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 |

105,000 | ||

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 |

1

## What is a grade 8.8 bolt?

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.2

## What is the strength of a grade 5 bolt?

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.3

## What is a Grade 8 bolt?

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.4

## What is stronger grade 5 or 8 bolt?

**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**.

5

## What is a Grade 9 bolt?

**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.

6

## Which is stronger grade 8 or stainless steel?

**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**.

7

## What does 12.9 mean on a bolt?

**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.

8

## What is the difference between metric and standard bolts?

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.9

## Are Grade 8 bolts through hardened?

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.10

## Are Grade 8 bolts rust proof?

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**.11

## What is a b7 bolt?

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.12

## What do the marks on the head of a bolt mean?

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.13

## What is yield strength of bolt?

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.14

## What is proof strength of bolts?

**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**.

15

## What is the tensile strength of a 10.9 bolt?

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.16

## What is a high tensile 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.17

## What does class 10.9 bolt mean?

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**.18

## What is the SAE grade?

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**30.19

## What is ASTM a325?

**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.