Steels_ Metallurgy and Applications, Third Edition

Low-carbon structural steels 159

1.5

E

r 1.0

8

300

Minimum YS (N/ram2)

0.5 I

200 400

Figure 2.12 Cost-yield strength relationships for plates (grades providing minimum
impact energy of 27 J at -20* C

Table 2.4

% Cot-Ten A Cot-Ten B Cot-Ten C

C 0.08 0.14 0.16

Si 0.50 0.20 0.20

Mn 0.25 1.10 1.20

P 0.11 0.04 max. 0.04 max.

Cr 0.75 0.50 0.50

Ni 0.35 - -

Cu 0.40 0.35 0.35

V - 0.06 0.07

The corrosion behaviour of these steels is shown in Figure 2.1312 where they
can be compared with plain carbon steel. Very clearly, the weathering grades
are superior to carbon steel in each of the atmospheres investigated, Cor-Ten A
providing a better performance than Cot-Ten B. However, in keeping with the
corrosion behaviour of other types of steel, the performance is worst in marine