Here is a little tangle that is perpetually cropping up in various guises. A cyclist bought a bicycle for L15 and gave in payment a cheque for L25. The seller went to a neighbouring shopkeeper and got him to change the cheque for him, and the cycl... Read more of THE BICYCLE THIEF. at Math Puzzle.caInformational Site Network Informational
Privacy
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

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

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

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

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

Manganese
Manganese adds considerably to the tensile strength of steel,...

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

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

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

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

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

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

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

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

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

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

Nickel
Nickel may be considered as the toughest among the non-rare a...

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



Quenching Tool Steel






Category: HARDENING CARBON STEEL FOR TOOLS

To secure proper hardness, the cooling of quenching of steel is
as important as its heating. Quenching baths vary in nature, there
being a large number of ways to cool a piece of steel in contrast
to the comparatively few ways of heating it.

Plain water, brine and oil are the three most common quenching
materials. Of these three the brine will give the most hardness,
and plain water and oil come next. The colder that any of these
baths is when the piece is put into it the harder will be the steel;
but this does not mean that it is a good plan to dip the heated
steel into a tank of ice water, for the shock would be so great
that the bar would probably fly to pieces. In fact, the quenching
bath must be sometimes heated a bit to take off the edge of the
shock.

Brine solutions will work uniformly, or give the same degree of
hardness, until they reach a temperature of 150 deg.F. above which
their grip relaxes and the metals quenched in them become softer.
Plain water holds its grip up to a temperature of approximately
100 deg.F.; but oil baths, which are used to secure a slower rate of
cooling, may be used up to 500 deg. or more. A compromise is sometimes
effected by using a bath consisting of an inch or two of oil floating
on the surface of water. As the hot steel passes through the oil,
the shock is not as severe as if it were to be thrust directly
into the water; and in addition, oil adheres to the tool and keeps
the water from direct contact with the metal.

The old idea that mercury will harden steel more than any other
quenching material has been exploded. A bath consisting of melted
cyanide of potassium is useful for heating fine engraved dies and
other articles that are required to come out free from scale. One
must always be careful to provide a hood or exhaust system to get
rid of the deadly fumes coming from the cyanide pot.

The one main thing to remember in hardening tool steel is to quench
on a rising heat. This does not mean a rapid heating as a slow
increase in temperature is much better in every way.





Next: The Theory Of Tempering

Previous: Double Annealing



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 2878