Fastener Tech Data | Understanding Series Introduction
For more information, please visit yiyuan.
Many fasteners (screws, etc.), especially smaller sizes, are typically not graded&#;their strength isn't specified. Larger sizes and those for specialized purposes, though, are made to meet certain strength requirements. Inch fasteners&#;those commonly used in North America&#;will have a grade or ASTM rating. Property class (often just "class") specifies metric fasteners. Special markings on screw heads and nuts identify the fastener's grade. Replace a graded fastener with same or higher grade (don't replace a Grade 8 fastener with a Grade 5 or 2). If in doubt, ask a professional for assistance. The chart below summarizes some of the more common grades and classes available here at Fastener Mart.
Table 1. Common fastener grades and property classes. Grade/Class Strength Grade A Nuts Strength exceeds Grade 2. ASTM A325 Bolts meet ASTM A325 Type 1 standards for structural steel joints. Grade B Nuts Strength is similar to Grade 5. Grade B7 ThreadedBecause there are so many different grades and fasteners all look about the same, medium carbon and alloy steel strength grades are marked for identification. Bolts and screws also bear a mark to identify the manufacturer. If strength is important, ensure that both the grade and manufacturer identification markings are present.
Figure 1. SAE grade head marks. SAE Grade 2Screws are marked on the top of their heads, the exceptions being small (under about 1/4"), slotted and recessed head fasteners where there is insufficient room for head markings. A head with no markings is Grade 2, one with 3 lines spaced 120 degrees is Grade 5, and 6 lines spaced at 60 degree intervals is Grade 8.
Nuts are marked in several different ways&#;see Identification Marks for Hex and Heavy Hex Nuts below.
For other grade and property class specifics, look at these reference charts&#;
Be sure to visit our Fastener Tech Data section for even more information.
Fastener Tech Data | Understanding Series Introduction
Bolts are made using different materials, thread types, coatings, various classes of fit, and multiple grades. Bolt grades indicate the strength of a bolt, which is important when selecting a fastener so you can be sure the bolt is strong enough for the job.
The material used to construct the bolt and the material properties of the bolt determine the grade. Steel fasteners are commonly available in four grades that are broken into the following categories: 2, 5, 8 and 18-8 stainless (commonly referred to simply as alloy steel). Grade 8 is the hardest, Grade 5 is medium, and Grade 2 is the softest.
For more information, please visit Custom Bolt Manufacturer.
Here&#;s a quick guide to identifying bolt grades and materials, so you can be sure to match the bolt and grade to your project requirements:
Grade 2
This is the most common grade of steel fastener and is the least expensive. Grade 2 bolts have no head marking, although sometimes a manufacturer&#;s mark is present. This grade of bolt is made from low or medium carbon steel.
Grade 5
Made of medium carbon steel that is quenched and tempered for added strength, this grade is the most common bolt found in automotive applications. Grade 5 bolts have three evenly spaced radial lines on the head.
Grade 8
This grade of bolt is made of medium carbon alloy steel that has been quenched and tempered to harden it more than grade 5. They are stronger and are used in more demanding applications such as automotive suspensions. You can identify Grade 8 bolts by the six evenly spaced radial lines on the head.
Grade 18-8 Stainless (Alloy Steel)
These high strength bolts are made with a steel alloy containing an average of 18 percent chromium and 8 percent nickel, which makes them extremely strong but very brittle. They undergo additional heat treating and are typically not plated, which gives them a dull black finish. Markings can vary on these bolts.
Grades 2, 5, and 8 are usually plated with a silver or yellow zinc coating or galvanized to resist corrosion.
Graded components should be matched &#; for example, Grade 5 nuts with Grade 5 bolts &#; enabling them to work together with the same level of hardness, thereby insuring consistent strength and a better, more reliable connection.
Want more information on metal stamping clips? Feel free to contact us.