Which of the following is an SAE Grade 5 bolt?

An SAE Grade 5 bolt is classified based on its material strength and properties. It is commonly characterized by having a tensile strength of 120,000 psi and is often used in applications where moderate strength is required. Such bolts are made from medium carbon steel and come with a specific head mark, typically consisting of three radial lines and no additional markings.

In distinguishing Grade 5 from other grades, the tensile strength is a key factor, as Grade 5 bolts are intended for tasks that experience moderate loads. They are not as strong as Grade 8 bolts, which have higher tensile strength and are used for heavy-duty applications, nor are they as low in strength as Grade 2 bolts.

Since option C is identified as the correct answer, it suggests that it represents a bolt that meets the SAE Grade 5 specifications, likely suggesting that it has the necessary properties, markings, and strength. Understanding these classifications is crucial for mechanics when selecting the appropriate fasteners for repairing or assembling machinery where strength and integrity are vital.