Standards and marking levels of standard parts

Qingdao standard partsThe standard difference:

New national standard: GB5780, GB5781, GB5782, GB5783

Old national standards: GB21, GB30

(1) The difference between the new standard and the old standard is: M8, M10, M12, M14, M22 series products, the difference in relative width. Except for the new M22 series, the head-to-side of new products such as M8, M10, M12, and M14 are 1MM smaller than the old products. They are 13 mm, 16 mm, 18 mm and 21 mm respectively. For the new products of the M22 series, the new standard is 2MM larger than the old standard, and the old standard is 34MM. Special attention should be paid.

Regarding the hexagon, there are two versions of the national standard, one is gb70-76, the other is 76 version

GB70-85, 85 version and standard DIN912 German standard, so you should pay attention to the difference in practice: gb70-85 and DIN912 are exactly the same, so there is no difference in the new target used. The main difference between gb70-76 and DIN912 is: M8 Series of hexagonal products, the diameter of gb70-76 round head is 12.5 mm, which is 0.77 compared to DIN912 13.27.

The difference between the new standard and the German standard is that the product specifications of M10, M12, M14, and M22 are different in the width of opposite sides. The new logo on the opposite side of the head of the M10, M12 and M14 is 1mm smaller than the German logo. The new product of M22, the width of the head is 2MM larger than the width of the DE mark, and other products can be used.

The marks and grades of standard bolts in Qingdao

Marking: Hexagon head bolts, screws (thread diameter ≥ 5mm). Use raised or recessed marks on the top of the head, or raised marks on the side of the head. Including performance levels and factory standards. Carbon steel: The code for the strength grade is "". The number consists of two separate parts. In the symbol. The meaning of the last digit is 1/100 of the nominal tensile strength (b), for example 4. The "4" of level 8 means 1/100 of the nominal tensile strength of 400N/MM2. In the symbol. The meaning of the latter digit part means the nominal yield point (S) or the nominal yield strength (0). The yield point of grade 8 products is 320N/mm2. The stainless steel product strength grade mark consists of two independent parts. The symbol "__" before the symbol indicates the material. Such as A2, A4, etc. marked with "__" intensity, such as: A2 -70 level. Carbon steel: The mechanical properties of metric bolts can be divided into: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9. 12.9 There are 10 performance levels. Stainless steel is divided into 60, 70, 80 (austenite); 50, 70, 80 110 (martensite); 45, 60 (ferrite).