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|
Is a 10.9 Bolt stronger than Grade 8?
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.
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|
The first digit relates to the ultimate strength of the material, whilst the second is the ratio of yield stress to ultimate strength. Thus grade 4.6 bolts have an ultimate material strength of 400N/mm2 and the uield (or proof) stress is 60% of the ultimate strength.
In that case, shear strength is important to you. Mark's Standard Handbook for Mechanical Engineers lists Grade 5 fasteners as 120 ksi fasteners. This means the tensile strength is 120,000 lbs per square inch. It also lists Grade 8's as 150 ksi fasteners meaning the tensile strength is 150,000 lbs per square inch.
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.
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. Grade 8 bolts have 6 evenly spaced radial lines on the head. Grade G is roughly equivalent to Grade 8.
Grade 9 Hex Head. The Grade 9 Bolting system develops the highest clamp force available in a standard bolt/nut assembly and it is frequently referred to by one of the folowing trade names: L9, PFC9, or F911. Special Alloy steels and heat treatments are used to achieve 180,000 psi tensile strength.
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.
12.9 grade steel means that a component manufactured form this grade of steel has 12X100 N/mm^2 tensile strength and 9 is a multiplier means 90% of 1200 = 1080 N/mm^2 is the yield strength of the grade. Similarly we also have grade 8.8 , 10.9 , 6.8 also.
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.
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.
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.
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.
Sometimes there are lines on the bolt head. The lines on the head of a bolt indicate its grade. SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade.
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.
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.
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.
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.
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.
The Society of Automotive Engineers (SAE) has established a numerical code system for grading motor oils according to their viscosity characteristics. The original viscosity grades were all mono-grades, e.g. a typical engine oil was a SAE 30.
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.