Hardening.—The forgings can be hardened by cooling in still air or quenching in oil or water from a temperature between 1,650 and 1,750°F.

The physical properties do not vary greatly when the carbon is within the range of composition given, or when the steel is hardened and tempered in air, oil, or water.

When used for valves the following specification of physical properties have been used:

Yield point, pounds per square inch70,000
Tensile strength, pounds per square inch90,000
Elongation in 2 in., per cent18
Reduction of area, per cent50

The usual heat treatment is to quench in oil from 1,650°F. and temper or draw at 1,100 to 1,200°F. One valve manufacturer stated that valves of this steel are hardened by heating the previously annealed valves to 1,650°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
C0.20
Mn0.45
Cr12.56
C0.27
Mn0.50
Cr12.24
C0.50
Cr14.84
Quenched in oil from degrees Fahrenheit 1,6001,600 1,650
Tempered at degrees Fahrenheit 1,1601,080 1,100
Yield point, pounds per square inch 78,30075,000 91,616
Tensile strength, pounds per square inch 104,600104,250 123,648
Elongation in 2 in., per cent 25.023.5 14.5
Reduction of area, per cent 52.551.4 33.5
TABLE 3.—COMPARISON OF PHYSICAL PROPERTIES BETWEEN AIR, OIL AND WATER-HARDENED STEEL HAVING CHEMICAL ANALYSIS IN PERCENTAGE OF
Carbon0.24
Manganese0.30
Phosphorus0.035
Sulphur0.035
Chromium12.85
Silicon0.20
Hardening medium Hardened from, degrees Fahrenheit Tempered at, degrees Fahrenheit Elastic limit, per lb. sq. in. Tensile strength, lb. per sq. in. Elongation in 2 in. per cent Reduction of area, per cent
Air 1,650 930 158,815 192,415 13.0 40.5
1,100 99,680 120,065 21.0 59.2
1,300 70,785 101,250 26.0 64.6
1,380 66,080 98,335 28.0 63.6
1,470 70,785 96,990 27.0 64.7
Oil 1,650 930 163,070 202,720 8.0 18.2
1,100 88,255 116,480 20.0 56.9
1,300 77,950 105,505 25.5 63.8
1,380 88,255 98,785 27.0 66.3
Water 1,650 930 158,815 202,050 12.0 34.2
1,100 90,270 120,735 22.0 59.8
1,300 66,080 102,590 25.8 64.8
1,380 67,200 97,890 27.0 65.2

This steel can be drawn into wire, rolled into sheets and strips and drawn into seamless tubes.

Corrosion.—This steel like any other steel when distorted by cold working is more sensitive to corrosion and will rust. Rough cut surfaces will rust. Surfaces finished with a fine cut are less liable to rust. Ground and polished surfaces are practically immune to rust.