8.8 Grade

When it comes to bolts in mechanical engineering and construction, the term “8.8 grade” typically refers to a specific type of bolt. These bolts serve various purposes, including fastening steel structures together. The grading system for bolts is standardized, and “8.8 grade” denotes the following:

– The first number (8): This number represents the nominal tensile strength of the bolt material in hundreds of megapascals (MPa). For “8.8 grade” bolts, the nominal tensile strength is 800 MPa.

– The second number (8): This number represents the yield ratio or yield strength ratio of the bolt material. The yield ratio is the ratio of the yield strength to the tensile strength. For “8.8 grade” bolts, the yield ratio is 0.8, indicating the yield strength is 0.8 times the nominal tensile strength.

In summary, “8.8 grade” bolts are made from low-carbon alloy steel or medium-carbon steel and undergo heat treatment (quenching and tempering). The “8.8” indicates a nominal tensile strength of 800 MPa and a yield strength of 0.8 times the nominal tensile strength.

Using the appropriate grade of bolts is crucial in engineering applications to ensure structural integrity and safety.