Raw Material

 
   Raw Material in M S  
 
Technical Details :
   
Scope and Field of Application
 

The Property Classes and thier mechanical properties apply to bolts, screws, and studs, with metric(ISO) thread, with nominal thread diameter d<= 39 m, made of carbon steel or alloy steel and when tested at room temperature.
They do not apply to set screws and similar or to specific requirments such as weldability, corrosion resistance, ability to withstand temperatures above +300 0 C or below -50 0 C . The designation system may be used for sizes (e.g. d>39 mm), provided that all mechanical requirements of the property classes are met.

   
Designation system of property clases
 

The property class symbols, indicating the most important mechanical properties, consist of two figures, one on either side of a dot. for example 10.9. The first figure indicates 1/100 of the nominal tensile strength in N/mm2  (see R   in the table)
So property class 10.9 has a tensile strength of 10 x 100 = 1000 N/mm 2
The second figure indicates 10 times the ratio between lower yield stress R (or proof stress R) and nominal tensile strength R (yield stress ratio). so at property class 10.9 the second figure 9 = 1/10 X 900 N/ mm2  .  

   
Mechanical properties of bolts, screws and studs
 
      Property Class
 

Mechanical property

  3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9
d<16mm d>16mm
1

tensile strength

nom. 300 400 500 600 800 800 900 1000 1200
2 R N/mm2 min. 330 400 420 500 520 600 800 830 900 1040 1220
3 Vickers
hardness

HB
F>98n

min. 95 120 130 155 160 190 250 255 290 320 385
max. 250 320 335 360 380 435
4 Birnell
hardness

HB
f= 30D2

min. 90 114 124 147 152 181 238 242 276 304 366
max. 238 304 318 342 361 414
5 Rockwell
hardness

HR

min. HRB 52 67 71 79 82 89 - - - - -
HRC - - - - - - 22 23 28 32 39
max. HRB 99.5 - - - - -
HRC - 32 34 37 39 44
6 Surface hardness
   HV      0.3max.
- 51
7 Lower yield stress
R 6)
N/mm2
nom. 180 240 320 300 400 480 - - - - -
max. 190 240 340 300 420 480 - - - - -
8 Proof stress

Rp 0.2
N/mm2

nom. - 640 640 720 900 1080
min. - 640 660 720 940 1100
9 Stress
under
proffing

load, Sp

Sp/R
or
Sp/Rp 0.2
0,94 0,94 0,91 0,93 0,90 0,92 0,91 0,91 0.90 0,88 0,88
N/mm2 180 225 310 280 380 440 580 600 650 830 970
10 Bongation after
fracture A in % min.
min. 25 22 14 20 10 8 12 12 10 9 8
11 Strenght under
wedge loading
The values for full size bolts and screws (not studs) shall not be
smaller than the minimum values for tensile strength shown in 5.2
12 Impact
strength, J
min. - 25 - 30 30 25 20 15
13 Head soundness no fracture
14 Minimum height of non-decarbunzed - 1/2H1 2/3H1 3/4H1
15 Maximum depth of complete decarburization, G - 0.015
   

 for class 8.8 in diameter d<= 16 mm there is an increased risk of nut shipping in the case of inadvertent over-tightening
a load in acess of proofing load reference to ISO 898-2 is recomemded.

 For Structural boiling the limit is 12 mm
Applies only to nominal thread diameter d<=16 mm.
Min. tensile properties apply to products of nominal length I >=2,5 d. Min. Hardness applies to products of I < 2, 5 d and other products which can not be tensile tested(e.g. due to head configaration).
urface Hardness shall not be more than 30 vickers points above the measured core hardness on the product when readings of both surface and core are carried out at HV 0,3 for class 10.9 max. surface hardness = 390 HV
n cases where the lower yield stress R cannot be determined it is permissable to measure the proof stress R.
   
 
 
     

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