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 deg.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 inch 70,000

Tensile strength, pounds per square inch 90,000

Elongation in 2 in., per cent 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,ElongationReduction

medium degrees at, degrees per lb. lb. Per in 2 in. of area,

FahrenheitFahrenheit 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

Air 1,650 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

-------------------------------------------------------------------

930 163,070 202,720 8.0 18.2

Oil 1,650 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

-------------------------------------------------------------------

930 158,815 202,050 12.0 34.2

Water 1,650 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.





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