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Indicated stresses in Newton/mm^{2}
Strength Designation  3.6  4.6  4.8  5.6  5.8  6.8  8.8 =< 16mm 
8.8 > 16 
9.8  10.9  12.9 
Nom. Tensile Strength  300  400  400  500  500  600  800  800  900  1000  1200 
Min Tensile Strength  330  400  420  500  520  600  800  830  900  1000  1200 
Lower Yield Stress  180/190  240  320/340  300  400/420  480           
Stress at Perm. Set              640  640/660  720  900/940  1080/100 
In accordance with BS 3692:2001 and BS EN IOS 8981 : 1999
Tensile Strength Of Metric NutsIndicated stresses in Newton/mm^{2}
Strength Designation  4  5  6  8  10  12 
Tensile Strength  400  500  600  800  1000  1200 
In accordance with BS 3692:2001
The designation system allows the determination of the ultimate and yield/proof strength of
the bolt. The designation system is based on two numbers e.g 8.8 . The first number is
the tensile strength of the bolt material (N^{2} )/100. The second number is
= 1/100.(the ratio of the Proof (or Yield ) stress and the Tensile strength expressed
as a percentage = 100.[Yield (Proof stress) /Tensile strength] /100
The tensile and proof strength of the steel for a 4.6 bolt is therefore calculated
as follows
Tensile strength (R_{m}) = 4.100 N/mm^{2} = 400 N/mm^{2} .... Proof strength (R_{0,2}) = 0,6*400 * 100 /100 = 240 N/mm^{2}
Stainless steels include Austenitic, Martensitic and Ferritic..
Austenitic stainless steels..
Chromium nickel steels which can be cold worked. Non magnetic.
Associated grades ( Steel Number according to BS EN 10088 pt 1) = A1 (1.4305) ,
A2 (1.4301) ,A3 (1.4541) , A4 (1.4401) and A5 (1.4571).
Martensitic stainless steels ..
Limited corrosion resistance but can be heat treated for superior strength properties. Magnetic Properties.
Associated grades ( Steel Number according to BS EN 10088 pt 1) = C1 (1.4006 etc) , C3 (1.4057), C4(1.4104)
Ferritic stainless steels ..
Plain chromium stainless steels with a chromium content varying between 10.5
and 18% and a low carbon content. They not hardenable by heat treatment.
Ferritic alloys have good ductility and formability but a relatively poor high
temperature strength compared austenitic grades. Magnetic..
Associated grades = F1
Indicated stresses in Newton/mm^{2}
Stainless Steel  Austenitic  Martensitic  Ferritic  
Steel Grade  A1, A2, A3, A4, A5  C1,C4  C1  C3  F1  
Strength class  50  70  80  100  50  70  110  80  45  60 
Tensile Strength  500  700  800  1000  500  700  1100  800  450  600 
0,2% proof stress  210  450  600  750  250  410  820  640  250  410 
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Last Updated 24/01/2013