/ ,

^^^

\

/,

'

\

/.

^"

--

_J_

/

\

_l

\

__

~--

-^

]

C -J

'

W 3l

Iron Age

Fig. 109. Comparison of Different Kinds of Steel Containing 0.2 per cent Carbon, as shown by Tensile Tests on Specimens 100 mm. long and 13.8 mm. diameter. The Vertical Scale Represents Thousands of Poxmds per Square Inch and also Percentage of Contraction or Elongation

The heavy line shows ultimate strength

The dash line shows elastic limit

The dash-dot line shows percentage contraction

The light line shows percentage elongation

In this chart the thing of greatest interest is the contrast seen by comparing the shapes of the curves for different steels. Though it is best to have curves of such distinct shape plotted in separate fields, it is ordinarily most convenient to have the fields themselves placed vertically instead of horizontally

GRAPHIC METHODS

o < a m p* to ^ o '0 ft a ^ o <i f' a n o ^

S 8 £ a « 1 o

<u

COMPARISON OF CURVES

almost three times the height of the portion shown on this illustration, it would be necessary to make two other hinges in the horizontal extension so that the peak could be bent downward and turned backward from right to left, giving something of a spiral effect. Though this bent peak may seem rather artificial, it is quite certain that the

>

■*

(M

0)

r)

o

to

1901 1302 1903 19 04 1905 1906 1907 1908 1909 1310 19H