Which SAE grade bolt has the highest tensile strength?

The SAE (Society of Automotive Engineers) grading system for bolts classifies them based on their tensile strength, which is the maximum amount of tensile stress that a material can withstand while being stretched or pulled before breaking.

Among the options provided, Grade 8 bolts have the highest tensile strength. Specifically, Grade 8 bolts are made from medium carbon alloy steel and are heat-treated to achieve significant strength properties. They typically have a tensile strength of approximately 150,000 psi (pounds per square inch). This makes them suitable for high-stress applications where failure is not an option.

In contrast, Grade 5 bolts, while stronger than Grade 1 and often used in automotive applications, have a lower tensile strength, generally rated around 120,000 psi. Grade 7 bolts are not as commonly referenced in typical bolt strength discussions and are less prevalent in automotive and industrial applications, often being used for special circumstances.

Grade 1 bolts, made from low carbon steel without heat treatment, have the lowest tensile strength of the group, making them suitable for low-stress applications.

Thus, because Grade 8 bolts are engineered to handle the most demanding conditions and have the robust mechanical properties required for high-performance applications, they stand out as the option with