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

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

Crucible Steel
Crucible steel is still made by melting material in a clay or...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

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

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

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

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

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

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

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...



Detrimental Elements






Category: HIGH-SPEED STEEL

Sulphur and phosphorus are two elements known
to be detrimental to all steels. Sulphur causes red-shortness
and phosphorus causes cold-shortness. The detrimental effects
of these two elements counteract each other to some extent but
the content should be not over 0.02 sulphur and 0.025 phosphorus.
The serious detrimental effect of small quantities of sulphur and
phosphorus is due to their not being uniformly distributed, owing
to their tendency to segregate.

The manganese and silicon contents are relatively unimportant in
the percentages usually found in high-speed steel.

The detrimental effects of tin, copper and arsenic are not generally
realized by the trade. Small quantities of these impurities are
exceedingly harmful. These elements are very seldom determined
in customers' chemical laboratories and it is somewhat difficult
for public chemists to analyze for them.

In justice to the manufacturer, attention should be called to the
variations in chemical analyses among the best of laboratories.
Generally speaking, a steel works' laboratory will obtain results
more nearly true and accurate than is possible with a customer's
laboratory, or by a public chemist. This can reasonably be expected,
for the steel works' chemist is a specialist, analyzing the same
material for the same elements day in and day out.

The importance of the chemical laboratory to a tool-steel plant
cannot be over-estimated. Every heat of steel is analyzed for each
element, and check analyses obtained; also, every substance used
in the mix is analyzed for all impurities. The importance of using
pure base materials is known to all manufacturers despite chemical
evidence that certain detrimental elements are removed in the process
of manufacture.

The manufacture of high-speed steel represents the highest art
in the making of steel by tool-steel practice. Some may say, on
account of our increased knowledge of chemistry and metallurgy,
that the making of such steel has ceased to be an art, but has
become a science. It is, in fact an art; aided by science. The
human element in its manufacture is a decided factor, as will be
brought in the following remarks:


The heat treatment of steel in its broad aspect may be said to
commence with the melting furnace and end with the hardening and
tempering of the finished product. High-speed steel is melted by
two general types of furnace, known as crucible and electric. Steel
treaters, however, are more vitally interested in the changes that
take place in the steel during the various processes of manufacture
rather than a detailed description of those processes, which are
more or less familiar to all.

In order that good high-speed steel may be furnished in finished
bars, it must be of correct chemical analysis, properly melted and
cast into solid ingots, free from blow-holes and surface defects.
Sudden changes of temperature are to be guarded against at every
stage of its manufacture and subsequent treatment. The ingots are
relatively weak, and the tendency to crack due to cooling strains
is great. For this reason the hot ingots are not allowed to cool
quickly, but are placed in furnaces which are of about the same
temperature and are allowed to cool gradually before being placed
in stock. Good steel can be made only from good ingots.

Steel treaters should be more vitally interested in the important
changes which take place in high-speed steel during the hammering
operations than that of any other working the steel receives in
the course of its manufacture.





Next: Quality And Structure

Previous: Standard Analysis



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