Flat gasket materials, flat washers without mechanical properties are generally made of scrap materials such as Q235A, but when hardness is required but not high, they can be rolled with Q235A thick material to meet the required hardness. The function of spring washers is generally 65Mn. 70# or S50CM-S70CM manufactured by heat treatment (Note: Quenching + tempering).
Rivets and pins are generally made of the same material as the screws, but some rivets are not too rigid, and some require HRB60 or less. Generally, the normalized material hardness is HRB70-80. Therefore, some of them must be annealed to meet the performance requirements.
Self-tapping screws are generally made of materials such as C1018 C1020 C1022. However, some domestic screw manufacturers have used the Q235A with 18# 15# 20# to reduce costs by cutting corners. Then the surface is carburized to complete the work. The toughness of the heart does not meet the requirements and is easily broken.
The special screws used for welding, arc welding and gas welding generally do not require any material. If customers use spot welding, they must use low carbon steel. If they must increase the strength, they can use some low. Carbon has a higher content of Mn.
When the guest specifies that a certain grade of material is to be used, and the company does not have such material for the time being, or if the material is not easily procured on the market, it is possible to understand the purpose of the customer's special screw and to comply with the mechanical performance requirements. The guest made a written application requesting substitution of materials. Some purchasing customers are not very professional with regard to special screws, and the selection of materials may not always be the best. We specialize in producing special screws for manufacturers who can give customers better suggestions and achieve benefits. Win-win.
Of course, special screw materials should pay attention to more than this, for example, materials must be overaged before use, surface rust materials used to make some special screw thread or special screws for the surface to be polished, material center and Shrinkage holes should not be used to make polishing head screws