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Steel Making

The Modern Hardening Room
A hardening room of today means a very different place from ...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

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

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

Furnace Data
In order to give definite information concerning furnaces, fu...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Care In Annealing
Not only will benefits in machining be found by careful anne...

Annealing
There is no mystery or secret about the proper annealing of d...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

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

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...



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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