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Steel Making

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

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...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

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

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

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

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

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

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

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

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

Corrosion
This steel like any other steel when distorted by cold worki...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

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

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



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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