The meaning of common header symbols for fasteners

When we buy fasteners, we will find that there are some symbols on the header, that is, some numbers and letters. So what do these symbols mean?

①Represent the place of origin.

②Represents the tensile strength of the bolt. The grades we use daily are 4.8, 8.8, 10.9, and 12.9. 

Its grade designation consists of two parts of numbers, which represent the nominal tensile 

strength value and yield ratio of the bolt material respectively.

Generally speaking, the larger the grade of the bolt, the greater its tensile strength and yield 

strength, and the higher the strength of the bolt.

③Representing the manufacturer's Logo.

④ The A2--70 referred to represents the type of material. "A2-70" is a performance designation for screws, studs and nuts, representing the type of material. A2-70 means: A stands for austenitic stainless steel, 2 stands for 304 material, if it is A4, 4 stands for SUS316 stainless steel, the number part "70" after "-" represents the performance level of the product, and its number is the minimum resistance The tensile strength is 700N/mm2 (700MPa).