Nut grade analysis:
Nuts are divided into ordinary, non-standard, (old) national standard, new national standard, American system, British system, German standard, etc. according to the product attributes corresponding to different national standard numbers. Hexagon nuts are divided into three types: I type, II type and thin type according to the nominal thickness. Nuts above grade 8 are divided into two types: type I and type II.
Type I hexagon nuts are the most widely used, and type I nuts are divided into three grades: A, B, and C. Among them, grade A and grade B nuts are suitable for machines, equipment and structures with small surface roughness and high precision requirements. Class C nuts are used on machines, equipment or structures with rough surfaces and low precision requirements.
Common national standards for nuts:
GB41 Type I Hex Nut - Grade C
GB6170 Ⅰ type hexagon nut - A, B grade
GB6171 Type I Hex Nut - Fine Thread - Grade A, B
GB6172 Hexagon Thin Nuts - Grades A and B - Chamfering
GB6173 Hexagon Thin Nuts - Fine Thread - Grade A, B
GB6174 Hexagon Thin Nuts - Grade B - No Chamfer
GB6175 Ⅱ type hexagon nut - A, B grade
GB6176 Type II Hex Nut - Fine Thread - Grade A, B
GB6177 Hexagon Flange Nuts—Class A
GB55 Hexagon Thick Nut
GB56 Hexagonal Extra Thick Nut
GB1229 Big Hex Nut (High Strength for Steel Structure)
The grades of metric bolts are: 4.6; 4.8; 5.8; 6.8; 8.8; 9.8; 10.9; 12.9.
The grades of metric nuts are: 4; 5; 6; 8; 10; 12 where 4; 5 is the strength grade of the thin nut.
Nuts A; B; C grades are equivalent to the American G2; G5; G8 performance grades, and the performance grades between the two are basically the same as specified in J995!
I-type nut thread specifications are M1.6~M64, performance grades are 6; 8; 10; A2-50; A2-70; A4-50; A4-70; CU2; CU3 and AL4 grades, product grades are A and B grades , Grade A is used for specifications less than or equal to M16; Grade B is used for specifications larger than M16! (A here; B refers to the accuracy grade);
Type II nut thread specifications are M5~M36, performance grades are 9 and 12, product grades are A and B, A grade is used for specifications less than or equal to M16; B grade is used for specifications larger than M16! (here A ;B refers to the accuracy class);
Due to the high performance level requirements of type 2, the thickness of the nut is thicker, and the bolt performance grade is divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, the bolt material of grade 8.8 and above For low carbon alloy steel or medium carbon steel and heat treatment (quenching, tempering), generally known as high-strength bolts, the rest are generally known as ordinary bolts.