How do you tell what grade a metric bolt is?

How do you tell what grade a metric bolt is?

Strength Grades for metric fasteners are designated by a symbol comprised of 2 numbers, separated by a decimal. For example, 4.6 and 8.8. The first number represents 1/100 of the nominal tensile strength in N/mm^2.

What do numbers on bolts mean?

In addition, most metric bolts are identified by a number stamped on the bolt head, such as 4.6, 5.8 or 10.9. The number has nothing to do with the size, but does indicate the relative strength of the bolt. The higher the number, the stronger the bolt. A metric fastener could be designated M12 x 2, for example.

How do you know if a bolt is Grade 5?

Grade 5 bolts are case hardened, meaning the bolt has been heated enough to hardened the outside of the bolt but not enough to harden the inside portion. Grade 5 bolts are identified by 3 evenly spaced radial lines on the head.

Is Grade 8 or 10.9 stronger?

Class 10.9 is stronger than class 8.8. It is commonly found in high strength automotive applications. Class 10.9 is similar to grade 8. A low carbon steel for general use.

What is a grade 4.6 bolt?

The specification Class 4.6 Threaded Rod is a standard that covers fasteners manufactured from either Low carbon steel or medium carbon steel. The ultimate material strength of Grade 4.6 Threaded Rod is 40 Mpa while its yield strength or the proof stress is 60% that of the ultimate strength.

How do you identify metric threads?

Metric threads are measured by their pitch. That is the distance from the crest of one thread to the crest of the next measured in millimetres. The pitch of a metric thread can be checked by direct measurement with a metric rule. Imperial threads have their pitch measured indirectly as a given number of teeth per inch.

What is the marks on a Grade 5 metric bolt?

The markings can identify the standard to which the bolt was made. For instance, if a bolt head contains three radial lines, then it’s a Grade 5 bolt. If it contains five radial lines, then the bolt is Grade 8.

What does 9.8 on a bolt mean?

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 grade is a 8.8 bolt?

Grade 8.8 Bolts belong to the DIN 933 grade 8.8 standard. This is a structural grade for bolts. This is a medium carbon steel bolt specification. These bolts are heat treated by quenched and tempered methods.

What are bolt grades?

The grade of a bolt determines the maximum amount of stress (tensile strength) that the bolt can handle. The SAE marking system uses raised dashes on the bolt head to indicate strength. Metric Bolt Grades—Metric grades are set according to rules set by the ISO (International Standards Organization).

How do I identify the grades of bolts?

This chart helps to identify the grades of bolts using the identification marks on the bolt’s head along with the strength and hardness of common grade bolts. Please note the bolt heads may also include the manufacturer’s identification stamp, especially with high strength bolts.

What is the Qu ality ISO grade marking for bolts?

Q U ALITY ISO GRADE IDENTIFICATION MARKINGS – INCH STEEL BOLTS Grade Marking Specification / Description Material Nominal Size inches Proof Load psi Tensile Strength min psi Yield Strength min psi Rockwell Hardness min max SAE J429 – Grade 1Bolts, screws, studs Low or medium carbon steel 1/4 – 1 1/2 33000 60000 36000 B70 B100

What are the different grades of ASTM bolts?

ASTM A325 Type 3High strength structural bolts Atmospheric corrosion resistant steel, quenched & tempered 1/2 – 1 1 1/8 – 1 1/2 85000 74000 120000 105000 92000 81000 C24 C19 C35 C31 B B ASTM A354 Grade BBBolts, studs Alloy steel, quenched & tempered 1/4 – 2 1/2 >2 1/2 – 4 80000 75000 105000 100000 83000 78000 C26 C22 C36 C33

What does the X mean on bolts and screws?

Manufacturer’s identification mark, e.g., “X” ( on head of bolts and screws and on one end of studs and stud bolts). ASTM A 193 Grade B8M Class 2 (Strain Hardened Material) Regular Series and Heavy Series 67611. B 8 M X. Symbol for identification of grade, i.e., “B8M”, applied to head.