Also known as A-2 stainless, 18-8 is the most common grade of stainless steel for general use. A tempered medium carbon steel. Class 10.9 is stronger than class 8.8, and is commonly found in high strength automotive applications. Class 10.9 is similar to grade 8.
Keeping this in consideration, how many marks are on a Grade 8 bolt?
Bolt Grade Markings and Strength Chart
|Head Marking||Grade and Material||Mechanical Properties|
|Min. Tensile Strength (psi)|
|3 Radial Lines||Grade 5 Medium carbon steel, quenched and tempered||120,000|
|6 Radial Lines||Grade 8 Medium carbon alloy steel, quenched and tempered||150,000|
What is the hardness of a Grade 8 bolt?
Materials - Medium Carbon Steel Bolts in SAE J429 (Grades 2, 5 and 8)
|Grade||Nominal size, inches||Core hardness, Rockwell|
|2||¾ - 11/2 inch||B70 to B100|
|5||¼ - 1 inch||C25 to C34|
|1 - 1-1/2 inches||C19 to C30|
|8||¼ - 1-1/2 inches||C33 to C39|
Grade 8 bolts have a proof load of 120,000 pounds per square inch. The minimum strength of stainless steel bolts is 40,000 to 90,000 psi. The minimum strength of grade 8 bolts is 130,000 psi. Grade 8 bolts are much stronger than stainless steel.
According to K-T Bolt Manufacturing Inc., Grade 8 bolts "are used in demanding applications such as automotive suspensions. 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.
M 10 x 1.5 is a metric bolt with a 10 mm nominal diameter and 1.5 mm pitch. The standard American bolt is defined by the inch system designation. For both metric and standard bolts, the head size is the distance across the flats. For standard bolts, the head size is measured in inches or fractions of an inch.
ASTM A193 Grade B7 bolts and threaded studs are manufactured from a chromium-molybdenum steel and are quenched and tempered (heat treated) to develop the desired mechanical properties (strength). Grade B7 is the most common grade of A193 bolts used in construction.
Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 840 °F (449 °C).
The proof load represents the usable strength range for certain standard fasteners. By definition, the proof load is an applied tensile load that the fastener must support without permanent deformation. Figure 1 illustrates a typical stress-strain relationship of a bolt as a tension load is applied.
For the 10.9 bolt, the 9 tells the user that the yield strength of the bolt is approximately 90% of the first number: 1,000 MPa. Thus, the 10.9 bolt has an approximate yield strength of 900 MPa (940 MPa by specification). Two other common symbols that are included on metric parts are the "S" and the 3 designations.
Our metric grade 10.9 bolts meet ASTM A324 grade BD and SAE J429, grade 8 standards. The yield strength of the bolts is 940 and the tensile strength is 1040 MPa. U-Bolt-It is a leading distributor and manufacturer of high quality metric grade 10.9 bolts.
Most often, customers looking for a high tensile bolt may just be looking for the 8.8 grade. · S- An S grade refers to the tensile strength of industrial fasteners, or the maximum amount of stress these fasteners and fixing can withstand before they begin to break or fail.
Proof load is defined as the maximum tensile force that can be applied to a bolt that will not result in plastic deformation. In other words, the material must remain in its elastic region when loaded up to its proof load. Proof load is typically between 85-95% of the yield strength.
ASTM A325 is an ASTM International standard for heavy hex structural bolts, titled Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength. It defines mechanical properties for bolts that range from 1⁄2 to 1 1⁄2 inches (13 to 38 mm) in diameter.
Offset yield point (proof stress) When a yield point is not easily defined based on the shape of the stress–strain curve an offset yield point is arbitrarily defined. The value for this is commonly set at 0.1 or 0.2% plastic strain.
A locknut, also known as a lock nut, locking nut, prevailing torque nut, stiff nut or elastic stop nut, is a nut that resists loosening under vibrations and torque. Elastic stop nuts and prevailing torque nuts are of the particular type where some portion of the nut deforms elastically to provide a locking action.
For example, Carroll Smith (Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook) notes that the nylon insert is not damaged by installation and therefore they can be reused many times, and a Federal Aviation Administration Advisory Circular allows nuts to be reused if the prevailing torque is within
PREVAILING TORQUE. The torque required to run a nut down a thread on certain types of nuts designed to resist vibration loosening. The resistance can be provided by a plastic insert or a noncircular head. PREVAILING TORQUE NUT. A type of lock nut which has a prevailing torque to assist in preventing self loosening.
Breakaway torque is the rotating force required to "break" the head loose, going in the same direction as applied - tightening. This will usually give a value HIGHER than the original tightening torque because dynamic (when the bolt was tightened) is lower than static (when you try to break loose the bolt head).
Pre-Load — A measure of the axial load imparted on a fastener. A result of the amount of the applied seating torque, typically measured in pounds per square inch (psi) to create tension in the fastener. Commonly accepted to be 80-85% yield strength. Prevailing Torque: Also known as “Running Torque”.
The raw dough is your low carbon or grade 2 bolt. The case hardened or through hardened grade 8 bolt has been really cooked. Not only is the outside crispy, but you would be hard pressed to put a fork in it as it has been hardened by heat treatment all the way through. It is made with medium alloy steel.
In engineering, shear strength is the strength of a material or component against the type of yield or structural failure where the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force.
If you have ever looked a metric hex bolt you might notice the markings 8.8, 10.9 or 12.9 this does not mean grade 8,10 or 12. The grade 8.8 refers to the tensile strength which is generally 116,000 psi, grade 10.9 is generally 150,000 and grade 12.9 is generally 175,000 psi.