What Is a Corrugated Fastener?
"Stainless steel standard parts fasteners" are included. Because of their beautiful, durable, and strong corrosion resistance, stainless steel standard parts fasteners are usually used for fastening of more expensive machine parts. With the progress of society, higher requirements have been put on stainless steel standard fasteners.
Stainless steel standard fasteners
Right!
- "Stainless steel standard parts fasteners" are included. Because of their beautiful, durable, and strong corrosion resistance, stainless steel standard parts fasteners are usually used for fastening of more expensive machine parts. along with
- Stainless steel standard fasteners usually include the following 12 types of parts:
- 1. Bolt: A type of fastener consisting of a head and a screw (a cylinder with external threads), which need to cooperate with a nut to fasten two parts with through holes. This type of connection is called a bolted connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.
- Stainless steel standard fasteners have their own requirements for raw materials. Most stainless steel materials can be made into steel wires or bars for fastener production, including austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and precipitation hardening stainless steel. The selection of stainless steel materials is mainly considered from the following aspects:
- 1. Requirements on the mechanical properties of the fastener materials, especially the strength;
- 2. The requirements of working conditions on the corrosion resistance of the material;
- 3. The requirements of the working temperature on the heat resistance (high temperature strength, oxidation resistance) of the material;
- 4. Requirements on material processing performance in terms of production technology;
- 5, other aspects, such as weight, price, procurement factors must be considered.
- After a comprehensive and comprehensive consideration of these five aspects, the applicable stainless steel materials were finally selected according to the relevant national standards. The standard parts and fasteners produced should also meet the technical requirements: bolts, screws and studs (3098.3-2000), nuts (3098.15-2000), set screws (3098.16-2000).
- Table 1. Stainless steel categories and chemical composition
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- (1) Except those indicated, all are maximum values.
- (2) Sulfur can be replaced by selenium.
- (3) If the nickel content is less than 8%, the minimum content of manganese must be 5%.
- (4) When the nickel content is greater than 8%, the minimum copper content is not limited.
- (5) Molybdenum content may appear in the manufacturer's instructions, but for some applications, if it is necessary to limit the limit content of molybdenum, it must be specified by the user in the order.
- (6) Molybdenum content may appear in the manufacturer's instructions.
- (7) If the chromium content is less than 17%, the minimum nickel content should be 12%.
- (8) For austenitic stainless steel with a maximum carbon content of 0.03%, the maximum nitrogen content can reach 0.22%.
- (9) In order to stabilize the structure, the titanium content shall be 5 × C% -0.8% and shall be appropriately marked according to this table or the niobium and / or tantalum content shall be 10 × C% -1.0%. It shall be appropriately marked in accordance with this form.
- (10) For larger diameter products. In order to achieve the specified mechanical properties, in the manufacturer's instructions, there may be a higher carbon content, but it should not exceed 0.12% for austenitic steels.
- (11) The titanium content may be 5 × C% -0.8%.
- (12) The titanium content may be 10 × C% -1.0%.
- The austenitic stainless steel in Table 1 has good heat resistance, good corrosion resistance, and good weldability. Martensitic stainless steel has poor corrosion resistance, high strength and good wear resistance. Ferritic stainless steels have better upsetting properties and stronger corrosion resistance than martensite.
- The stainless steel standard parts fastener industry has roughly gone through the following 4 processes:
- 1. A large number of stainless steel standard parts enterprises have gone from extensive to new development stages after two or three decades of development. This development stage has made more stainless steel standard parts companies pay more attention to energy conservation and environmental awareness. In the new era, the majority of stainless steel standard parts enterprises are improving their management quality and can more adapt to the needs of society for development.
- 2. A large number of stainless steel screw companies have begun to move to a new stage of development. This new feature enables us to continuously integrate with the international market, develop features in economic globalization, jump out of our original region, and pay more attention to the international market. Combined with the general background of international economic development.
- 3. With the development and growth of stainless steel standard parts enterprises, some new-type, stainless steel standard parts enterprises with a certain technical content and their own advantages are increasingly showing their own development characteristics, and their strength is gradually increasing.
