Glossary

A term used to describe a fastener’s material properties and strength level. Used primarily for inch fasteners, grades are defined by standards organizations such as SAE, ASTM, ISO, or IFI, and help determine appropriate applications based on tensile strength, hardness, and overall performance. Higher grades typically indicate stronger, more durable fasteners.

Symbols or numbers stamped on bolts, screws, nuts, or lock nuts that are used to easily identify the fastener’s strength level and material composition.

A common strength classification for carbon steel fasteners made from low-carbon steel. SAE J429 Grade 1 fasteners provide the lowest strength level within the SAE J429 standard and are typically used in light-duty, non-critical applications where only minimal strength is needed. Common uses include furniture assembly, light-duty brackets, automotive trim, electrical enclosures, and other non-load-bearing or temporary connections not subject to high stress or vibration. 

A common strength classification for carbon steel fasteners that are made from low to medium carbon steel. SAE Grade 2 fasteners offer a basic level of strength and are typically used in non-critical, general-purpose applications where high strength is not required.

A common strength classification for carbon steel fasteners made from medium carbon steel that are typically quenched and tempered. SAE J429 Grade 4 fasteners provide a moderate strength level under the SAE J429 standard and are commonly used in applications requiring greater strength than Grade 2 but not as high as Grade 5. These fasteners are suitable for general-purpose mechanical and structural applications where improved load capacity is needed. Common uses include automotive components, machinery parts, and light structural assemblies.

A strength classification for medium carbon steel fasteners that have undergone heat treatment to enhance their strength and durability. SAE Grade 5 fasteners provide greater strength than Grade 2 and are commonly used in automotive, industrial, and structural applications where higher load-bearing capacity is required.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.1 fasteners provide a higher strength level than Grade 5 and are intended for applications requiring enhanced mechanical performance and durability. Common uses include automotive, heavy machinery, and structural applications where improved toughness and tensile strength are necessary.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.2 fasteners offer a higher strength level than Grade 5.1 and are used in demanding applications requiring superior mechanical performance and durability. Common uses include heavy-duty automotive, industrial machinery, and structural applications where maximum toughness and tensile strength are critical.

A strength classification for alloy steel fasteners that have been heat treated to provide high tensile strength and excellent durability. SAE Grade 8 fasteners are stronger than Grade 5 and are commonly used in heavy-duty automotive, industrial, and structural applications requiring maximum load capacity and toughness.

A strength classification for alloy steel fasteners that are quenched and tempered, conforming to the SAE J429 standard. Grade 8.1 fasteners provide higher tensile strength and improved toughness compared to Grade 8, making them suitable for high-stress, heavy-duty applications. Typical uses include automotive suspension components, heavy machinery, and structural assemblies requiring superior strength.

A strength classification for alloy steel fasteners, quenched and tempered to exceed the mechanical properties of Grade 8.1 under the SAE J429 standard. Grade 8.2 fasteners are designed for extremely demanding applications where maximum strength, durability, and resistance to fatigue are required. Common applications include critical heavy machinery parts, high-performance automotive, and structural components subjected to intense stress.

A classification under the SAE J995 standard for inch-series hex nuts made from low-carbon steel. Grade 2 nuts are intended for use in light-duty, non-critical applications and are typically paired with SAE J429 Grade 1 or Grade 2 bolts. They offer low mechanical strength and usually lack grade markings.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon steel, quenched and tempered. Grade 5 nuts are intended for medium-strength applications and are typically used with SAE J429 Grade 5 bolts. They offer greater mechanical strength than Grade 2 nuts and are identified by two circumferential grade markings located 120 degrees apart, typically with one mark on the top face and the other wrapping partially around the side of the nut.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon alloy steel, quenched and tempered. Grade 8 nuts are used in high-strength applications and are typically paired with SAE J429 Grade 8 bolts. They provide the highest strength among SAE J995 grades and are identified by two circumferential grade markings located 60 degrees apart, both positioned clearly on the top face of the nut.