The performance rating of stainless steel bolts 8.8 means that the material has a tensile strength limit of 800 MPa and a yield limit of 640 MPa.
The performance grades of stainless steel bolts, studs and studs are divided into 10 grades: from 3.6 to 12.9. The number before the decimal point represents 1/100 of the tensile strength limit of the material, and the ratio of the yield limit of the representative material after the decimal point to the tensile strength limit is 10 times.
Introduction to the performance grade of stainless steel bolts
The performance rating of the nut is divided into 7 levels, from 4 to 12. The figures roughly indicate that the stainless steel nut is guaranteed to withstand 1/100 of the minimum stress.
For uniform inch thread, the external thread has three thread grades: 1A, 2A and 3A, and the internal thread has three grades: 1B, 2B and 3B, all of which are clearance fits. The higher the level number, the tighter the fit (guide: several cognitive misunderstandings of fasteners)
1, 1A and 1B grade, very loose tolerance class, which is suitable for tolerance fit of internal and external threads.
2, 2A and 2B grades are the most common thread tolerance grades specified by the Inch series of mechanical stainless steel fasteners.
3, 3A and 3B grade, screwed to form the tightest fit, suitable for tight tolerance stainless steel standard parts, for critical design of safety.
Metric thread, external thread has three thread grades: 4h, 6h and 6g, internal thread has three thread grades: 5H, 6H, 7H. The thread fit is preferably combined into H/g, H/h or G/h. For the refined fastener threads such as bolts and stainless steel nuts, the standard is recommended to use 6H/6g.
Carbon steel: The strength grade marking code consists of two parts separated by "?". The meaning of the front part of the "?" in the mark code indicates the nominal tensile strength. For example, the "4" of the 4.8 level indicates 1/100 of the nominal tensile strength of 400N/MM2. The meaning of the "?" and the numerical part after the dot in the mark code indicates the yield ratio, that is, the ratio of the nominal yield point or the nominal yield strength to the nominal tensile strength. For example, the yield point of the 4.8 grade product is 320N/mm2.
The stainless steel product strength grade mark consists of two parts separated by "-". The symbol "-" in the symbol code indicates the material. Such as: A2, A4 and other signs "-" after the strength, such as: A2-70
Carbon steel: Metric stainless steel bolt mechanical performance grade can be divided into: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9 a total of 10 performance levels.
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