As we all know, the strength of austenitic stainless steel 304 grade 316 fasteners is distinguished by 70 or 80 grades (such as A2-70, A4-70 or A2-80,A4-80), many people

Will ask what grade is equivalent to carbon steel fastener? According to the requirements of GB3098.1-2000 standard, the tensile strength of austenitic stainless steel fasteners at grade 70 is between the strength of carbon steel

Between grades 6.8 and 8.8, grade 80 approximates the 8.8 strength of carbon steel and can be replaced accordingly if conditions permit.

The performance grade of the bolt 8.8 refers to the tensile strength limit of the material 800MPa and the yield limit of 640MPa.

The performance grades of bolts, studs and studs are divided into 10 grades: from 3.6 to 12.9. The number in front of the decimal point represents 1/100 of the material's tensile strength limit, and the number behind the decimal point represents 10 times the ratio of the material's yield limit to its tensile strength limit.

The performance rating of nuts is divided into 7 grades, from 4 to 12. The figure roughly represents 1/100 of the minimum stress that the stainless steel nut is guaranteed to withstand.

For the unified inch thread, there are three grades of the external thread: 1A, 2A and 3A, and three grades of the internal thread: 1B, 2B and 3B, all of which are clearance fits. The higher the grade number, the tighter the fit.

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

Class 2, 2A and 2B are the most common thread tolerance classes specified in the British series of mechanical stainless steel fasteners.

Grade 3, 3A and 3B, screw together to form the tightest fit, suitable for tight tolerance stainless steel standard parts for safety-critical designs.

For metric threads, there are three thread grades for external threads: 4h, 6h and 6g, and three thread grades for internal threads: 5H, 6H and 7H. Thread fit is best combined into H/g, H/h or G/h, for bolts, stainless steel nuts and other refined fastener threads, the standard recommends 6H/6g fit.

Carbon steel: Strength grade marking code by "?" Consists of two separate digits. Mark "? "in code The meaning of the former number part indicates the nominal tensile strength, such as the 4.8 level "4" indicates the nominal tensile strength of 400N/MM2 1/100. Mark "? "in code The meaning of the digit part after the and point 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 Class 4.8 products is 320N/mm2.

The stainless steel product strength grade mark is composed of two parts separated by "-". The symbol before "-" in the marking code indicates the material. Such as: A2, A4 and other signs "-" after the intensity, such as: A2-70.

Carbon steel: metric bolt mechanical performance grades 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 grades.