Informational Site NetworkInformational Site Network
Privacy
 
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

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

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

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

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

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

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

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

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

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

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

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

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

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

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

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...



Care In Annealing






Category: HEAT TREATMENT OF STEEL

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 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 3243