 European legislation regarding the protection of the population’s health, specifically relating to skin contact. In conclusion, steels DIN 1.4441 (316L Med) and DIN 1.4539 (904L) present a very good resistance to the morphologies of pitting and crevice corrosion. The 316L and 304L steel grades, also known as DIN 1.4435, DIN 1.4404 and DIN 1.4306, display a major difference in pitting and crevice corrosion behavior.