Bolts are typically graded on materials, tensile strength, core hardness and thread quality. Bolt grades are determined by measuring body diameter, bolt head size, thread pitch, length and thread length.
In addition, the strength of a bolt is also determined by grade markings found on its head. There are grade markings for both inch and metric bolts.
Grade markings for inch bolts include grade 2, 5, 8 and 9. Grade 2 bolts are made from low-carbon steel and are considered to be the weakest form of bolt. Grade 5 bolts are made from medium-carbon steel and are stronger than Grade 2 bolts, but still relatively low strength.
Grade 8 bolts are made from alloy steel and are much stronger than Grade 2 or Grade 5 bolts. Finally, Grade 9 bolts are made from alloy steel but are even stronger than Grade 8 bolts.
Metric bolts, on the other hand, are typically marked with “Property Classes.” These Property Classes indicate the material and strength of the bolt. The Property Classes range from 4.6 to 10.9, with 6.8 being the most common class found on general-purpose bolts.
10.9 is the strongest class, and is typically used in heavy-duty applications.
Bolts can also be graded based on their core hardness. Core hardness is measured by the Rockwell C hardness scale. Core hardness ranges from very soft (less than 20 HRC) to very hard (greater than 55 HRC).
Soft core bolts are best used in low-tensile applications, while hard core bolts are best used in high-tensile applications.
Finally, thread quality is also taken into consideration when grading bolts. Most bolts use either American National Standards Institute (ANSI) or Unified Thread Standard (UTS) threading. Both ANSI and UTS threading are measured in threads per inch (TPI).
The number of threads per inch can range from very coarse (8 TPI) to very fine (32 TPI). The type of threading used will depend on the application for which the bolt is being used.
How is bolt grade determined?
Bolt grade is determined by the material the bolt is made from, its diameter, and the pitch of the threads. Bolts come in a variety of grades, from low carbon steel (Grade 1, 2, and 3) to high strength or alloy steel (Grades 5 and 8).
Grade 1 bolts are made for general applications where no particular strength is required, and grades 2 and 3 are used for light and medium-duty applications. Grade 5 bolts are made from medium carbon steel and are used for medium-duty applications, while Grade 8 bolts are higher quality and made from alloy steel for heavy-duty applications.
The pitch of the threads is also important in determining bolt grade, as well as whether the bolt is a coarse threaded (more widely spaced threads) or fine threaded (denser thread spacing) type.
What determines the grade of a bolt?
The grade of a bolt refers to its performance metrics and is determined by a number of factors. A bolt’s grade is determined by its material properties, size, strength, threading, and coating. The types of material used for bolts can vary and include steel, aluminum, brass, stainless steel, and titanium.
The strength of the material and its ability to resist corrosion, high temperatures, and wear are important factors in choosing the right grade of bolt. The size of the bolt is also an important factor and related to the intended application and the amount of load or static pressure the bolt will see.
The threading of a bolt affects its ability to form a good connection and the amount of weight it can safely hold. The grade of bolt can also be determined by its coating, which is often determined by its intended application and the environment it will be used in.
In marine environments, for instance, a stainless steel bolt with a galvanized coating may be required for added protection. Ultimately, the right grade of bolt depends on the application and the conditions it will be subjected to.
Is Grade 8 or 12.9 stronger?
Grade 8 and 12.9 are two different grades of steel, each with its own set of strengths and weaknesses. Grade 8 is generally the stronger of the two, as it contains more alloying elements and therefore has higher tensile strengths.
Grade 8 is known for its strong resistance to corrosion, high tensile strength, and high wear resistance. On the other hand, Grade 12.9, though it has a higher hardness, is a relatively low-alloy steel.
It has a good combination of strength and ductility, but is not as strong as Grade 8 and is not as resistant to corrosion. In general, Grade 8 is the stronger of the two grade steels and is the better choice for applications that require extreme strength, corrosion resistance, and durability.
How is a Grade 5 bolt identified?
A Grade 5 bolt is identified by the presence of three radial lines on the head of the bolt. These radial lines indicate that the bolt is made of high-strength steel and is Grade 5. Grade 5 bolts are usually used to join heavy parts together, such as transmission housings, exhaust flanges and wheels.
They can also be used for projects that require a higher strength bolt, such as suspension components and aircraft struts. Grade 5 bolts are easily identified by their markings, which are located near the head of the bolt.
There should be a ‘5′ followed by the letter ‘F’ along with the three radial lines. Grade 5 bolts are significantly stronger than standard bolts, so they should never be used in any application that doesn’t require their high strength.
Are Grade 8 bolts stronger than 5?
Yes, Grade 8 bolts are stronger than Grade 5 bolts because they are made from a stronger alloy. Grade 8 bolts are composed of an alloy that contains a minimum of 0.28% carbon, and a tensile strength of at least 120,000 PSI.
In comparison, Grade 5 bolts are composed of an alloy that contains 0.20% – 0.25% carbon, and a tensile strength between 81,000 and 120,000PSI. Grade 8 bolts also have a higher yield strength, meaning they have a better ability to maintain their integrity under pressure.
In contrast, Grade 5 bolts have a slightly lower yield strength, meaning they may experience slight stretching or eating before they become completely compromised.
What identification markings does a SAE Grade 5 bolt have?
The identification markings for a SAE Grade 5 bolt are typically a number denoting the diameter of the bolts shank in inches, either the letter “U” or the word “grade” followed by the grade number “5” and the letters “SAE”.
For example, a 1⁄4 inch SAE Grade 5 bolt would be marked “1/4 U 5 SAE”, and a 1⁄4 inch Grade 5 bolt would be marked “1/4 grade 5 SAE”. While the grade 5 is the most common grade of SAE bolt, it is sometimes preceded by other grade numbers (from lower to higher strength) such as Grade 2, Grade 5, Grade 8, and Grade 9.
