What do the numbers on top of bolts mean?

The higher the grade, the stronger the bolt. … English bolts have radial lines on their head to identify the grade, or strength class. The number of lines on the bolt head is 2 less than the actual grade. So, for example, a grade 5 bolt will only have 3 radial lines on its head.

What does 10.9 mean on top of a bolt?

The grade 8.8 refers to the tensile strength which is generally 116,000 psi, grade 10.9 is generally 150,000 and grade 12.9 is generally 175,000 psi.

What does 8.8 mean on a bolt head?

So, in English, a PC 8.8 bolt is a bolt with a nominal tensile strength of 800 MPa and a nominal yield strength that is 80% of the bolt’s nominal tensile strength, or 640 MPa.

Is Grade 8 or 10.9 stronger?

Class 10.9 is stronger than class 8.8. It is commonly found in high strength automotive applications. Class 10.9 is similar to grade 8. A low carbon steel for general use.

Is Grade 8 or 12.9 stronger?

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).

Table 1.

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Grade/Class Strength
Metric Class 12.9 The highest metric class for strength, it exceeds Grade 8.

What does 48 on a bolt mean?

For instance, a UTS bolt labelled #3-48 is a gauge 3 bolts or screw with 48 threads per inch, and a 1/4-20 screw has a 1/4 inch diameter and 20 threads per inch.

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 does 9.8 mean on a bolt?

A metric bolt designated as ISO class 6.8 roughly corresponds in strength to an SAE Grade 2 bolt. Bolts of ISO class 8.8 and the slightly stronger class 9.8 roughly correspond to an SAE Grade 5 bolt. An ISO Class 10.9 bolt roughly corresponds to an SAE Grade 8 bolt.

Does M8 mean 8mm?

The defined diameter of metric bolts is actually slightly larger than the actual diameter of the bolt shaft. So an M8 bolt would have a shaft diameter that’s slightly under 8mm which means that the bolt should fit through an 8mm hole.

What do letters on bolts mean?

SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener.

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Whats stronger Grade 8 or Grade 5 bolt?

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. Grade G is roughly equivalent to Grade 8.

What is a 12.9 grade bolts?

Grade 12.9 Hex Bolts are high strength bolts with 1100MPa minimum yield strength and 1220MPa minimum tensile strength. … The Grade 12.9 Material is quenched and tempered to provide hardness and strength to the bolts.

How do you tell the grade of a bolt?

You can usually figure out the grade, or strength, of a bolt by looking at the markings on its head. English bolts (U.S.S. or S.A.E) are categorized by grade, from grade 2 to grade 8, where the grade represents inch strength. The higher the grade, the stronger the bolt.

What grade are black bolts?

The colour black, referred to the fact the steel used to make the bolts was not finished with any corrosion protection, although zinc plating is a common finish for durability. The grade 4.6, relates to the strength of the bolts.

What does 10.9 hardness of nut & bolt mean?

Grade 10.9 Bolt is a high tensile bolt. These are made up of carbon steels and low boron steels. The material is heat treated by quenched and tempered methods. … The bolts are produced in a way that they have high tensile strength.