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Steel Making

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Conclusions
Martien was probably never a serious contender for the honor ...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

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...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

The Influence Of Size
The size of the piece influences the physical properties obta...

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

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

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

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



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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