- Fourth, now pay more attention to technological innovation results. The practice in stainless steel standard parts enterprises, including our establishment of innovative systems, also enables more enterprises to develop and use independent intellectual property rights, so that stainless steel standard parts enterprises can achieve better development.
- Research on the technology of stainless steel fasteners anti-rust in the atmosphere.
- The vapor phase rust prevention technology of stainless steel fasteners is a green technology to prevent air pollution and its application is very fast. Development of new varieties of high-efficiency and low-toxic vapor phase inhibitors, multi-carrier application forms of vapor phase inhibitors, VCI antirust paper, VCI antirust film (VCIF), VCI anticorrugated cardboard, VCI antirust oil, VCI antirust Adhesive tape has been developed from five types to dozens and dozens of specifications. The application range has changed from the traditional anti-corrosion treatment during the storage and transportation of metal thread fasteners to the operation and maintenance of machinery and equipment and mechanical parts and anti-corrosion treatment.
- In recent years, with the increasing awareness of environmental protection and the promotion and development of various cleaner production technologies, after joining the WTO, the technical barriers to the export of threaded stainless steel fasteners in large numbers, especially foreign customers' environmental protection problems caused by the application of anti-rust grease The requirement of oil-free rust prevention has attracted the attention of the domestic fastener industry. In addition, domestic automobile manufacturers have also proposed oil-free packaging for the rust prevention of exposed oxidation, phosphating, and blackening threaded fasteners, which will accelerate the promotion of vapor phase rust prevention technology for threaded stainless steel fasteners.
- The application of vapor phase antirust technology is more widely used in the foreign fastener industry, but it is rarely used in China. The large-scale promotion has yet to be publicized. From the perspective of the use effect, its rust prevention ability has been practically recognized, and it can comprehensively improve the packaging level of threaded fasteners. With the increase in awareness of the comprehensive advantages of VCI antirust technology, the application of VCI antirust technology will be more extensive, but the cost of VCI antirust materials is slightly higher, which is also one of the main obstacles to the use of VCI technology in stainless steel fastener companies. .
- Stainless steel fasteners are also called stainless steel standard parts, which have the following standards:
- 1) Stainless steel fastener product size standards: specify the basic dimensions of the product; threaded products also include the basic size of the thread, thread end, shoulder distance, undercut and chamfer, external thread parts End dimensions and more.
- 2) Not a standard for product technical conditions. Specifically includes the following standards:
- a) Standards for fastener product tolerances: specify the content of product size tolerances and form and position tolerances.
- b) Standards for the mechanical properties of fastener products: specify the marking method of the product's mechanical performance level and the content of mechanical performance items and requirements; some fastener products change this content to product material performance or working performance Aspect.
- c) Standards for surface defects of fastener products: specify the types and specific requirements of product surface defects.
- d) Standards for surface treatment of fastener products: specify the surface treatment types and specific requirements of the product.
- e) Standards for testing stainless steel standard products: specify the content of the above various performance requirements for testing.
- 3) Standards for acceptance inspection, marking and packaging of stainless steel standard parts: specify the quality level and sampling plan of the spot inspection items during product acceptance inspection, as well as the content of product marking methods and packaging requirements.
- 4) Standards for marking methods of fastener products: specify the content of complete marking methods and simplified marking methods of products.
- 5) Standards for other aspects of stainless steel fasteners: such as standards for terms of fasteners, standards for weight of fastener products, etc.
- Stainless steel standard parts, from the production of stainless steel screw wire, stainless steel screw wire itself, wire factory when making stainless steel standard wire, all need heat treatment, so that the stainless steel standard wire to a certain hardness. Briefly introduce the heat treatment steps of the stainless steel standard production process.
- Stainless steel standard parts production process heat treatment steps
- 1. Purpose: Roll or tap the formed semi-finished product to achieve the required thread. Practically, bolts (stainless steel screws) are called rolling teeth, racks are called rolling teeth, and stainless steel nuts are called tapping.
- 2. Rolling the teeth: Rolling the teeth is to fix one dental plate and another movable dental plate to drive the product to move, and use extrusion to plastically deform the product to form the required thread.
