Bolt grade 8.8 indicates tensile strength 800MPa, yield strength 800×0.8=640MPa, so as long as the material with yield strength greater than 640MPa can meet the requirements of 8.8. Query the material properties of the GB 8.8 bolts: the surface treatment can refer to the GB double stud galvanizing passivation.
In addition, the bolt strength is calculated according to the load you provide: according to the M8 coarse thread diameter 6.65mm, stress σ=1500×4\/π×6.652= 43.19mpa, safety factor: s=640MPa\/43.19=10.13. The safety factor is high, and cheaper carbon steel can be used: 35 steel or 45 steel quenching and tempering, which can ensure the use of requirements.