Analysis Of Performance Characteristics Of Stainless Steel Bolts

Stainless steel bolts refer to a general term. In this article, stainless steel bolts include most stainless steel fastener products such as inner hexagon, outer hexagon, double-head, and nut. Because after the production of stainless steel fasteners is completed, unlike carbon steel bolts, which need later heat treatment to change its mechanical properties, after the production of stainless steel fasteners is completed, it can be used as long as the surface is cleaned, so its The performance characteristics are actually the performance characteristics of the material.

Compared with ordinary carbon steel bolts, stainless steel bolts have a better temperature application environment. However, the surface HRC Rockwell hardness of stainless steel bolts is lower than that of carbon steel bolts. The main performance of stainless steel bolts is of course not to rust, and it can not be oxidized in the exposed air environment for decades. And at very high temperatures, it can also work normally without changes in strength or torque reference. If the stainless steel bolts after production are passivated again, their high temperature resistance and corrosion resistance will be even better. perfect.

Stainless steel bolts also have a physical property called electronegative ratio. Of course, carbon steel bolts also have electronegative ratio, but the electronegative ratio of stainless steel bolts of the same specification is more than five times higher than that of carbon steel bolts. The cathode rate is related to the expansion coefficient of the bolt. Under normal circumstances, the higher the temperature of the external environment, the expansion system of the part will increase accordingly. For products with a low cathode rate, the expansion system will increase to a certain value as the temperature increases. After that, the bolts cannot be used, and the stainless steel bolts, which have a cathode rate five times that of ordinary carbon steel bolts, can keep the expansion coefficient unchanged at high temperatures, which is why it is resistant to high temperatures.

The mechanical properties of stainless steel bolts are relatively moderate. It cannot be compared with some high-strength bolts above grade 10.9, but it is not worse than bolts below grade 8.8. As long as it is not a special occasion, basically stainless steel bolts can be used. Meet the use requirements. Of course, there are also stainless steel materials with relatively high strength, such as duplex stainless steel, etc., but these materials are used to produce bolt products, the cost is too high, and the use efficiency is greatly reduced. With the development of technology, we believe that the strength of conventionally used stainless steel bolts It will also gradually improve.

It is often encountered that customers ask what is the strength grade of stainless steel bolts. Strictly speaking, stainless steel bolts are not divided into grades. If you must say how many grades it is, then 304 stainless steel bolts are equivalent to 6.8 grades, while 316 stainless steel bolts are equivalent to grade 6.8. 8.8 level, of course, this is just a simple comparison, its mechanical properties are relatively strict, and professional equipment is needed for testing.

Why do bolts of different materials have so many different mechanical properties? This is mainly because the content of alloy elements in different materials is different. After the composition of various metal elements, different material properties will be formed. For example, the carbon content in the material is a basic metal element in each material. The amount of carbon content has a great influence on the material. Usually, when the carbon content is high, the bolt strength will be high. When the carbon content is low, its strength will be relatively low, so the strength of stainless steel bolts is not as high as that of high-strength bolts, mainly due to insufficient carbon content. The various elements of the material are a kind of basic science, not to say that you can add as much as you want, but a comprehensive result. The reason why stainless steel bolts have the antirust performance that carbon steel bolts do not have is of course also related to It is related to less carbon steel content. If more carbon content is added, other changes will occur in performance.

The silicon contained in the material can strengthen the ferrite, increase the hardness of the bolt, and make the material more plastic and easy to produce. Manganese in the material can neutralize the sulfur in the material, thereby reducing the impact of sulfur on the performance of the bolt. And sulfur is insoluble in iron, which will reduce the strength and toughness of bolts. Therefore, each element will play its due role. With the development of basic material technology today, there is no such thing as adding or reducing a certain element to change the basic characteristics of the material. It must pass through each material. The impact and changes produced, and finally come to a result.