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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

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

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

The Thermo-couple
With the application of the thermo-couple, the measurement of...

Annealing
ANNEALING can be done by heating to temperatures ranging from...

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

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

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

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...

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

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

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

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...



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.





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Previous: Temperatures To Use



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