Bolt Grade Markings & Strength Chart - Inch Steel Bolts
| Head Marking | Bolt Grade / Specification | Material | Nominal Size (Inch) | Rockwell Hardness Min/Max |
| Grade 1 - SAE J429 Bolts, Screws and Stu ... | Low or medium carbon steel | 1/4" - 1-1/2" | B70 / B100 | |
| Grade 2 - SAE J429 Bolts, Screws and Stu ... | Low or medium carbon steel | 1/4" - 3/4" >3/4" - 1-1/2" | B80 / B100 B70 / B100 | |
| Grade 5 - SAE J429 Bolts, Screws and Stu ... | Medium carbon steel or carbon steel with ... | 1/4" - 1" >1" - 1-1/2" | C25 / C34 C19 / C30 |
Which is stronger grade 8 or grade 5 bolts?
There exists an often quoted myth, that Grade 5 bolts are better in shear than Grade 8 since they will bend before breaking. Not true. Shear strength of alloy steel is approximately 60% of its ultimate tensile strength. Reference to Table 1 shows that the yield strength of a Grade 8 bolt is higher than the ultimate strength of a Grade 5 bolt.
What is the shear strength of a Grade 5 bolt?
Grade 5 carriage bolts are made from carbon steel and have a tensile strength of 120,000psi, and have a proof load strength of 85,000psi. They have a tensile strength of 150,000 psi and a shear strength of 90,000 psi.
What material is a Grade 5 Bolt made of?
Grade 5. Grade 5 alloy steel is a medium carbon zinc plated alloy steel that is heat treated to increase hardness. Grade 5 bolts have three (3) evenly spaced hash marks on the head markings (manufacturers mark may also be included). Grade 8 / Grade G. Grade 8 zinc plated alloy steel bolts are thru-heated and thru-hardened with a CR+5 zinc plating.
What are the different grades of bolts?
- SAE Bolt Grades—The standards for bolt strength grades in the U.S. ...
- Metric Bolt Grades—Metric grades are set according to rules set by the ISO (International Standards Organization). ...
- ASTM Bolt Grades—The ASTM grade standard is set by the American Society for Testing and Materials. ...
How much can a Grade 5 bolt hold?
A Grade 5 bolt tensile strength is 120,000 psi for bolts 1/4- to 1-inch long. Bolts over 1 to 1.5 inches long must provide a tensile strength of 105,000 psi. The ASTM tensile strength specification for a Grade 5 bolt is 90,000 psi for bolts from over 1.5 to 3 inches.
What grade bolt is the strongest?
grade 8Grade 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.
What is a stronger bolt Grade 5 or Grade 8?
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 a Grade 5 bolt used for?
Grade 5 is specified under the Society of Automotive Engineers and is meant to be used for those applications requiring medium strength. Equivalent to the metric class 8.8 bolts, it is important to line up the right hardware if required to move from U.S. customary units (USC) to the metric system.
Are stainless steel bolts stronger than Grade 5?
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 there a Grade 7 bolt?
Available grades run from 2 to 8, with 8 the strongest. Higher grade numbers almost always mean increased strength (an exception is that some grade 6 bolts were stronger than grade 7). Low- or medium-carbon steel.
What is the strongest metal bolt?
BUMAX® Ultra has proven itself as the world's strongest bolt – in various highly-demanding critical fastener applications around the world where standard fasteners are simply inadequate.
What is the best bolt for shear strength?
Grade 8 bolts exhibit greater tensile, yield, and shear strength as well as greater fatigue resistance and, just as important, are capable of greater torque specs and therefore much greater pre-load and clamping strength.
Will a Grade 5 bolt 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. Bolts are typically marked on the head to show what grade bolt they are.
Are all grade 5 bolts the same?
The standard thread length which both grades come with also differ. Grade 5 bolts, similar to most grades, follow the standard thread length formula of two times diameter plus 1/4″ or 1/2″, depending on if the bolt is up to or over 6″ in length.
Is there a bolt stronger than Grade 8?
There are several grades of bolts but the three common grades for SAE are 2, 5 and 8. The common class (grades) for metric are 5.8, 8.8, 10.9 and 12.9. Each grade has a specific bolt strength. No matter the system used to grade the bolts, the higher number means the stronger the bolt.
What are high strength bolts?
High Strength Bolts For Structural Bolting Bolts are fasteners with external threads designed for driving through holes in assembled parts. These fasteners are tightened or released through torqueing a nut. High strength bolts are made from high-strength carbon steel or from tempered alloy steel.
Comparing Shearing Strength Of Grade 8 Vs Grade 5 Bolts
The shear strength is the breaking tension, representing the maximum force required to break a bolt.
