Properties Of Steel
:
COMPOSITION AND PROPERTIES OF STEEL
:
The Working Of Steel
Steels are known by certain tests. Early tests were more or less
crude, and depended upon the ability of the workman to judge the
grain exhibited by a freshly broken piece of steel. The cold-bend
test was also very useful--a small bar was bent flat upon itself,
and the stretched fibers examined for any sign of break. Harder
stiff steels were supported at the ends and the amount of central
load they would support before
fracture, or the amount of permanent
set they would acquire at a given load noted. Files were also used
to test the hardness of very hard steel.
These tests are still used to a considerable extent, especially in
works where the progress of an operation can be kept under close
watch in this way, the product being periodically examined by more
precise methods. The chief furnace-man, or melter, in a steel
plant, judges the course of the refining process by casting small
test ingots from time to time, breaking them and examining the
fracture. Cutlery manufacturers use the bend test to judge the
temper of blades. File testing of case-hardened parts is very common.
However there is need of standardized methods which depend less
upon the individual skill of the operator, and which will yield
results comparable to others made by different men at different
places and on different steels. Hence has grown up the art of testing
materials.