How to choose right property class of Fastener


When I searched for some information about fastener products on the Internet, I found that many people asked some questions about how to choose fasteners Below I will share the article about the strength grade of fasteners with you.

 The strength level is divided according to the mechanical properties of bai. According to the relevant standards, the bolt performance grades are divided into more than 10 grades such as 3.6, 4.6, dao4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, among which the bolts of grade 8.8 and above are made of low-carbon alloy steel or Medium carbon steel is heat treated (quenched and tempered) and is generally called high-strength bolts, and the rest are generally called ordinary bolts.

The bolt performance grade label consists of two parts, which respectively indicate the nominal tensile strength value and the yield ratio of the bolt material. E.g:   Bolts with performance class 4.6, its meaning is:  

  • 1. The nominal tensile strength of bolt material reaches 400MPa; 
  • 2, the yield ratio of the bolt material is 0.6;  
  • 3, the nominal yield strength of the bolt material reaches 400×0.6=240MPa 

Performance grade 10.9 high-strength bolts, after heat treatment, the material can reach: 

  • 1. The nominal tensile strength of bolt material reaches 1000MPa;  
  • 2, the yield ratio of bolt material is 0.9;  
  • 3, the nominal yield strength of the bolt material reaches 1000×0.9=900MPa  

Bolts: mechanical parts, cylindrical threaded fasteners with nuts. A type of fastener consisting of a head and a screw (cylinder with external threads). It needs to be matched with a nut to fasten and connect two parts with through holes. When choosing fasteners, if there are no special requirements, I personally recommend choosing bolts with a strength of 8.8. Because I once bought a lawn mower on the Internet, and found that the hexagonal part of the bolt and the The thread is easy to wear. This caused me to disassemble and install this several times and afterwards, the bolts can no longer be used. Later, I found that the strength level of these bolts is too poor, and later replaced with 8.8, there will be no such problem.

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