Introduction to stainless steel screws
Stainless steel screw selection principle:
The choice of stainless steel materials is mainly considered from the following five aspects;
1. Requirements for mechanical properties, especially strength, of stainless steel screw materials;
2. Requirements for the corrosion resistance of materials under working conditions;
3. The requirements of the working temperature on the heat resistance (high temperature strength and oxidation resistance) of the material;
4. Requirements for material processing performance in terms of production process;
5, other aspects, such as weight, price, procurement and many other factors must be considered.
Application field
Stainless steel screws are widely used in machinery, petrochemical, telecommunications, chemical, construction, power, textile, sports equipment, paper, sewage, shipbuilding, automotive and other industries. With the improvement of domestic economic living standards, the application range of stainless steel screws will be more widely.
Mechanical behavior
Stainless steel screws, as the name suggests, must be made of stainless steel screws and wire rods. The performance of stainless steel screws is mostly related to stainless steel. Consider the performance and organization of stainless steel, and understand the performance of stainless steel. Therefore, it is understood that stainless steel has good mechanical properties such as rust resistance, corrosion resistance, high temperature resistance, etc., and stainless steel screws certainly have these good mechanical properties. As stainless steel materials become more and more excellent. The mechanical properties of stainless steel screws produced by the screw industry are getting better and better. Anti-rust, anti-corrosion ability, and high temperature and high pressure is getting stronger.
Physical properties
Comparing the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferrite and martensitic stainless steel, and slightly lower than that of austenitic stainless steel; the resistivity is carbon steel, ferrite type, martensite type and The order of austenitic stainless steel is increasing; the order of linear expansion coefficient is similar, the austenitic stainless steel is the highest and the carbon steel is the smallest; the carbon steel, ferritic and martensitic stainless steel are magnetic, and the austenitic stainless steel is non-magnetic. However, when cold working hardening forms a phase transformation, magnetism will be generated, and the martensite structure can be removed by heat treatment to restore its non-magnetic property. Compared with carbon steel, austenitic stainless steel has the following characteristics:
1, high electricity rate, about 5 times that of carbon steel;
2, the large coefficient of linear expansion, 40% larger than carbon steel, and with the increase of temperature, the coefficient of linear expansion coefficient of stainless steel screws is correspondingly increased;
3. Low thermal conductivity, about 1/3 of carbon steel.
Heat resistance
Heat resistance refers to the performance of oxidation resistance or resistance to gas medium corrosion, that is, thermal stability, and sufficient strength, that is, heat strength at high temperatures.
As the material requirements of the products produced by the customers are getting higher and higher, the requirements for the screws used in the materials of the products are getting higher and higher. In the face of harsh environments and special occasions, the quality of stainless steel screws is increasingly used. The stainless steel screws were thus selected. The requirements are getting higher and higher, and the material of stainless steel screws is getting higher and higher. Therefore, many of the ordinary stainless steel screws SUS201 are replaced by stainless steel SUS304 screws and stainless steel screws SUS316. Of course, some requirements are not so high, the average customer will choose the stainless steel screw SUS201 which is relatively cheaper.
Analysis of the cause of the fracture
Sometimes, the iron screws are often broken, and sometimes the stainless steel screws are broken. But in general stainless steel screws are rarely broken. Because the stainless steel screw wire itself is harder. However, in certain cases, the stainless steel screws will still break. So what are the main reasons for the broken stainless steel screws?
The reason why the stainless steel screw is broken is as follows:
1. The quality of raw materials used in stainless steel screws, stainless steel screw wire quality is not good. There are a lot of impurities, impure, resulting in insufficient hardness of stainless steel screws;
2. The problem of producing stainless steel screws. For example, the stainless steel screws with eccentricity of the head, and the Q value is too deep and the R position is too small when the undercut operation is performed during manufacturing;
3. When the customer uses stainless steel screws, the force is too large. Generally, you can do a lower torque test to see what the minimum breaking force is, and then adjust the torque;
Of course, the stainless steel screw breaks definitely more than the above three reasons. But the above three reasons are the main reason for the breakage of stainless steel screws. When the stainless steel screw is found to be broken, it can be checked step by step. See what causes it.