China Factory Suppliers of Round Head Torsional Shear Bolts for Steel Structures - Grade 10.9

Hexagon bolts and screws (thread diameter ≥5mm) require a convex or concave mark on the top of the head or a concave mark on the side of the head, including the performance grade and factory standard. For Carbon steel, the strength grade marking code consists of two numbers separated by “·”. The numerical part before “·” indicates 1/100 of the nominal tensile strength. For example, “4” in grade 4.8 means 1/100 of the nominal tensile strength of 400N/MM2. The digital part after the dot indicates the yield ratio (the ratio of the nominal yield point or nominal yield strength to the nominal tensile strength). For example, the yield point of grade 4.8 products is 320 N/mm2. For Stainless steel, the strength grade mark consists of two parts separated by “-”. The symbol before “-” indicates the material (e.g., A2 and A4), and the number after indicates the strength (e.g., A2-70).

Carbon steel metric bolt mechanical performance grades are divided into 10 performance grades: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, and 12.9. Stainless steel is classified into three classes: classes 60, 70, 80 (austenite); classes 50, 70, 80, 110 (martensite); and classes 45, 60 (ferrite).