- 3. Tapping: Tapping is to tap the formed stainless steel nut with a tap to form the required thread.
- 4. Hobbing: Hobbing is based on two corresponding screw rollers that rotate in the forward direction and use extrusion to plastically deform the product to form the required thread. Hobbing is usually used for tooth strips.
- 182. What are the heat treatment steps of stainless steel screw production process? First, heat treatment method: different heat treatment methods can be selected according to different objects and purposes.
- Quenched and tempered steel: high temperature tempering after quenching (500-650 )
- Spring steel: medium temperature tempering after quenching (420-520 )
- Carburizing steel: quenched after carburizing and then tempered at low temperature (150-250 )
- After quenching the low carbon and medium carbon (alloy) steels of stainless steel screws into martensite, as the tempering temperature increases, the general rule is that the strength decreases, while the plasticity and toughness increase. However, due to the different carbon content in low and medium carbon steels, the degree of influence of tempering temperature on them is different. So in order to obtain good comprehensive mechanical properties, the following approaches can be taken separately:
- (1) Select low-carbon (alloy) steel and temper it at a low temperature below 250 ° C after quenching to obtain low-carbon martensite. In order to improve the surface abrasion resistance of such steels, only the carbon content of each surface layer is increased, that is, surface carburization is performed, which is generally called carburizing structural steel.
- (2) Take medium-carbon steel with high carbon content, and then temper it at a high temperature (500-650 ° C) after quenching (so-called quenching and tempering), so that it can maintain sufficient strength under high plasticity conditions. This type of steel is quenched and tempered steel. If it is desired to obtain high strength, but would rather reduce plasticity and toughness, low-temperature tempering may be adopted for gold-containing quenching and tempering with low carbon content, and the so-called "ultra high strength steel" is obtained.
- (3) Steel types with carbon content between medium carbon and high carbon (such as 60, 70 steel) and some high carbon steel (such as 80, 90 steel), if used in the manufacture of springs, in order to ensure high elasticity The limit, yield limit and fatigue limit are tempered at medium temperature after quenching.
- (4) Decarburization: refers to the loss of carbon on the surface of ferrous materials (steel). After heat treatment, there will be decarburization. Slight decarburization is allowed. The depth of the decarburization layer affects the surface hardness. The deeper the decarburized layer, the smaller the surface hardness value.
- Specific testing based on GB3098.1
- Second, the operation process:
- Annealing (Pearlite Steel)
- 1. Stainless steel nut pre-heat treatment: normalized
- High temperature tempering (martensitic steel)
- (1) The purpose of normalizing is to refine the grains, reduce the degree of banding in the structure, and adjust the hardness to facilitate machining. After normalizing, the steel has equiaxed fine grains.
- 2. Quenching: The steel body is quenched by heating to about 850 ° C. The quenching medium can be selected according to the size of the steel and the hardenability of the steel. Generally, water or oil or even air quenching can be selected. Hardened steel has low plasticity and high internal stress.
- 3. Tempering:
- (1) In order to make the steel have high plasticity, toughness and appropriate strength, the steel is tempered at a high temperature of about 400-500 ° C. Steels that are more sensitive to tempering brittleness must be quickly cooled after tempering to suppress tempering Brittleness occurs.
- (2) If the stainless steel standard parts require particularly high strength, they are tempered at about 200 ° C to obtain a medium-carbon tempered martensite structure.
- (Two) spring steel:
- 1. Quenching: oil quenching at 830-870 .
- 2. Tempering: Tempering is performed at about 420-520 ° C to obtain a tempered bainite structure.
- (3) Carburizing steel:
- 1. Carburizing of stainless steel standard parts: A kind of chemical heat treatment, which refers to infiltrating the element C into the surface of the steel part in an active medium containing a certain chemical element at a certain temperature. Pre-heating (850 ) Carburizing (890 ) Diffusion (840 ) process
- 2. Quenching: Carbon and low alloy carburizing steels are generally directly quenched or once quenched.
- 3. Tempering: Tempering at low temperature to eliminate internal stress and improve the strength and toughness of the carburized layer