How do you determine the grade of a allen head bolt?

How can you tell just by looking at a screw what grade it is? In addition to the head of the screw carrying the manufacturer’s symbol, a grade tow has no other markings, a grade five has three equidistant lines radiating out from the center, and a grade eight has six equidistant lines radiating out.

How do I know what grade my Allen bolts are?

Hex bolt grade refers to the grade of steel used in manufacturing the screw. This determines the amount of stress that can be applied to the fastener, known as “tensile strength.” The grade of a hex cap screw can be identified by markings on the head of the screw.

What grade are Allen head cap screws?

Socket cap screws are often available in grade 12.9, meaning it has a UTS of 1200 MPa and will yield at 90% of this (1080 MPa).

What grade is a hex bolt?

Hex bolts (six sided heads) are the industry standard for fasteners with forged heads. ASTM A307 grade A bolts, all SAE hex bolts, and several other common specifications require a standard (finished) hex head.

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Is grade A the same as Grade 5?

Because there are so many different grades and fasteners all look about the same, medium carbon and alloy steel strength grades are marked for identification.

Table 1.

Grade/Class Strength
Grade 2 Low strength.
Grade 2H Nuts Strength is similar to Grade 5. Use with ASTM A325 structural bolts.
Grade 5 Medium strength.

Is Grade 8 the strongest bolt?

Commercial-grade 8 bolts are the strongest option available. They’re made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.

What is the difference between Grade 2 and Grade 5 bolts?

Grade 2 is a standard hardware grade steel. This is the most common grade of steel fastener and is the least expensive. Except a possible manufacturer’s mark,Grade 2 bolts have no head marking. Grade 5 bolts are hardened to increase strength and are the most common bolts found in automotive applications.

How do you determine the grade of a socket head cap screw?

Socket head cap screws are not grade designated as are hex head cap screws. A standard inch series socket head cap screw is 20% stronger than a Grade 8 hex head cap screw and 50% stronger than a Grade 5 hex cap screw.

What is meant by 8.8 grade bolt?

In the case of a 8.8 grade bolt the first figure signifies that the Tensile Strength is at least 800MPa. The second figure signifies that the fastener will begin to yield at 80% of the Ultimate Tensile Strength, i.e. at least 640MPa.

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What is a Grade 5 bolt?

Grade 5 Bolts and fasteners are made of medium strength carbon steel and are specified under the Society of Automotive Engineers (SAE). If your application calls for heavier materials, you may need Grade 8 Bolts because they are the hardest and are often used in heavy manufacturing applications.

What is a Grade 5 hex bolt?

Grade 5 heavy hex bolts are externally threaded fasteners made of carbon steel. … These bolts are fully threaded or partially threaded depending on the length with a six sided, hexagonal head. The ASME standard covers hex bolt dimensional specifications designated by ASME B18.

What is the difference between Grade 5 and Grade 8 bolts?

Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head.

What do bolt grades mean?

The grade of a bolt determines the maximum amount of stress (tensile strength) that the bolt can handle. Tensile strength is the amount of pull the bolt can withstand before breaking. … The SAE marking system uses raised dashes on the bolt head to indicate strength.

How do I identify a bolt?

Fasteners are identified by four or five attributes; Type, Material, Diameter, Length, and Thread Pitch or Count (machine thread fasteners only).

Are all Grade 5 bolts the same?

Grade 5 bolts range from ¼” to 1 and ½” in diameter. A different classification is necessary for bolts larger than 1 and ½”. When completed, a manufacture Grade 5 bolt is a finished hex bolt with nuts that also feature a pattern that is finished hex.

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What strength is a Grade 5 bolt?

Bolt Grade Markings and Strength Chart

Head Marking Grade and Material Mechanical Properties
Min. Tensile Strength (psi)
No Markings Grade 2 Low or medium carbon steel 74,000
3 Radial Lines Grade 5 Medium carbon steel, quenched and tempered 120,000