Quality Inspection for Thin Nuts And Bolts - Factory Manufacture Various Bolt Truck Parts Round Head Torsional Shear Bolts –

Factory Manufacture Various Bolt Truck Parts Round Head Torsional Shear Bolts

Bolt marks and performance grades
(1) Logo. Hexagon bolts and screws (thread diameter ≥5mm). A convex or concave mark on the top of the head or a concave mark on the side of the head is required. Including performance grade, factory standard. Carbon steel: Strength grade marking code consists of two numbers separated by “·”. The numerical part before “·” in the marking code indicates the nominal tensile strength. For example, “4″ in grade 4.8 means 1/100 of the nominal tensile strength of 400N/MM2. The meaning of “·” and the digital part after the dot in the marking 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 grade 4.8 products is 320 N/mm2. Stainless steel product strength grade mark is composed of two parts separated by “-”. The symbol before “-” indicates the material. For example, A2 and A4 indicate the strength after a -, for example, A2-70

(2) Grade. Carbon steel: Metric 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 grades. Stainless steel is divided into 60,70,80(austenite); 50,70,80,110(martensite); 45,60 (ferrite) class iii.