Abstract: A corrosion resistant coating and process comprises the following layers applied in sequence over a ferrous metal substrate: a micro-throwing nickel-zinc alloy plating; an optional galvanically protective zinc metal plating; a zinc-nickel alloy plating containing 5 to 30 weight percent nickel; and an organic coating such as paint. In place of the organic coating there may be utilized sequential layers of copper, nickel and chromium or chromium-substitute plating. The coating is preferably used with steel drill screw fasteners.

Abstract: A corrosion resistant coating and process comprises the following layers applied in sequence over a ferrous metal substrate: a micro-throwing nickel-zinc alloy plating; an optional galvanically protective zinc metal plating; a zinc-nickel alloy plating containing 5 to 30 weight percent nickel; and an organic coating such as paint. The coating is preferably used with steel drill screw fasteners wherein it also reduces installation torque and drill time.

Abstract: A process for making self-threading screw fasteners wherein only the cutting portions of the tip of the fasteners are hardened. The unhardened portions of the fastener remain ductile and are not subject to hydrogen embrittlement during subsequent plating to improve corrosion resistance. The process preferably comprises applying a radiation curable plastic coating over the drill tip followed by plating of a thin (minimum 0.0005 inch, 0.013 mm) layer of copper. The cured coating is then removed leaving an unplated tip. The screw is then subjected to a hardening process, wherein only the portions of the screw without the copper layer are hardened. The screw may then be plated conventionally with a corrosion resistant metal. The invention is further directed to the product of the process. A second embodiment for making screws suitable for extreme corrosion resistance is also described.

Abstract: A corrosion resistant coating and process comprises the following layers applied in sequence over a ferrous metal substrate: a micro-throwing nickel-zinc alloy plating; galvanically protective zinc metal plating; a zinc-nickel alloy plating containing 5 to 30 weight percent nickel; and an organic coating such as paint. The coating is preferably used with steel fasteners wherein it also reduces installation torque and drill time.

Abstract: A process for making self-threading screw fasteners wherein only the cutting portions of the tip of the fasteners are hardened. The unhardened portions of the fastener remain ductile and are not subject to hydrogen embrittlement during subsequent plating to improve corrosion resistance. The process preferably comprises applying a radiation curable plastic coating over the drill tip followed by plating of a thin (minimum 0.0005 inch, 0.013 mm) layer of copper. The cured coating is then removed leaving an unplated tip. The screw is then subjected to a hardening process, wherein only the portions of the screw without the copper layer are hardened. The screw may then be plated conventionally with a corrosion resistant metal. The invention is further directed to the product of the process. A second embodiment for making screws suitable for extreme corrosion resistance is also described.

Abstract: A process for making self-drilling, screw fasteners having improved corrosion resistance. The process comprises applying a frangible radiation curable plastic coating over the drill tip corrosion prior to the deposition of a heavy resistant plating on the remainder of the screw. The invention is further directed to the product of the process.

Abstract: A process for making self-drilling, screw fasteners having improved corrosion resistance. The process comprises applying a frangible radiation curable plastic coating over the drill tip corrosion prior to the deposition of a heavy resistant plating on the remainder of the screw. The disclosure is further directed to the product of the process.

Abstract: A multi-layer plating and method for improving the corrosion resistance of ferrous metal articles, such as steel fasteners, are provided in accordance with the invention. The multi-layer plating comprises, in sequence over a ferrous metal substrate, a layer of an alloy which has micro-throwing power, such as nickel-cadmium, nickel-zinc, iron-cadmium, iron-zinc, cobalt-cadmium, or cobalt-zinc, a layer of cadmium, cadmium-tin alloy, a dual layer of cadmium and tin, zinc or zinc alloy, a layer of copper, a layer of nickel, and a layer of chromium or a metallic chromium substitute. The method comprises plating, and preferably electroplating, the aforementioned layers of alloy and metals over an article having a ferrous metal substrate to obtain improved corrosion resistance.