VIEW THE MOBILE VERSION of www.steelmaking.ca Informational Site Network Informational
Privacy
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

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

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Annealing
There is no mystery or secret about the proper annealing of d...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

The Modern Hardening Room
A hardening room of today means a very different place from ...

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

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

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

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

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

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

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

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

Drop Forging Dies
The kind of steel used in the die of course influences the he...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...



The Theory Of Tempering






Category: HARDENING CARBON STEEL FOR TOOLS

Steel that has been hardened is generally
harder and more brittle than is necessary, and in order to bring
it to the condition that meets our requirements a treatment called
tempering is used. This increases the toughness of the steel, i.e.,
decrease the brittleness at the expense of a slight decrease in
hardness.

There are several theories to explain this reaction, but generally
it is only necessary to remember that in hardening we quench steel
from the austenite phase, and, due to this rapid cooling, the normal
change from austenite to the eutectoid composition does not have
time to take place, and as a consequence the steel exists in a
partially transformed, unstable and very hard condition at atmospheric
temperatures. But owing to the internal rigidity which exists in
cold metal the steel is unable to change into its more stable phase
until atoms can rearrange themselves by the application of heat.
The higher the heat, the greater the transformation into the softer
phases. As the transformation takes place, a certain amount of heat
of reaction, which under slow cooling would have been released in
the critical range, is now released and helps to cause a further
slight reaction.

If a piece of steel is heated to a certain temperature and held
there, the tempering color, instead of remaining unchanged at this
temperature, will advance in the tempering-color scale as it would
with increasing temperature. This means that the tempering colors
do not absolutely correspond to the temperatures of steels, but the
variations are so slight that we can use them in actual practice.
(See Table 23, page 158.)





Next: Temperatures To Use

Previous: Quenching Tool Steel



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK


Viewed 4219