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Steel Making

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

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

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

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

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

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

Hardness Testing
The word hardness is used to express various properties of me...

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

Quenching
It is considered good practice to quench alloy steels from th...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...



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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