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 does 8.8 mean on a bolt?

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.

What do numbers on bolts mean?

In addition, most metric bolts are identified by a number stamped on the bolt head, such as 4.6, 5.8 or 10.9. The number has nothing to do with the size, but does indicate the relative strength of the bolt. The higher the number, the stronger the bolt. … A metric fastener could be designated M12 x 2, for example.

What does Grade 8 mean for a bolt?

Grade 8 – Grade 8 bolts are made from medium carbon alloy steel. The bolts of this grade feature 6 radial lines. The nominal size of the grade 8 bolts can be from 1/4″ to 1 1/2″. The minimum yield strength of this grade bolt is 130,000 psi.

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 is a Grade 10 bolt?

Class 10. This is a metric nut grading similar to the SAE grade 8 classification, which is used in conjunction with Class 10.9 bolts. This strength of nut is used in automotive, and structural industries, as well as in high temp applications.

Is there a Grade 9 bolt?

Grade 9 Bolts Grade 9 structural bolts, also known as grade 9 hex cap screws, are one the strongest structural bolts that can be used today. While the typical grade 8 bolt has a tensile strength of 150,000 PSI, a grade 9 bolt has a tensile strength of 180,000PSI.

Will Grade 5 bolts rust?

Many other grades exist but are used far less often. Grade 2, 5, and 8 are usually plated with a slightly blue-ish or yellow zinc coating, or are galvanized, to resist corrosion.

Should I use Grade 5 or 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.

What is the strongest bolt grade?

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.

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What is a grade 2 bolt?

The SAE marking standard starts with grade 2, indicated by a bolt head with no markings whatsoever. A grade 2 bolt made of low-carbon steel has a tensile strength of 64,000 pounds per square inch or less. Tensile strength is the amount of pull the bolt can withstand before breaking.

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.

What grade is a bolt with 3 markings?

Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener.

What do 3 lines on a bolt head mean?

The markings can identify the standard to which the bolt was made. For instance, if a bolt head contains three radial lines, then it’s a Grade 5 bolt. If it contains five radial lines, then the bolt is Grade 8.

What size nut fits a 8mm bolt?

SizeSpannerAllen KeyM58 mm4 mmM610 mm5 mmM813 mm6 mmM1017 mm8 mm

What does M12 mean on a bolt?

M12x1. 75 is the measurement code that indicates the thread size and thread pitch of a screw. The first half (M12), is the size measurement (metric) taken across the outside diameter of the thread (which in this case is 12mm).

Are M8 and 5/16 the same?

Well, quick answer is no. They are not the same and they are not interchangeable, although they can work under certain circumstances. The most important part is understanding the meaning of M8 and 5/16 to refer to the size of a metric screw or bolt, so then we can see why they aren’t the same thing!

Can you weld a Grade 8 bolt?

avoid welding grade 8 bolts. The grade 8 alloy is heat treatable and welding will likely seriously affect the base materials.

Is there a grade 12 bolt?

Do Grade 12 bolts exist? No SAE Grade 12 exists. On the metric side, there are no grades, only property classes. The highest strength property class is 12.9 which requires a tensile strength of approximately 1200 MPa and a yield strength of about 1080 MPa.

What steel is used for Grade 8 bolts?

Grade 8 bolts are specified for high strength applications and are commonly used in heavy manufacturing, such as tractor and truck fabrication for instance. The bolts are typically made of a medium carbon alloy steel that is plated in zinc for extra resilience.

What does a Grade 5 bolt mean?

Grade 5 Bolts and fasteners are made of medium strength carbon steel and are specified under the Society of Automotive Engineers (SAE). … These bolts are heat treated in a controlled atmosphere from 1⁄4 in. through 1-1/2 in. with a minimum tensile strength of 120,000 psi in diameters through 1 in.

What is a Grade 6 nut?

They are the most popular nut for use with metric machine screws. Class 6 nuts shall be made of a steel which conforms to the following chemical composition– Carbon: 0.50% maximum; Phosphorus: 0.060% maximum; Sulfur: 0.150% maximum.

Will a Grade 8 bolt rust?

Grade 8 Steel Bolts Grade 8 bolts have 6 evenly spaced radial lines on the head.” Unlike stainless steel, which is highly resistant to corrosion, steel, however reinforced, will oxidize over time and rust.

Are stainless bolts stronger than Grade 8?

Stainless steel bolts are rated for corrosion resistance. Bolt strength is rated in PSI (pounds per square inch). A stainless steel bolt has the same PSI rating as a grade 5 bolt (125,000 PSI). A grade 8 bolt has a stronger rating with a PSI of 150,000.

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.

What are black bolts?

The term “black bolt” is an industry term for plain finish or no finish bolts. These bolts offer no corrosion resistance and will rust over time. If you are looking for a decorative coating that is actually black, you will want to specify that they are actually coated and state which kind of coating is necessary.

What is the yellow coating on bolts?

The yellow zinc plating of the fastener refers to the colour of the chromate that is applied once the zinc has been deposited on the fixing or fastener. This chromate prevents the zinc from corroding as well as increasing overall protection.

Are galvanized bolts rust proof?

Galvanized steel is coated with a thin layer of zinc. The zinc coating protects the steel beneath it from rust. It’s used to make nuts, bolts, screws, and nails resistant to degradation when they are exposed to the weather. Galvanized steel stands up to water well — as long as it’s not salt water.

What does 12.9 mean on a bolt?

Grade and MaterialMechanical PropertiesMin. Tensile Strength (psi)Class 8.8 Medium carbon steel, quenched and tempered830Class 10.9 Alloy steel, quenched and tempered1040Class 12.9 Alloy steel, quenched and tempered1220

How can you tell if a bolt is metric?

The metric screw thread is identified by the capital letter M, followed by the nominal diameter. Metric threads are measured by the distance between two adjacent threads in millimeters (pitch). Threads on a standard (inch based) fastener are measured by counting the number of threads per inch.

How do you know if a bolt is Grade 5?

Grade 5 bolts are case hardened, meaning the bolt has been heated enough to hardened the outside of the bolt but not enough to harden the inside portion. Grade 5 bolts are identified by 3 evenly spaced radial lines on the head.