(a) The tensile strength of the material shall conform to
one of the following four grades:-
(i) 37 to 45 kgf/mm2
(ii) 42 to 50 kgf/mm2
(iii) 47 to 56 kgf/mm2
(iv) 52 to 62 kgf/mm2
(b) The upper yield point at room temperature shall be not
less than 50% of the specified minimum tensile strength.
(c) The minimum values of the stress at proof limit 0.2%
at elevated temperature Et of the material may be calculated
by multiplying the minimum specified tensile strength at room
temperature R20 by the value of the ratio Et/R20 given in
the table under Regulation 16.
(d) The breaking elongation in percentage shall not be less
|Where, Rm =
Measured tensile strength at room temperature in kgf/mm2
93 = quality index
2.2 = a constant which is valid only when Lo = 5
Lo = gauge length.
do = original diameter of the round test