Usage Of Grade 8 And 5 Bolts
The higher-grade number indicates a higher strength and flow stress for the bolt material. Grade 8 bolts are suitable for use where very high strength is required, such as suspension bridges, wind turbines, and other heavy-duty applications in both light steel and concrete structures.
In Brief: SAE Bolt Torque Chart – Grade 2, Grade 5, Grade 8
SAE bolt grades indicate the strength of the bolt. Each bolt grade has an ideal tightening torque for maximum clamping force without breaking. Grade 2 bolts are cheap but not very strong, grade 8 bolts are the strongest and most expensive, and grade 5 bolts are the most common. Refer to the charts to find the ideal tightening torque.
Bolt Torque Charts for Grades 2, 5, and 8
Bolts must be tightened using the correct torque. Properly torqued bolts will provide the maximum amount of clamping force under load.
SAE Grade 2 Bolt Torque Chart
Grade 2 bolts are used for applications that require fastening but do not require the bolt to undergo heavy load.
SAE Grade 5 Bolt Torque Chart
Grade 5 bolts offer more strength and corrosion resistance than the grade 2 bolts and tend to see more use even though they cost a bit more. Most of the time, you will want to use grade 5 bolts.
SAE Grade 8 Bolt Torque Chart
Grade 8 bolts are the strongest commonly used bolts outside of industrial applications.
Summary
We hope this guide on SAE bolt tightening torques has helped you with your project.
What is the size of a bolt?
Bolts. The basic parts of a bolt are: Head – commonly sized 4/16ths larger than the nominal size of the bolt (diameter of the shank). For example, a 1/2 inch bolt has a head that takes a 3/4 inch socket.
How many threads should a bolt have?
As a rule of thumb a bolt should protrude through a nut by at least 3 full threads. The reason for this is because often the first 2 or 3 threads of a bolt are poorly formed, usually due to a chamfer on the end of the bolt for easier starting. Thus they will not produce the full strength of the fastener.
How to tighten a fastener to spec?
The proper technique for tightening a fastener to spec is as follows: Tighten the fastener a little at a time (3 or more steps), pausing to allow the stress in the threads to relax. Finish with an even pull until the torque wrench clicks or indicates final torque, pause, and then pull again to check.
How do nuts and bolts work?
Nuts and bolts are clamps. They work by tightly clamping the parts of a bolted joint together. They are able to do this because of stress and strain. When a nut and bolt is tightened in a joint, the bearing surface of the bolt and the nut face come up against the halves of the joint.
Why are internal threads weaker than rolled threads?
Because the only practical way to form the internal threads is to cut them into the nut, these threads are always weaker than the rolled threads of a quality bolt or stud. Selection of an appropriate nut consists of choosing the correct grade and thread to match the bolt used.
What are the parts of a bolt?
The basic parts of a bolt are: 1 Head – commonly sized 4/16ths larger than the nominal size of the bolt (diameter of the shank). For example, a 1/2 inch bolt has a head that takes a 3/4 inch socket. 2 Bearing Surface – machined true and perpendicular to the shank, the bearing surface is the area through which the bolt is loaded in tension. 3 Shank – unthreaded portion of the bolt. Its diameter is the nominal size of the bolt (equal to major diameter of thread). 4 Male Threads – the threads on a bolt, screw, or stud are known as "male," those on a nut or tapped hole are "female." 5 Point – the extreme end of the threads, often chamfered for easier thread starting. 6 Grip Length – the length from the bearing surface to first complete thread. 7 Thread length – how much of the shank is threaded from point to last complete thread. 8 Length – the total length of the bolt (the dimension you specify when purchasing) is the total of the grip length and the thread length.
What is a male thread?
Male Threads – the threads on a bolt, screw, or stud are known as "male," those on a nut or tapped hole are "female.". Point – the extreme end of the threads, often chamfered for easier thread starting. Grip Length – the length from the bearing surface to first complete thread.
What are the forces of a bolt?
There are two types of forces a bolt experiences, tension and shear. One goes up and down while the other goes side to side. Its often in the shear aspect that people assume lower grade bolts are better in places like suspension systems. However, as you can see in the following table, both tension and shear are higher in Grade 8 bolts ...
Is a higher rated bolt stronger?
One common misconception about bolts is that a higher rated bolt is stronger, yet more brittle, and therefore lower grades should be used in places like in suspension systems so they can deform rather then break. This is wrong! There are two types of forces a bolt experiences, tension and shear.
Can you use a lower grade bolt for bending?
So to use a lower grade bolt for the the purposes of it bending versus breaking, unfortunately that is incorrect. The lower grade bolt will reach its maximum elongation and reach its fracture point well before the higher grade even begins deforming.
