- What Is The Human Aura? What do the different colors represent? Visit Auras.caInformational Site Network Informational
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

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

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

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

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

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

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

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

Sulphur is another impurity and high sulphur is even a greate...

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

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...

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

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

Care In Annealing


Not only will benefits in machining be found
by careful annealing of forgings but the subsequent troubles in
the hardening plant will be greatly reduced. The advantages in
the hardening start with the carburizing operation, as a steel of
uniform and fine grain size will carburize more uniformly, producing
a more even hardness and less chances for soft spots. The holes in
the gears will also close in more uniformly, not causing some
gears to require excessive grinding and others with just enough
stock. Also all strains will have been removed from the forging,
eliminating to a great extent distortion and the noisy gears which
are the result.

With the steels used, for the heat-treated gears, always of a higher
carbon content, treatment after forging is necessary for machining, as
it would be impossible to get the required production from untreated
forgings, especially in the alloy steels. The treatment is more
delicate, due to the higher percentage of carbon and the natural
increase in cementite together with complex carbides which are
present in some of the higher types of alloys.

Where poor machining conditions in heat-treated steels are present
they are generally due to incomplete solution of cementite rather
than bands of free ferrite, as in the case of case-hardening steels.
This segregation of carbon, as it is sometimes referred to, causes
hard spots which, in the forming of the tooth, cause the cutter
to ride over the hard metal, producing high spots on the face of
the tooth, which are as detrimental to satisfactory gear cutting
as the drops or low spots produced on the face of the teeth when
the pearlite is coarse-grained or in a banded condition.

In the simpler carburized steels it is not necessary to test the
forgings for hardness after annealing, but with the high percentages
of alloys in the carburizing steels and the heat-treated steels
a hardness test is essential.

To obtain the best results in machining, the microstructure of the
metal should be determined and a hardness range set that covers
the variations in structure that produce good machining results.
By careful control of the heat-treating operation and with the aid
of the Brinell hardness tester and the microscope it is possible
to continually give forgings that will machine uniformly and be
soft enough to give desired production. The following gives a few
of the hardness numerals on steel used in gear manufacture that
produce good machining qualities:

0.20 per cent carbon, 3 per cent nickel, 1-1/4; per cent
chromium--Brinell 156 to 170.

0.50 per cent carbon, 3 per cent nickel, 1 per cent chromium--Brinell
179 to 187.

0.50 per cent carbon chrome-vanadium--Brinell 170 to 179.

Next: The Influence Of Size

Previous: Temperature For Annealing

Add to Add to Reddit Add to Digg Add to Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network

Viewed 3046