Threaded Studs There Are Four Main Aspects
threaded studs There are four main aspects
Studs are made of metal, and metal corrosion methods are mainly four aspects, that is, the nature of the material itself, the use of the environment, information and environmental interface and improve the design of metal structures, if the use of complete corrosion-resistant alloy to create studs , Unless there is a special demand, otherwise in the economic concept is not real, or the appearance of the screw will produce corrosion of environmental elements completely isolated, in practice, not necessarily work, may be very difficult. Improved metal structure design can improve the impact of special circumstances in a certain situation, but most of the stud design can not be fully amended, and its maintenance role is not permanent, so this method can not basically deal with the problem, as long as the interface Anti-corrosion, that is, the appearance of anti-corrosion treatment is currently the most widely used approach.
Spindle surface corrosion treatment refers to the use of various methods in the metal surface to impose a maintenance layer, its role is to metal and corrosive environment isolation to inhibit the corrosion process, or reduce the corrosive media and metal appearance contact, and reach Avoid or reduce the purpose of corrosion.
The maintenance layer should be able to meet the following requirements:
1, corrosion resistance, wear resistance, high hardness,
2, tight structure, intact, small pores.
3, with the base metal separation strong, good adhesion.
4, the average spread and a certain thickness.
Maintenance layer is usually divided into two types of metal coating and non-metallic coating, metal coating is a strong corrosion resistance of the metal or alloy in the corrosion of metal surface constitutes a maintenance layer, this coating is also called coating. There are a lot of ways and types of metal coating, the most common of which is electroplating, followed by molten metal dip coating (hot dip plating) and chemical appearance disposal. Non-metallic coating refers to the use of organic polymer materials such as paint, and inorganic materials such as ceramics, metal equipment or parts on the appearance of the maintenance layer, the maintenance layer can be the base metal and environmental media complete isolation, to avoid the base metal corrosion due to contact In the stainless steel standard parts of the media and the formation of corrosion.
1. Normalizing: The screw is heated to the critical point AC3 or ACM above the appropriate temperature to maintain a certain time after the air cooling, pearlite-like tissue heat treatment process.
2. Annealing: Heat treatment of sub-eutectoid screws up to 20 ° C above AC3 for a period of time, cooling with the furnace slowly (or buried in sand or lime) to below 500 ° C in air.
3. Solution heat treatment: the alloy heated to high temperature single-phase temperature to maintain, so that the excess phase fully dissolved into the solid solution, and then quickly cooled to get supersaturated solid solution heat treatment process.
4. Aging: When the alloy is subjected to solution heat treatment or cold plastic deformation, it is changed at room temperature or slightly above room temperature, and its performance changes with time.
5. Solution: the alloy in a variety of phases to fully dissolve, strengthen the solid solution and improve toughness and corrosion resistance, to eliminate stress and softening, in order to continue processing and molding
6. Aging treatment: in the enhanced phase precipitation temperature heating and insulation, so that the strengthening phase precipitation, to harden, improve the strength.
7. Quenching: the austenitizing steel after the appropriate cooling rate of cooling, so that the workpiece in the cross-section within or within a certain range of martensite and other unstable structural changes in the heat treatment process.
8. Tempering: The quenched workpiece is heated to the appropriate temperature below the critical point AC1 for a certain period of time, followed by cooling with a desired method to obtain the desired heat treatment process for the organization and properties.
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Contact person: Ms. Nancy Yue