Every year a huge number of fasteners used on all automotive companies and construction companies in Russia. The most popular metric fasteners. Metric fasteners – metal with a threaded metric cutting or mating with them kinds of metal products. Metric fasteners are bolts, nuts, washers, pins. Metric may be different step, the parameters regulated by state and international standards of GOST DIN, ISO. Metric fasteners – the most common. They are made of different materials: carbon and stainless steels of various grades and classes strength, non-ferrous metals, brass, aluminum, copper, titanium.
Also, screws, bolts, nuts can be made of polymers. As used throughout the world agreements, bolts, nuts, washers, pins are high strength, if they made of carbon steels the following property classes: 8.8, 10.9, 12.9. High-strength products can withstand the increased loads. However, carbon steels are more susceptible to corrosion, hydrogen embrittlement and fatigue weakening. Stainless steel metric fasteners manufactured from austenitic grades A1-A5.
If you compare them with high-strength, corrosion-resistant fasteners are less durable, but their corrosion resistance is much higher. Stainless steel fasteners used in wet or corrosive environments. Stainless steel hardware withstands salt, acids and oxygen. The most common fasteners parts, bolts, nuts, washers, studs are manufactured from a variety of materials to meet different needs. For example: ISO 4034 (DIN 555) Hex nut or DIN 917 Hexagon nut blank is low. While rivets (DIN 124 (ISO 1051) Rivet Round head is made only from mild steel and nonferrous metals). High-strength bolts (DIN 960 (ISO 8765), high strength bolt hexagon) nuts, and make only high grade of steel strength, making them of copper or aluminum is impossible. To create a fixture, high strength and, at the same time, resistant to aggressive media, using different coatings. Fasteners made of hardened steel cover different protective materials: metals, plastics, inorganic coatings or enamels. For the application of the metallic coating applied galvanization. In this way, the main element of the fixture is covered with zinc, chromium, nickel or brass. When coating of zinc is also used hot-dip galvanized – immersion in molten zinc details at 450-480 C based on the formation of coating steel with zinc good wetting. This method has significant disadvantage. It is impossible to withstand the coating thickness due to sag, which can be formed in some areas. Hot way can not be used to cover the product if you want to just survive in their size and cases where high temperatures can change the properties of the product. The plating method is superior to zinc deposition. When electroplated metal saving comes in comparison with thermal way up to 50%. Increased chemical resistance is ensured because of the high purity of the deposited metal. Examples of inorganic coatings are mainly used phosphate films formed on the surface of steel products.