The most detailed introduction of the
Bolts analysis:
A type of fastener consisting of a head and a
screw (a cylinder with an external thread) is required to be fitted with a
nut for fastening the two parts with through holes. This type of connection is called a bolted connection. If the nut is unscrewed from the
Bolt, the two parts can be separated, so the
bolt connection is a detachable connection. Because bolts are also a type of railroad accessory, railroad fittings are part of the railroad line, and the rails referred to here include rails, sleepers, joint parts, track beds, anti-climbing equipment, rail stays, and ballasts. As a holistic engineering structure, the track is laid on the roadbed and plays a guiding role in train operation, directly bearing the tremendous pressure of the rolling stock and its load. Under the power of train operation, its various components must have sufficient strength and stability to ensure that the train runs safely, smoothly and without interruption according to the specified maximum speed.
The most complete analysis of the bolt grade:
Bolts - Performance Grades Bolts for steel structure connection are rated at 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc., of which 8.8 and above are made of low carbon alloy steel or medium carbon. Steel is heat treated (quenched, tempered), commonly known as high-strength bolts, and the rest is commonly referred to as ordinary bolts. The bolt performance grade label is composed of two parts, which represent the nominal tensile strength value and the yield ratio of the bolt material. For example: Bolts with a performance class of 4.6, the meanings are: 1. The nominal tensile strength of the bolt material is 400MPa; 2. The yield ratio of the bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400×0.6=240MPa. Grade performance grade 10.9 high-strength bolts, the material can be achieved after heat treatment: 1. The nominal tensile strength of bolt material is 1000MPa; 2. The yield ratio of bolt material is 0.9; 3. The nominal yield strength of bolt material is up to The meaning of 1000×0.9=900MPa class bolt performance grade is the international standard. The bolts of the same performance grade have the same performance regardless of the difference between the material and the place of origin. Only the performance grade can be selected in the design. Strength grades The so-called 8.8 and 10.9 grades refer to the bolt's shear stress rating of 8.8GPa and 10.9GPa. 8.8 Nominal tensile strength 800N/MM2 Nominal yield strength 640N/MM2 The general bolt is expressed by "XY", X *100=The tensile strength of this bolt, X*100*(Y/10)=the yield strength of this bolt (because it is specified by the marking: yield strength/tensile strength=Y/10) The tensile strength is: 400 MPa The yield strength is: 400*8/10=320 MPa.
