Stainless steel bolts refer to fasteners made of stainless steel with spiral grooves. The strength level of stainless steel bolts determines their range of use and load-bearing capacity. The following is a detailed introduction to the strength grades of stainless steel bolts for your reference.
1、 Strength grade of stainless steel bolts
The performance levels of stainless steel bolts are usually represented by numbers and divided into three levels: 8.8, 10.9, and 12.9. The 8 in front of the number represents the tensile strength limit of the material at 800MPa, 10 represents the tensile strength limit of the material at 1000MPa, and 12 represents the tensile strength limit of the material at 1200MPa. The decimals such as. 8 and. 9 after the number represent 10 times the ratio of the yield limit to the tensile strength limit of the material.
2、 Performance levels of stainless steel bolts, studs, and nuts
The performance levels of stainless steel bolts, studs, and nuts are divided into 10 levels from 3.6 to 12.9. The number in front represents 1/100 of the tensile strength limit of the material, while the number behind represents 10 times the yield ratio of the material.
3、 Performance levels of stainless steel nuts
The performance level of stainless steel nuts is divided into 7 levels, from 4 to 12. The number roughly represents 1/100 of the minimum stress that the nut can withstand.
4、 Stainless steel thread grade
For Unified Inch threads, external threads are divided into three grades: 1A, 2A, and 3A, and internal threads are divided into three grades: 1B, 2B, and 3B. The higher the level number, the tighter the fit.
1. 1A and 1B are very loose tolerance levels, suitable for tolerance fits of internal and external threads.
2. Class 2A and 2B are the most common thread tolerance levels specified for inch series mechanical stainless steel fasteners.
3. The 3A and 3B grades form the tightest fit and are often used for stainless steel standard parts with tight tolerances, as well as safety requirements for critical designs.
For metric threads, external threads are divided into three grades: 4h, 6h, and 6g, while internal threads are divided into three grades: 5H, 6H, and 7H. The best thread fit is when combined into H/g, H/h, or G/h. For precision fasteners such as bolts and stainless steel nuts, the standard usually recommends a 6H/6g fit.
5、 Strength grade markings for carbon steel and stainless steel
The strength grade marking of carbon steel products consists of two parts of numbers. The meaning of the number before "?" in the symbol code represents the tensile strength, for example, "4" in level 4.8 represents 1/100 of the nominal tensile strength of 400N/MM2, and the number after "?" in the symbol code represents the yield ratio, which is the nominal yield point or the ratio of nominal yield strength to nominal tensile strength.
The strength grade mark of stainless steel products consists of two parts separated by "-", where the symbol before "-" represents the material, such as A2, A4, etc., representing different stainless steel materials. The following numbers indicate its strength level, such as A2-70 or A4-80.
6、 Summary
The strength grades of stainless steel bolts, stainless steel thread grades, carbon steel, and stainless steel are respectively composed of numbers and symbols. Different numbers and symbols represent different technical indicators and standards. Engineers should choose appropriate stainless steel bolts based on actual needs to ensure engineering quality and safety.
