Grade 8 Square Head Bolt

（1）Product Definition

Grade 8 square head bolt is a high-strength fastener with a square head and a performance level meeting the SAE J429 Grade 8 standard. The square head design provides four 90° contact planes for the wrench, enabling quick engagement in harsh working environments and effectively avoiding the "slip angle" problem commonly encountered by traditional hexagonal heads in dirty environments.

（2）Key specification parameters

Take the product specification Grade 8 square head bolt as an example, the core size parameters are as follows:

（3）Mechanical properties

Application fields

Grade 8 square head bolt features high strength, excellent vibration resistance performance and a unique anti-torsion design. It is widely used in the following fields:

（1）Heavy machinery and mining equipment: The square-head design still maintains effective engagement even in oily and muddy environments, and is particularly suitable for harsh conditions.

（2）Railway tracks and switches: Used for fixing the steel rail clamps, switches and sleepers.

（3）Agricultural machinery: Widely installed in key components such as the transmission system of tractors and the cutting blades.

（4）Construction engineering and heavy machinery manufacturing: Suitable for heavy-duty applications such as steel structure connections and large equipment base fixation.

（5）Maintenance of old equipment and restoration of vintage buildings: In the restoration of traditional industrial equipment and antique buildings, many old-style machines have standard configurations.

FAQ

（1）What is the material of Grade 8 square head bolt?

We use medium carbon alloy steel (such as 4140, 4135 or 40Cr), which is quenched and then tempered. It is produced strictly in accordance with the SAE J429 Grade 8 standard.

（2）What size ranges can you offer? Is there any stock available?

The common specifications range from 1/4" to 1" in diameter, and lengths from 3/4" to 10" are all in stock. Larger sizes (above 1-1/8") can be custom-made. The standard parts are well stocked and can be shipped on the same day or within 3 working days.

（3）Could you provide the salt spray test report?

Yes, we can. According to your request, we can conduct neutral salt spray tests (NSS) on each batch of products and provide the test report.

（4）Is special tool required during installation?

No. Ordinary open-end wrench, adjustable wrench and star wrench can all be used.

（5）What quality certifications does your factory have?

We have obtained ISO 9001:2015 quality management system certification and can provide performance reports that meet SAE J429 requirements.