High-Strength Metric Class 10.9 Steel Flanged Hex Head Screws: Choose these Class 10.9 steel screws for high-stress applications, such as valves, pumps, motors, and automotive suspension systems. They are at least 25% stronger than medium-strength steel screws. The flange distributes pressure where the screw meets the surface, eliminating the need for a separate washer. Head height includes the flange. Length is measured from under the flange.
Black-phosphate steel screws are mildly corrosion-resistant in dry environments. Zinc yellow-chromate plated steel screws resist corrosion in wet environments. Screws that meet ISO 898-1 or SAE J1199 comply with specifications and testing requirements for material quality. Screws that meet ASME B18.2.3.9M or DIN 6921 comply with specifications for dimensional standards.
Zinc-Nickel Alloy of transparent passivation: Zinc-nickel alloy plating is an excellent protective coating for use in harsh industrial atmospheres and harsh marine environments. Zinc-nickel alloy containing 7% - 9% (mass fraction) of nickel has more than 3 times the corrosion resistance of zinc plating; zinc-nickel alloy containing about 13% of nickel has more than 5 times the corrosion resistance of zinc plating and has the best corrosion resistance.
After heating at 200℃～250℃, the passivation film can still maintain good corrosion resistance. Zinc-nickel alloy has excellent characteristics such as high corrosion resistance, low hydrogen embrittlement, weldability, and machinability, and has a wide range of applications. The melting point of zinc-nickel alloy plating is relatively high (750℃～800℃), and the high-temperature resistance is good, which is suitable for use with automobile engine parts; the hydrogen embrittlement is very small, which is suitable for plating on high-strength steel and can be used as a substitute for cadmium plating, mostly for military products. A neutral salt spray test can reach out white rust time of more than 800 hours and out red rust time of more than 2000 hours.
