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                                                          STAINLESS STEEL PRODUCTS

        FASTENERS  Stainless steel is used extensively throughout industry for both original  replacing them with new ones, is more expensive than using corrosion

           equipment manufacture as well as for replacement. In cases where a joint
                                                                     resistant fasteners to begin with.  Additionally, many designers consider
                                                                     the extra cost of stainless steel fasteners as inexpensive insurance
           is designed to be taken apart and reassembled, the corrosion resistance of
           the fastener is particularly important so that corrosion will in no way
           hamper or prevent its removal. The cost of removing rusty bolts, and  against possible failure or loss of aesthetic appeal.


                                                                     The austenitic (300 series) stainless steels are characterized as having
                                                                     excellent corrosion resistance.  Chromium is the element that provides
                                                                     the stainless steel with its “stainless” name.  These specifications cover
                                                                     the 300 series stainless steels, all of which are essentially 18-8 (18%
                                                                     chromium and 8% nickel) materials, with compositions very close to  the
                                                                     nominal composition for Type 304. If an application calls for a material
                                                                     with corrosion resistant properties better than that of Type 304, Type 316
                                                                     is the next logical candidate. Type 316 stainless steel is a higher alloyed
                                                                     material containing 2-3% molybdenum, which provides pitting and
                                                                     crevice corrosion-resistant properties, especially in environments
                                                                     containing chlorides.

                                                                      Galvanic Series of Metals & Alloys

                                                                     In the process of galvanic corrosion, the combination of two  dissimilar
            Galvanic Series of Metals & Alloys + Corroded End        metals with an electrolyte is all that is needed to form a reaction. The use of
            (anodic, or increasingly active)                         dissimilar metals in structural design occurs where the fastener material is
                                                                     different from the structure being joined. The electrolyte may be present in
            Magnesium and Magnesium alloys   Monel (70Ni-30Cu)       the form of rain, dew, snow, high humidity, ocean salt spray, or even air pol-
            Zinc                        Nickel (passive)             lution. Designers and end users must take into account the reactivity of the
                                        Inconel (80Ni-13Cr-7Fe)      metals being joined.
            Aluminum 1100
            Cadmium                     304 Stainless Steel (passive)  The "Galvanic Series of Metals and Alloys" chart provides a ranking of
            Aluminum 2024-T4            316 Stainless Steel (passive)  metallic electrical potentials. The alloys near the    bottom are cathodic and
            Iron and Steel              Hastelloy Alloy C (passive)  unreactive; those at the top are most anodic. The various metals that are
                                                                     grouped together are reasonably compatible when used together; those in
            Lead                        Silver                       different groups may cause a corrosion problem. Some metals, especially
            Tin                         Titanium                     those with significant contents of nickel and chromium, are included in the
            Nickel (active)             Graphite                     table in both their active and passive conditions. Passivation, (i.e.: surface
            Inconel nickel-chromium alloy   Gold                     cleaning and sealing) lowers the metals electrical potential and improves
            (active)                    Platinum                     its corrosion behavior.
            Hastelloy Alloy C (active)
                                        -Protected End               For example, steel and aluminum are relatively compatible, but if brass and
            Brasses (Cu-Zn alloys)      (cathodic or increasingly inert)  steel contact, the steel will corrode because it is more anodic than the
            Copper                                                   brass. If brass and aluminum plates are connected by a passivated  304
            Bronzes (Cu-Zn alloys)                                   stainless steel bolt, both the brass and the aluminum will corrode severely
            Copper-nickel alloys                                     where they touch the stainless steel because they are much more anodic
                                                                     than stainless steel. The aluminum plate will corrode more heavily due to it
                                                                     being more anodic to stainless steel than brass is. The aluminum will also
                                                                     corrode where its exposed surface contacts the brass plate because brass is
                                                                     more cathodic.
           800 456-2658         email:
                                   714 Montauk Ave., Brooklyn,  NY 11208    718 434-4500   Fax: 718 434-3215
                                    60-01 55th Drive, Maspeth, NY 11378    718 786-2050   Fax: 718 228-7297
                                                     800 3rd Ave., Brooklyn, NY 11232  929 337-1821
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