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Steel Making

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

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

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

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

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

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Heating
Although it is possible to work steels cold, to an extent de...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

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

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

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

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

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

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...



Knowing What Takes Place






Category: HARDENING CARBON STEEL FOR TOOLS

How are we to know if we have given a
piece of steel the very best possible treatment?

The best method is by microscopic examination of polished and etched
sections, but this requires a certain expense for laboratory equipment
and upkeep, which may prevent an ordinary commercial plant from
attempting such a refinement. It is highly recommended that any
firm that has any large amount of heat treatment to do, install
such an equipment, which can be purchased for from $250 to $500.
Its intelligent use will save its cost in a very short time.

The other method is by examination of fractures of small test bars.
Steel heated to its correct temperatures will show the finest possible
grain, whereas underheated steel has not had its grain structure
refined sufficiently, and so will not be at its best. On the other
hand, overheated steel will have a coarser structure, depending
on the extent of overheating.

To determine the proper quenching temperature of any particular
grade of steel it is only necessary to heat pieces to various
temperatures not more than 20 deg.C. (36 deg.F.) apart, quench in water,
break them, and examine the fractures. The temperature producing
the finest grain should be used for annealing and hardening.

Similarly, to determine tempering temperatures, several pieces
should be hardened, then tempered to various degrees, and cooled
in air. Samples, say six, reheated to temperatures varying by 100 deg.
from 300 to 800 deg.C. will show a considerable range of properties,
and the drawing temperature of the piece giving the desired results
can be used.

For drawing tempers up to 500 deg.F. oil baths of fresh cotton seed
oil can be safely and satisfactorily used. For higher temperature
a bath of some kind of fused salt is recommended.





Next: Hints For Tool Steel Users

Previous: Temperatures To Use



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