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Steel Making

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Silicon prevents, to a large extent, defects such as gas bubb...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

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

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Critical Points
One of the most important means of investigating the properti...

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

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

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

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

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Refining The Grain


This is remedied by reheating the piece to a temperature slightly
above the critical temperature of the case, this temperature
corresponding ordinarily to that of steel having a carbon content
of 85 points, When this is again quenched, the temperature, which
has not been high enough to disturb the refined core, will have
closed the grain of the case and toughened it. So, instead of but
one heat and one quenching for this class of work, we have three
of each, although it is quite possible and often profitable to
omit the quenching after carburizing and allow the piece or pieces
and the case-carburizing box to cool together, as in annealing.
Sometimes another heat treatment is added to the foregoing, for
the purpose of letting down the hardness of the case and giving
it additional toughness by heating to a temperature between 300 deg.
and 500 deg.. Usually this is done in an oil bath. After this the piece
is allowed to cool.

It is possible to harden the surface of tool steel extremely hard
and yet leave its inner core soft and tough for strength, by a
process similar to case-hardening and known as pack-hardening.
It consists in using tool steel of carbon contents ranging from
60 to 80 points, packing this in a box with charred leather mixed
with wood charcoal and heating at a low-red heat for 2 or 3 hr.,
thus raising the carbon content of the exterior of the piece. The
article when quenched in an oil bath will have an extremely hard
exterior and tough core. It is a good scheme for tools that must
be hard and yet strong enough to stand abuse. Raw bone is never
used as a packing for this class of work, as it makes the cutting
edges brittle.

Next: Case-hardening Treatments For Various Steels

Previous: The Quenching Tank

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