Is A307 a Grade 5?
No, A307 is not a Grade 5. Grade 5 is generally used to refer to a student’s academic performance in a school or college setting, and is typically given on a scale of 1-10 or A-F. A307 is a steel alloy, and is typically given a strength rating such as A307A or A307B.
How are high strength bolts identified?
High strength bolts are identified by Grade markings that designate the strength of the bolt. Grade markings are typically stamped onto a bolt head, and indicate the type of steel used to manufacture the fastener, its strength rating, the standards the bolt was manufactured to and the property class (temperature resistance, chemical resistance, higher strength, hardness, and fatigue strength).
Common grades of high strength bolts are Grade 5, Grade 8 and ASTM A325 and A490. Grade 5 bolts can withstand tensile forces of 120,000 psi, Grade 8 bolts can handle 150,000 psi and ASTM A325 and A490 bolts can handle up to 120,000 psi and 170,000 psi respectively.
The standards the bolt was manufactured to can be identified by either a three-digit code or certain numbers and letters. For example, Grade 5 bolts use the number “5,” Grade 8 bolts use the code “8” and ASTM A325 and A490 bolts use the letters “A” and “X”.
Property classes assigned to grade 5 and grade 8 bolts are numerals ranging from 1 to 8, while ASTM A325 and A490 bolts are marked with the digits “5” and “6”, respectively.
How are bolts specified and identified?
Bolts are typically specified and identified by taking measurements of their length, thread count and thread size. The length is typically calculated from the unthreaded part to the beginning of the threading.
Thread count is the number of threads per inch or centimeter and thread size is the diameter of the threads on the bolt. Different measurements are necessary for different applications. Additionally, bolts are categorized based on their head shape, which indicates its drive type, as well as its grade, which indicates its strength and hardness.
Furthermore, coatings, surface treatments and finishes can also be applied to the bolt to provide extra protection and durability. For example, galvanization dose zinc to the bolt to protect it from corrosive elements.
Is a 10.9 bolt stronger than Grade 8?
It depends on the application and the context of the bolt in question. A Grade 10.9 bolt is considered to be stronger than Grade 8, as it is made from a higher quality and stronger steel alloy, and is heat treated with lower-temperature techniques which result in a more fatigue resistant bolt.
The higher alloy content also increases the strength of the bolt, but it also makes it more brittle overall. The higher grade also comes with an increase in cost and a decrease in corrosion resistance.
The conditions of the application need to be taken into consideration to decide if a Grade 10.9 bolt is a better choice than Grade 8. If the application involves vibration, such as a motor mount, or motion, or if it is in an application that is near saltwater or chemicals, then Grade 10.9 may be a better choice.
However, if the application is not subjected to those conditions, Grade 8 may be a more economical and robust choice.
What is stronger Grade 5 or Grade 8 bolts?
Grade 8 bolts are stronger than Grade 5 bolts. This is because Grade 8 bolts have a higher tensile strength than Grade 5 bolts. The tensile strength of a Grade 8 bolt is greater than 150,000 psi, while the tensile strength of a Grade 5 bolt is less than 120,000 psi.
Grade 8 bolts also have six uniform lengths that make them more suitable for use in various applications, while Grade 5 bolts are designed to be used mainly in non-critical applications. Grade 8 bolts also feature much tighter tolerances than Grade 5 bolts, meaning they are less prone to loosening over time.
In summary, Grade 8 bolts are much stronger and more secure than Grade 5 bolts and are therefore the better choice for critical applications.
What are Grade 9 bolts used for?
Grade 9 bolts are a high-strength steel alloy with a minimum tensile strength of 150,000 PSI. They are typically used in highly stressed applications such as engine and transmission mounts, cylinder head bolt joints, drive shafts, and shock absorbers.
Grade 9 bolts feature a greater resistance to vibrational loosening than regular bolts, meaning they will not loosen as easily from excessive shaking or vibration. They are also resistant to extreme temperature variations, making them ideal for use in both hot and cold weather conditions.
As with other bolts, Grade 9 bolts range in size from a small ¼” diameter to a large 2 ½” diameter, so they can be used in a wide array of applications. Grade 9 bolts are also commonly used in high-heat applications such as exhaust manifolds, turbine housings, and turbochargers.
What grade bolt is a shear pin?
The grade of bolt used for shear pins depends on the specific application. In general, however, A2 stainless steel is the standard material used as shear pins. Grade A2 stainless steel is an austenitic stainless steel which contains 18-20% chromium and 8-10% nickel.
It is non-magnetic and heat treatable. Additionally, it’s resistant to nitric acid, strong in oxidation and corrosion resistance, and has good formability, weldability, and excellent workability features.
It is important to consider the strength of the shear pin and the application at hand when choosing the grade of bolt for a shear pin. Grade A2 bolts have the appropriate strength and grade for most shear pin applications.
How strong is a Grade 12.9 bolt?
Grade 12.9 bolts have a tensile strength a minimum of 1290 MPa meaning it can resist forces up to 1290 MegaPascals. The minimum ultimate tensile strength for these bolts is typically around 1553 MPa and can range up to 1855 MPa depending on the manufacturer and type of bolt used.
Grade 12.9 bolts also feature a hardness range from 38 to 44 HRC, meaning they are well-suited to applications that require a lot of wear resistance and strength. As compared to the lower grade bolts, Grade 12.9 bolts are much stronger and can be used in constructions that require lighter weight, superior strength, and better chemical resistance.
They are typically used for heavy load application, such as for heavy haul trailers joints, for mining operations, and in automotive engineering. All in all, Grade 12.9 bolts are incredibly strong and dependable and will provide reliable performance in a wide range of applications.
