What is the Rockwell hardness of a Grade 5 bolt?
There is also difference in the core Rockwell hardness between Grade 8 and Grade 5 bolts. Grade 8 typically has a core Rockwell hardness of C33-C39, while Grade 5 have a core Rockwell hardness of C25-C34.
What is the shear strength of a Grade 5 bolt?
The shear strength is the breaking tension, representing the maximum force required to break a bolt. The grade 8 bolts have a breaking point of 2,500 pounds per square inch (psi), while grade 5 bolts have 1,200 psi. As you can see, grade 8 bolts are stronger than their counterparts in every way.
How strong is a Grade 5 bolt?
Most of the time, you will want to use grade 5 bolts. They are made from quenched and tempered medium carbon steel and bear a 3-line mark on the head. They have a proof load of 85000 psi, minimum yield strength of 92000 psi, and a minimum tensile strength of 120000 psi. Table 1 – SAE Grade 5 Bolt Torque Chart SAE Grade 8 Bolt Torque Chart
What material is a Grade 5 Bolt made of?
Grade 5 Bolts and fasteners are made of medium strength carbon steel and are specified under the Society of Automotive Engineers (SAE). If your application calls for heavier materials, you may need Grade 8 Bolts because they are the hardest and are often used in heavy manufacturing applications.
What is a grade 5 bolt?
A Grade 5 bolt typically connects metal to metal.
What is the yield strength of a bolt?
This measurement is also given in pounds per square inch. The yield strength specification for a Grade 5 bolt is 92,000 psi for bolts 1/4- to 1-inch long. Bolts over 1 to 1.5 inches long must endure a yield strength of 81,000 psi. The ASTM requires the yield strength specification for a Grade 5 bolt to be 58,000 psi for bolts from over 1.5 to 3 inches. The equivalent ISO bolt must have yield strength of 92,000 psi for all bolt sizes.
What is the proof load of a bolt?
Proof load measures the direct load (tension applied) that a fastener must support without visible distortion. This measurement is given in pounds per square inch (psi). The proof load specification for a Grade 5 bolt is 85,000 psi for bolts 1/4- to 1-inch long. Bolts over 1 to 1.5 inches long must endure a proof load of 74,000 psi. The ASTM requires the proof load specification for a Grade 5 bolt to be 55,000 psi for bolts from over 1.5 to 3 inches. The equivalent ISO bolt is an 8.8 and must proof load 85,000 psi for all bolt sizes.
Which bolt is better grade 5 or grade 2?
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.
What is the grade of SAE bolt?
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.
How to tell which bolt you are working with?
You can tell which bolt you are working with by the markings on the head. Compare the bolts you have with the diagrams below, then refer to the appropriate chart to see the ideal tightening torque.
What is the minimum tensile strength of a sandpaper?
They have a proof load of 120000 psi, minimum yield strength of 130000 psi, and a minimum tensile strength of 150000 psi.
Who designed the bolt grading system?
Bolts are graded using various systems, but in the United States, the main bolt grading system was designed by SAE , the Society of Automotive Engineers.
Do bolts need to be tightened?
Bolts must be tightened using the correct torque. Properly torqued bolts will provide the maximum amount of clamping force under load.
How much weight can a grade 2 bolt hold?
When considering the Proof Load, this is the amount of weight the bolt itself can support. Grade 2 bolts can support between 33,000 and 55,000, and so on. So if the join you are considering will be below the minimum yield strength, you should be good to go.
What is a grade 2 bolt?
Grade 2 bolts are the most common grade of bolts and are also the least expensive. Grade 2 bolts are found mostly in household fasteners like carriage bolts, and machine screws. The usually have no head marking, but may sometimes contain manufacturer markings.
Why are grade 8 bolts more likely to snap off than bend?
They are fully heat treated all the way through which create a bolt that is very hard but somewhat brittle. Because of their hardness, grade 8 bolts are more likely to snap off than bend under extreme loads. Grade 8 bolts are identifiable by 6 evenly spaced radial lines on the head.
What is the yield strength of a bolt?
Well, where "yield strength" is where the bolt starts to "give," or deform plastically, the "tensile strength" of a bolt, or bolt grade, is when that bolt will actually break.
What is the minimum yield strength?
With the minimum yield strength--this is the amount of weight it will take for the bolt itself to show signs of physical deformity, bending, stretching or cracking.
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.
The Nut and Bolt Solution Series
A common question is whether stainless steel is stronger that a grade 5 or grade 8 bolt. Stainless commonly comes in grades 18.8 (304) or T316. 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).
Video 10: Stainless Steel Bolt Grades & Strength
The Nut and Bolt Solution Series Index - View the entire fastener video "how to" series
What is the tensile strength of a bolt?
Tensile strength is the amount of pull the bolt can withstand before breaking. A bolt head with three raised dashes in a radial pattern marks an SAE grade 5 bolt of tempered medium carbon steel with a tensile strength of at least 105,000 pounds per square inch.
What is the strength of a metric bolt?
The higher the ISO numbers are, the stronger the 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.
What is the ASTM A325 bolt?
Common ASTM grades include A307, which roughly corresponds to SAE Grade 2. An ASTM A325 bolt is roughly equivalent in strength to SAE Grade 5 and an A490 bolt is about equivalent in strength to SAE Grade 8. Herb Kirchhoff has more than three decades of hands-on experience as an avid garden hobbyist and home handyman.
What does the head marking on a bolt tell you?
Hunker may earn compensation through affiliate links in this story. Bolt head markings tell you if it's strong enough for the job. Bolts are made of different grades of steel. The greater the steel's tensile strength, the more torque the bolt can take and the tighter the bolted joint will be.
What is metric grade?
Metric Grades. The strength grade of a metric bolt, known as its property class, consists of two numbers separated by a dot. The property class is expressed in raised or depressed numerals on top or on the side of the bolt head, according to rules set by the International Standards Organization. The first number represents ...
