Most fastener materials are steel. As a person working in the fastener industry, it is necessary to understand the changes, differentiation and application. If it is a technician, you should have a deeper understanding. The author applies the materials I understand, refer to the relevant materials, and share with you the knowledge in this area. For those who have just engaged in the industry, we can serve as a guide. For senior people, we can further explore. Now we use the standard materials for materials. ISO (international) GB (China) DIN (Germany) AISI/SAE (United States) JIS (Japan) Some low-carbon steel fasteners with no mechanical properties or ISO Class 4.8 SAE Grade 1-2 are sufficient for Q235A SAE 1015 DIN C15. No heat treatment at all, direct cold working, and slightly higher level of fastening. For example, ISO Class 6.8 SAE Grade 3-4 should use steel with carbon content above 0.2%, such as C1020 C1022 Ml20 ML35, etc. These screws do not need any heat treatment, and the cold working strength can fully meet the requirements. In fact, the higher the carbon content, the more difficult it is for cold forming, and there is no need to use 6.8 grade screws for small materials. The special case is another matter. The most commonly used is ISO Class 8.8 SAE Grade 5 screws, generally used medium carbon steel, ML35 SAE 1035 DIN 35 JIS SWRCH35K after heat treatment (quenching + tempering), can also use SAE5140 40Cr, etc., the addition of alloying elements to heat treatment Hardenability is of great help, so the large size of the screw can choose to use alloy steel, so that the use of medium carbon steel will lead to the existence of the phenomenon of "quenching" in the center. ISO Class 9.8 10.9 SAE Grade 8 uses low to medium alloy steel materials, after heat treatment (quenching + tempering), alloy materials have a good combination of mechanical properties. The commonly used materials are 40Cr 35CrMo SAE5140 SCM435 SAE4135 SAE4137 JIS SCr440 (H) DIN 41Cr4, etc., in fact, 45# can also achieve the required mechanical properties, but in terms of comprehensive mechanical properties is slightly inferior to alloy steel. Internal thread material such as nut Flat gasket material <br> <br> without mechanical performance requirements of the flat gasket materials generally used for producing angle, such as Q235A, hardness but has a thicker sheet can be used to achieve the required hardness at the rolling is not high. Washing washers such as spring washers are generally made of 65Mn 70# or S 50CM-S 70CM and are subjected to heat treatment (quenching + tempering). Rivets, pins Rivets and pins are generally the same material as bolts, but some rivets are not too high in hardness, and some require HRB60 or less. Generally, the hardness of normalized materials is HRB70-80, so some have to be annealed to meet performance requirements. Self-tapping screws generally use C1018 C1020 C1022 and other materials, but some domestic manufacturers save money, cut corners, use 18# 15# 20# and use some manufacturers to use Q235A, then surface carburizing treatment, so self-tapping The toughness of the heart is not up to standard and easy to break. Stainless steel fasteners I don't know much, it seems that SUS304 is very common. Other special requirements for materials If the company is to use fasteners for welding, arc welding and gas welding generally have no requirements for materials. If the customer uses spot welding, it is necessary to use low carbon steel. If it is necessary to increase the strength, some low carbon materials with higher Mn content can be used. This is just a very simple example, many of which can only be noticed in actual production. When the customer specifies that a certain grade of material is to be used, and the company does not have such a material for a while, or the material is not easy to purchase on the market, you can understand the use of the fastener by the customer, and the mechanical properties can be met. Submit a written request for replacement of materials. Some purchasing customers are not very professional in fasteners, and the choice of materials is not always the best. As a manufacturer specializing in the production of fasteners, we can give better suggestions to customers and achieve double benefits. Of course, the fastener materials should pay attention to more than this. For example, the material must be out of date before use. (I used to write an article about this in the past), the surface rust material is used to make some full-thread fasteners or For fasteners that need to be ground on the surface, the material center structure and shrinkage holes are not used to make polishing head screws, etc. The application of materials is ever-changing, and it is used properly. The clear water is chicken soup. If it is used improperly, it will cause waste and increase the cost. If the company is large, the company may lose a lot of money! Single Cold Faucet,Modern Kitchen Faucets,Single Hole Kitchen Faucet,Single Handle Kitchen Faucet AIHUI Sanitary Ware , https://www.aihuisanitary.com
Bolt and other materials for external threads
ISO Class 12.9 SATM A574 is a high-strength bolt with high mechanical properties. It should be heat treated (quenched + tempered) with medium carbon alloy steel, such as SCM435 35CrMo SAE 4137 SAE4135 DIN 34CrMo4. When the surface treatment is subjected to the pickling process, hydrogen embrittlement occurs, so there must be a process of dehydrogenation (especially a fastener with sharp corners), or it will die very badly.
ISO Class 5-6 SAE Grade 3-4 is not required for mechanical properties. C1010 Q235A or C15 is generally used. It does not require heat treatment and can be cold worked. ISO Class 8, SAE Grade 5, generally use Ml35 SAE1035 DIN C35, the small size of the nut does not require heat to achieve the required mechanical properties, the specification of the large heat treatment (quenching + tempering), this point GB3098.2 Said very clearly.
ISO Class 10, SAE Grade 8 generally uses medium carbon steel to achieve its strength requirements after heat treatment. Such as SAE1035 and other medium carbon steel. One thing that everyone must pay attention to is that the nut and the bolt are different. The force is mainly based on compression rather than stretching. Therefore, the strength of the nut is not only related to the material, but also related to many factors, including accuracy, pitch, and chamfer in the nut. , nut thickness, etc.