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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

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

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

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

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

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

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

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

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

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

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

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Nickel-chromium
A combination of the characteristics of nickel and the charac...



Liberty Motor Connecting Rods






Category: ALLOYS AND THEIR EFFECT UPON STEEL

The requirements for materials for the Liberty motor connecting rods
are so severe that the methods of securing the desired qualities
will be of value in other lines. The original specifications called
for chrome-nickel but the losses due to the difficulty of handling
caused the Lincoln Motor Company to suggest the substitution of
chrome-vanadium steel, and this was accepted by the Signal Corps. The
rods were accordingly made from chromium-vanadium steel, containing
carbon, 0.30 to 0.40 per cent; manganese, 0.50 to 0.80 per cent;
phosphorus, not over 0.04 per cent; sulphur, not over 0.04 per
cent; chromium, 0.80 to 1.10 per cent; vanadium, not less than 0.15
per cent. This steel is ordinarily known in the trade as 0.35 carbon
steel, S. A. E., specification 6,135, which provides a first-rate
quality steel for structural parts that are to be heat-treated.
The fatigue resisting or endurance qualities of this material are
excellent. It has a tensile strength of 150,000 lb. minimum per
square inch; elastic limit, 115,000 lb. minimum per square inch;
elongation, 5 per cent minimum in 2 in.; and minimum reduction
in area, 25 per cent.

The original production system as outlined for the manufacturers
had called for a heat treatment in the rough-forged state for the
connecting rods, and then semi-machining the rod forgings before
giving them the final treatment. The Lincoln Motor Company insisted
from the first that the proper method would be a complete heat
treatment of the forging in the rough state, and machining the
rod after the heat treatment. After a number of trial lots, the
Signal Corps acceded to the request and production was immediately
increased and quality benefited by the change. This method was
later included in a revised specification issued to all producers.

The original system was one that required a great deal of labor
per unit output. The Lincoln organization developed a method of
handling connecting rods whereby five workmen accomplished the
same result that would have required about 30 or 32 by the original
method. Even after revising the specification so as to allow complete
heat treatments in the rough-forged state, the ordinary methods
employed in heat-treating would have required 12 to 15 men. With
the fixtures employed, five men could handle 1,300 connecting rods,
half of which are plain and half, forked, in a working period of
little over 7 hr.




The increase in production was gained by devising fixtures which
enabled fewer men to handle a greater quantity of parts with less
effort and in less time.

In heat-treating the forgings were laid on a rack or loop A,
Fig. 14, made of 1-1/4-in. double extra-heavy pipe, bent up with
parallel sides about 9 in. apart, one end being bent straight across
and the other end being bent upward so as to afford an easy grasp
for the hook. Fifteen rods were laid on each loop, there being
four loops of rods charged into a furnace with a hearth area of 36
by 66 in. The rods were charged at a temperature of approximately
900 deg.F. They were heated for refining over a period of 3 hr. to
1,625 deg.F., soaked 15 min, at this degree of heat and quenched in
soluble quenching oil.

In pulling the heat to quench the rods, the furnace door was raised
and the operator pulls one of the loops A, Fig. 15 forward to
the shelf of the furnace, supporting the straight end of the loop
by means of the porter bar B. They swung the loop of rods around
from the furnace shelf and set the straight end of the loop on
the edge of the quenching tank, then raise the curved end C,
by means of their hook D so that all the rods on the loop slide
into the oil bath.

Before the rods cooled entirely, the baskets in the quenching tank
were raised and the oil allowed to partly drain off the forgings,
and they were stacked on curved-end loops or racks and charged into
the furnace for the second or hardening heat. The temperature of
the furnace was raised in 1-1/2 hr. to 1,550 deg.F., the rods soaked
for 15 min. at this degree of heat and quenched in the same manner
as above.

They were again drained while yet warm, placed on loops and charged
into the furnace for the third or tempering heat. The temperature of
the furnace was brought to 1,100 deg.F. in 1 hr., and the rods soaked at
this degree of heat for 1 hr. They were then removed from the furnace
the same as for quenching, but were dumped onto steel platforms
instead of into the quenching oil, and allowed to cool on these
steel platforms down to the room temperature.





Next: Pickling The Forgings

Previous: Corrosion



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