Ferrous : Non-Ferrous : Polymers : Ceramics : Bolts : Springs : Thermodynamics : Bending : Stress

 

Bolt Grades 

Table 1: NOMINAL BOLT PROPERTIES
(Use these for calculations)

Bolt 

Grade

Sizes

UTS 

100 x #1

Yield Stress 

UTS x #2 / 10

Proof Load

90% x Yield  

Preload

80% x Proof 

Hardness 

Rockwell  

 

mm diam

MPa

MPa

MPa

MPa

Min

4.6

M5-M100

400

240

216

172

B67-95

4.8

M1.6-M16

400

320

288

230

B71-95

5.8

M5-M24

500

400

360

288

B82-95

8.8

M16-M72

800

640

576

460

C23-34

9.8

M1.6-M16

900

720

648

518

C27-46

10.9

M5-M100

1000

900

810

648

C33-49

12.9

M1.6-M100

1200

1080

972

777

C38-44


Proof Load:(MPa) Stress that the bolt must withstand without evidence of any permanent set, usually about 90% or Yield Strength.. 
Proof Stress:(MPa) The stress that produces a certain strain, typically 0.2%. Used for materials that do not have a definite yield point. 
PreLoad Stress:(MPa) The stress that a bolt is normally tensioned up to. Typically 80% of the stress Proof Load, which is 72% of Yield. 

Note: These are NOT THE SAME! Proof Stress is above the Yield Stress, but Proof Load is below it.



Table 2: MEASURED TYPICAL BOLT PROPERTIES:
Source: ISO 898-1, 1999, Sections 3 through 7, and App. A.
(Do NOT use these for calculations)

Bolt 

Grade

Sizes

UTS

Yield Stress

Proof Load

Hardness 

Rockwell  

 

mm diam

MPa

MPa

MPa

Min

4.6

M5-M100

400

240

225

B67-95

4.8

M1.6-M16

420

340

310

B71-95

5.8

M5-M24

520

420

380

B82-95

8.8

M16-M72

830

660

600

C23-34

9.8

M1.6-M16

900

720

650

C27-46

10.9

M5-M100

1040

940

830

C33-49

12.9

M1.6-M100

1220

1100

970

C38-44

 

Links
Bolted Joints:  http://www.roymech.co.uk/Useful_Tables/Screws/Preloading.html

Material Properties: