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Steel Making

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

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

Silicon
SILICON is a very widespread element (symbol Si), being an es...

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

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

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

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

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...



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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