Bolts performance level of meaning

Steel structure connecting bolts performance are rated 3.6, 4.6, 4.8, 6.8, 8.8, 5.6, 9.8, 10.9 and 12.9 etc 10 levels, including 8.8 level and above bolts for low carbon steel material and approved by heat treatment (or medium-carbon steel quenching and tempering), generally called the high strength bolts, the rest are generally called "ordinary bolts. Bolts performance level label have two parts digital composition, seperately bolting nominal tensile strength value and generalize ratio. For example: performance level 4.6 level bolts, its meaning is: 1, bolts material nominal tensile strength of 400MPa level; 2, bolts material to generalize ratio 0.6, 3, bolts material nominal yield strength up to 400 x 0.6 = 240MPa level performance level 10.9 level high strength bolts, its material after heat treatment in can achieve: 1, bolts material nominal tensile strength of 1000MPa level; 2, bolts of material for 0.9 generalize ratio, 3, bolts material nominal yield strength up to 1000 x = 0.9 900MPa level bolt performance level is the meaning of general international standards, the same performance level of bolt, regardless of its material and origin of differentiation, its performance is the same, on the design using only performance level can. Strength grade so-called 8.8 level and 10.9 level refers to bolt shearing stress levels 880 GPa and 10.9 GPa