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Steel Making

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

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

Critical Points
One of the most important means of investigating the properti...

A combination of the characteristics of nickel and the charac...

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

The material used for all gears on the Liberty engine was sel...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Martien was probably never a serious contender for the honor ...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

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

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

Piston Pin


The piston pin on an aviation engine must possess maximum resistance
to wear and to fatigue. For this reason, the piston pin is considered,
from a metallurgical standpoint, the most important part on the
engine to produce in quantities and still possess the above
characteristics. The material used for the Liberty engine piston
pin was S. A. E. No. 2315 steel, which is of the following chemical
composition: Carbon, 0.100 to 0.200 per cent; manganese, 0.500
to 0.800 per cent; phosphorus, 0.040 maximum per cent; sulphur,
0.045 maximum per cent; nickel, 3.250 to 3.750 per cent.

Each finished piston pin, after heat treatment, must show a minimum
scleroscope hardness of the case of 70, a scleroscope hardness of
the core of from 35 to 55 and a minimum crushing strength when
supported as a beam and the load applied at the center of 35,000
lb. The heat treatment used to obtain the above physical properties
consisted in carburizing at a temperature not to exceed 1,675 deg.F.,
for a sufficient length of time to secure a case of from 0.02 to
0.04 in. deep. The pins are then allowed to cool slowly from the
carbonizing heat, after which the hole is finish-machined and the
pin cut to length. The finish heat treatment of the piston pin
consisted in quenching in oil from a temperature of from 1,525 to
1,575 deg.F. to refine the grain of core properly and then quenching in
oil at a temperature of from 1,340 to 1,380 deg.F. to refine and harden
the grain of the case properly, as well as to secure proper hardness
of core. After this quenching, all piston pins are tempered in oil
at a temperature of from 375 to 400 deg.F. A 100 per cent inspection
for scleroscope hardness of the case and the core was made, and
no failures were ever recorded when the above material and heat
treatment was used.

Next: Application To The Automotive Industry

Previous: Crankshaft

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