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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Annealing Work
With the exception of several of the higher types of alloy s...

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

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

Hardening
The forgings can be hardened by cooling in still air or quen...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

Double Annealing
Water annealing consists in heating the piece, allowing it to...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

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

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Nickel-chromium
A combination of the characteristics of nickel and the charac...

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

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



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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