COAT PATCH SEAL
Coating Patching and Sealing
Fasteners with the natural black surface sheen, seen on Socket head cap screws and some bolts is an as forged and quenched condition. This popularly surface protector is not considered a coating and is termed Self-colour. The 'as forged' black surface treatment does not alter the part dimensionally, and retains oil on the surface of the fastener, preventing corrosion. To protect fasteners and fixings from corrosion, metallic plating processes involving a range of metal or chemical surface deposited are used and in some instances followed by an organic after coat. Hydrogen embrittlement is a real danger when electroplating high tensile fasteners, and can lead to sudden failure of the bolts or screws; care needs to be taken to avoid this.
Links to detail for coatings locking and sealing
.
.
.
.
