18
Reduction of area, per cent 50

The usual heat treatment is to quench in oil from 1,650 deg.F. and
temper or draw at 1,100 to 1,200 deg.F. One valve manufacturer stated
that valves of this steel are hardened by heating the previously
annealed valves to 1,650 deg.F. and cooling in still air. This treatment
gives a scleroscope hardness of about 50.

In addition to use in valves this steel should prove very satisfactory
for shafting for water-pumps and other automobile parts subject to
objectionable corrosion.

TABLE 2.--COMPARISON OF PHYSICAL PROPERTIES FOR HIGH-CHROMIUM
STEELS OF DIFFERENT CARBON CONTENT --------------------------------------------------------------------------
| C 0.20 | C 0.27 | C 0.50
| Mn 0.45 | Mn 0.50 |
| Cr 12.56 | Cr 12.24 | Cr 14.84
-----------------------------------------|----------|----------|----------
Quenched in oil from degrees Fahrenheit | 1,600 | 1,600 | 1,650
Tempered at degrees Fahrenheit | 1,160 | 1,080 | 1,100
Yield point, pounds per square inch | 78,300 | 75,000 | 91,616
Tensile strength, pounds per square inch | 104,600 | 104,250 | 123,648
Elongation in 2 in., per cent | 25.0 | 23.5 | 14.5
Reduction of area, per cent | 52.5 | 51.4 | 33.5
--------------------------------------------------------------------------

TABLE 3.--COMPARISON OF PHYSICAL PROPERTIES BETWEEN AIR, OIL AND
WATER-HARDENED STEEL HAVING CHEMICAL ANALYSIS IN
PERCENTAGE OF
-------------------------------------------------------------------------
Carbon 0.24
Manganese 0.30
Phosphorus 0.035
Sulphur 0.035
Chromium 12.85
Silicon 0.20

-------------------------------------------------------------------------
| Hardened | | Elastic | Tensile | |
Hardening| from, | Tempered | limit, |strength,|Elongation|Reduction
medium | degrees |at, degrees| per lb. |lb. Per | in 2 in. |of area,
|Fahrenheit|Fahrenheit | sq. in. | sq. in. | per cent |per cent
---------|----------|-----------|---------|---------|----------|---------
| | 930 | 158,815 | 192,415 | 13.0 | 40.5
| | 1,100 | 99,680 | 120,065 | 21.0 | 59.2