Grade 4.8 bolts
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Dear teachers: HG20592-20635 mentions hex head bolts of grades 5.6 and 8.8. Why isn’t the 4.8-grade bolt mentioned, in situations where 8.8-grade hex head bolts cannot be used? Is level 4.8 also unusable?
Grade 4.8 and Grade 8.8 refer to the performance grades of bolts; they have nothing to do with the material of the bolts. The definition of grade 4.8 is as follows: the “4” represents 4*100=400 MPa, which is the tensile strength of the bolt. The “0.8” denotes the yield ratio; thus, the nominal yield strength is 400×0.8=320 MPa. The properties of an 8.8-grade bolt are as follows: tensile strength = 800 MPa, yield strength = 800 * 0.8 = 640 MPa. In places where even 8.8-grade high-strength bolts fail to meet the requirements, 4.8-grade bolts definitely cannot be used. The performance speaks for itself.
Which specification mentions Grade 4.8 bolts?