In different cases, according to the characteristics of the product itself and customer requirements, high-strength shackle can be galvanized, oxidized, plated Dacromet, sprayed plastic and other surface treatment.
The thickness of oxide film is mainly affected by the concentration of oxidizer and the temperature of oxidation solution. It should be adjusted carefully. The oxidation treatment time is mainly adjusted according to the carbon content of the workpiece and the oxidation requirement of the workpiece. The length of treatment time and the concentration of oxidation liquid directly affect the mechanical properties of the workpiece.
High-strength shackle with residual stress of 10.9 grade or more is easy to cause “alkali brittleness” during chemical oxidation, which results in the failure of mechanical performance of high-strength shackle. Therefore, alkali brittleness should be solved in alkaline oxidation treatment of high strength shackle. The way of surface treatment for high strength shackle is directly related to its technological process, and should be strictly carried out according to the requirements of technological documents.
When choosing plating surface treatment for high strength fasteners, it should be stipulated in technical documents and indicated that hydrogen embrittlement should be eliminated in time. When the removal of hydrogen embrittlement is incomplete or overlaps with the tempering embrittlement of heat treatment, the high strength shackle function is easily lost and the consequences are very serious. The choice of surface treatment should first be based on the characteristics of the product itself, with the fundamental principle of not affecting the high strength unloading performance.
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