Bolts are everywhere. They are used in commercial and industrial products, and they are found in anything from complicated machinery to basic gardening equipment. Bolts are one of the most commonly manufactured industrial fasteners. They are graded to assist people to understand how they should be used. Steel bolts come in a variety of grades. The higher the tensile strength of the steel, the more force the bolt can withstand and the tighter the fastened connection. The Society of Automotive Engineers created a technique for determining bolt strength classes; this marking method employs raised dashes on the bolt head to indicate strength. To denote bolt grade, some methods employ raised numerals on the bolt head.

How are bolts graded?

Bolts have a grading system in place to prevent them from being misused. They might become a liability if they are utilized incorrectly. When you match the task to the bolt grade, you can ensure that you get the correct sort of bolt for your project every time you buy a mechanical fastener. Furthermore, bolts are graded according to the material they are made of, their diameter, proof load, and tensile strength. Steel with a low to medium carbon content is commonly used. The tensile strength of a bolt is measured in pounds per square inch (psi), with a Grade 2 bolt having 74,000 psi and a Grade 5 bolt having 120,000 psi.

Nevertheless, here is a list of different grades of bolts:

1. ASTM Grades

ASTM International, previously the American Society for Testing and Materials, has a widely used system of bolt strength ratings. The letter A, together with three digits, is imprinted on the bolt head to denote its strength ratings. A307, which approximately equates to SAE Grade 2, is a common ASTM grade. An ASTM A325 bolt has about the same strength as an SAE Grade 5 bolt, while an A490 bolt has about the same strength as an SAE Grade 8 bolt.

2. Metric Grades

A metric bolt’s strength grade, also known as its property class, is made up of two integers separated by a dot. According to the International Standards Organization’s regulations, the property class is indicated by raised or depressed numbers on the top or side of the bolt head. The first value reflects the load necessary to break the bolt in megapascals (a Pascal unit of measurement for internal stress). The second value denotes the ratio of breaking and bending loads.

3. SAE American Grades

Grade 2 is denoted by a bolt head with no marks at all, according to the SAE marking standard. The tensile strength of a grade 2 bolt manufactured of low-carbon steel is less than 64,000 pounds per square inch. The tensile strength of a bolt refers to how much force it can bear before breaking. An SAE grade 5 bolt of tempered medium carbon steel with a tensile strength of at least 105,000 pounds per square inch has a bolt head with three raised dashes in a radial pattern. Grade 8, denoted by six elevated dashes, is the strongest commercial-quality bolt; its medium-carbon alloy steel has been quenched and tempered to reach a tensile strength of 150,000 psi.

4. A higher number means stronger

The stronger the bolt, the higher the ISO number. An ISO class 6.8 metric bolt is roughly equivalent to an SAE Grade 2 bolt in terms of strength. ISO class 8.8 and the somewhat stronger class 9.8 bolts are essentially equivalent to SAE Grade 5 bolts. An SAE Grade 8 bolt is roughly equivalent to an ISO Class 10.9 bolt.

The best option from all the imported bolts is to use the imported grade 8.8 bolts. They’re constructed of medium carbon alloy steel and feature six raised dashes on the markings. Because of the manner it was quenched and tempered, the bolt has a psi of 150,000, indicating that it can bear a lot of pressure.

Imported Grade 8.8 bolt is often referred to as the structural grade for bolts. It’s the most popular type of high-tensile steel, and it’s generally available in plain or zinc finish. It may be plated in a variety of different finishes. The tightening of high tensile steel grade 8.8 will necessitate the use of a torque wrench. These items are designed to survive and perform well under extreme conditions, and they should be clearly distinguishable from one another by a permanent marking on the head.

The Final Word

Royal Hardware is one of the best industrial suppliers that offer all kinds of industrial fasteners including but not limited to imported grade 8.8 stainless steel bolts in Pakistan, that too at the best prices available. Royal Hardware is your best choice. So go request a quote from them now!