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Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Silicon
SILICON is a very widespread element (symbol Si), being an es...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

Hardening
Steel is hardened by quenching from above the upper critical....

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

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

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Chromium
Chromium when alloyed with steel, has the characteristic func...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...



Restoring Overheated Steel






Category: HARDENING CARBON STEEL FOR TOOLS

The effect of heat treatment on overheated steel is shown graphically
in Fig. 65 to the series of illustrations on pages 137 to 144. This
was prepared by Thos. Firth & Sons, Ltd., Sheffield, England.



The center piece Fig. 65 represents a block of steel weighing about
25 lb. The central hole accommodated a thermo-couple which was attached
to an autographic recorder. The curve is a copy of the temperature
record during heating and cooling. Into the holes in the side of
the block small pegs of overheated mild steel were inserted. One
peg was withdrawn and quenched at each of the temperatures indicated
by the numbered arrows, and after suitable preparation these pegs
were photographed in order to show the changes in structure taking
place during heating and cooling operations. The illustrations here
reproduced are selected from those photographs with the object
of presenting pictorially the changes involved in the refining of
overheated steel or steel castings.





Next: Hardening Carbon Steel For Tools

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