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Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

Hardness Testing
The word hardness is used to express various properties of me...

Crucible Steel
Crucible steel is still made by melting material in a clay or...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Machineability
Reheating for machine ability was done at 100 deg. less than ...



Hardening






Category: ALLOYS AND THEIR EFFECT UPON STEEL

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.





Next: Corrosion

Previous: Annealing



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