Brief introduction of stainless steel bolt performance grade

The performance level of stainless steel bolts is 8.8 refers to the tensile strength limit of the material is 800MPa, and the yield limit is 640MPa.

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 number after the decimal point represents 10 times the ratio of the yield limit of the material to the tensile strength limit.

Introduction to performance grades of stainless steel bolts

The performance level of the nut is divided into 7 levels, from 4 to 12. The number roughly represents 1/100 of the minimum stress that the stainless steel nut is guaranteed to withstand.

For unified inch threads, there are three thread levels for external threads: 1A, 2A and 3A, and three levels for internal threads: 1B, 2B and 3B, all of which are clearance fits. The higher the grade number, the tighter the fit (Guide: Several misunderstandings about fasteners)

1, 1A and 1B grades, very loose tolerance grades, which are suitable for tolerance matching of internal and external threads.

Classes 2, 2A and 2B are the most common thread tolerance grades specified for the inch series mechanical stainless steel fasteners.

Class 3, 3A and 3B, screwed to form the tightest fit, suitable for stainless steel standard parts with tight tolerances, and used for key safety designs

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 best combined into H/g, H/h or G/h. For refined fastener threads such as bolts and stainless steel nuts, the standard recommends the use of 6H/6g.

Carbon steel: The strength grade marking code consists of two numbers separated by ?. The meaning of the number before? In the mark code indicates the nominal tensile strength, such as 4 in 4.8 indicates 1/100 of the nominal tensile strength of 400N/MM2. The meaning of? In the mark code and the number part after the point indicates the yield strength 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 grade 4.8 products is 320N/mm2.

The strength grade mark of stainless steel products consists of two separate parts. The front symbol in the logo code indicates the material. Such as: A2, A4 and other signs indicate strength, such as: A2-70

Carbon steel: Metric stainless steel bolts can be divided into 10 performance levels: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9.

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