As dictated by the industry standards, a grade 8 bolt will have six lines stamped into the head that point towards its center. The metric equivalent of the lines is the number 10.9. If the bolt you're trying to identify is old and rusted, then there's a chance you can't read the markings.
Full Answer
What is a Grade 8 bolt?
Grade 8 bolts refer to grade 8 high strength bolts, which are generally defined as grade 8.8 bolts. The first number represents 1 / 100 of the tensile strength, and the second number represents 10 times the ratio of yield to tensile strength.
How do I identify the grades of bolts?
This chart helps to identify the grades of bolts using the identification marks on the bolt's head along with the strength and hardness of common grade bolts. Please note the bolt heads may also include the manufacturer's identification stamp, especially with high strength bolts.
What is the strength of a high strength bolt?
From the strength level: high strength bolts are widely used. 8 s and 10.9 s are commonly used, of which 10.9 is the most. The strength grade of common bolts is lower, generally 4.4, 4.8, 5.6, and 8.8. 8.8 Class bolts are high-strength bolts, and the main surface treatment is zinc plating, yellow plating, black, or hot-dip galvanizing.
What is the difference between Grade 8 screws and Grade 8 nuts?
So according to our usage habits, the performance grade of Grade 8 nut is wider than that of grade 8.8 screw, and the lower hardness down (i.e. lower limit of 8.8) and upward hardness is slightly higher (upper limit of grade 8.8).
Is Grade 8 steel corrosion resistant?
Grade 2, 5, and 8 are usually plated with a slightly blue-ish or yellow zinc coating, or are galvanized, to resist corrosion.
Are Grade 8 bolts galvanized?
Each grade-8 bolt features a steel construction with a galvanized finish for added strength. For use with grade-8 nuts.
What is a grade 8 bolt good for?
Grade 8 bolts have the highest ratings with tensile strength of 150,000 psi. Grade 8 bolts are used marine, military, aerospace, off-road vehicle markets and related mechanical applications where stress and strong load bearing pressure is required.
Are Grade 8 bolts zinc plated?
The grade 8 steel hex bolt has a zinc yellow-chromate plated finish and an external hex drive, and meets American Society of Mechanical Engineers ASME B18.
Is stainless steel stronger than Grade 8?
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.
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 bolt is stronger than Grade 8?
Grade 9 bolts are ideal for heavy-duty applications and are also often used in heavy machinery such as bulldozers. Not only are these bolts considerably stronger than they're grade 8 counterparts, but they are also considerably more resistant to corrosive elements as they are made with yellow zinc chromate.
How can you tell if a bolt is grade 8?
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. A grade 8 bolt will have 6 radial lines on its head.
Are Grade 8 bolts the strongest?
The strongest commercial-quality bolt is grade 8, marked by six raised dashes; its medium-carbon alloy steel has been quenched and tempered to achieve a tensile strength of 150,000 psi.
Are Grade 8 bolts coated?
Grade 2, 5, and 8 are usually plated with a slightly blue-ish or yellow zinc coating, or are galvanized, to resist corrosion. Bolts are typically marked on the head to show what grade bolt they are. Note that, in addition to the grade marking, many bolts also have a manufacturer's mark.
What grade are Home Depot zinc bolts?
Grade 8Zinc-Plated Grade 8 Hex Bolt 810148 - The Home Depot.
Are zinc bolts rust proof?
All zinc galvanized coatings are more corrosion resistant than bare iron or steel. Like all ferrous metals, zinc corrodes when exposed to air and water. However, zinc corrodes at a rate of 1/30 of that for steel. Also like other ferrous metals, zinc corrodes or rusts at different rates depending on its environment (8).
What is a grade 8 bolt made of?
medium carbon alloy steelGrade 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.
Are grade 8.8 bolts Galvanised?
Can high strength bolts be galvanised? General grade high strength bolts (ISO grade 8.8) to BS 4395 Part 1, (equivalent to ASTM A325) can be galvanized without difficulty.
What type of steel is Grade 8?
medium carbon alloy steelGrade 8 (SAE J429) is a medium carbon alloy steel with one of the highest tensile strengths available. With a minimum tensile strength of 150 ksi and a minimum yield of 130 ksi, Grade 8 has a higher tensile and yield strength than other steel grades such as Grade 5 and B7.
What is a Type 8 bolt?
A grade 8 bolt is stronger than the more commonly used grade 5. It is made of alloy steel and has six radial lines on the top of the bolt head. Grade 8 bolts have a tensile strength of 150,000 pounds per square inch.
What is plating metal?
The plating is a zinc electroplate with a gold irridite finish. zinc can be finished raw (silver), black (actually sort of dark green) or gold. If the plating is done well over clean metal if will be very corrosion resistant.
Is it OK to use coated fasteners?
I'd consider it just OK, but a better alternative is to invest in higher quality coated fasteners.
Do zinc coated bolts hold up?
I Had a lot of zinc coated bolts on my off-road truck,they hold up good. I think on some thing that might see a little rain and thats,it they will be fine.IMO
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 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.
Which is stronger Grade 8 or Grade 10 bolt?
No matter the system used to grade the bolts, the higher number means the stronger the bolt. For most home and automotive applications, you won’t need anything more than a grade 8 bolt strength or metric class 10.9.
Are stainless bolts stronger than Grade 8?
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.
Is Grade 8 or 12.9 stronger?
Used in high stress environments, grade 12.9 fasteners are the highest class of metric cap screws. Where Grade 8 fasteners have a 150,000 psi tensile strength, 12.9 fasteners have a 180,000 psi tensile strength, making them more durable than the grade 5.
What does 10.8 mean on a bolt?
This number is 10% of the minimum tensile strength of the bolt (10% of proof strength for nuts). Thus, multiplying this number by 10 will produce the minimum tensile strength of the fastener in MPa.
What grade is an 8.8 bolt?
Grade 8.8 high tensile steel is often referred to as the structural grade for bolts. It is the most common form of high tensile material and is usually stocked in plain finish or zinc. It can be plated in many other coatings.
