Crankshaft
: APPLICATION OF LIBERTY ENGINE MATERIALS TO THE AUTOMOTIVE INDUSTRY: The Working Of Steel
The crankshaft was the most highly stressed part of the entire
Liberty engine, and, therefore, every metallurgical precaution
was taken to guarantee the quality of this part. The material used
for the greater portion of the Liberty crankshafts produced was
nickel-chromium steel of the following chemical composition: Carbon,
0.350 to 0.450 per cent; manganese, 0.300 to 0.600 per cent; phosphorus,
0.040 maximum per cent;
1.750 to 2.250 per cent; chromium, 0.700 to 0.900 per cent.
Each crankshaft was heat-treated to show the following minimum
physical properties: Elastic limit, 116,000 lb. per square inch;
elongation in 2 in., 16 per cent, reduction of area, 50 per cent,
Izod impact, 34 ft.-lb.; Brinell hardness, 266 to 321.
For every increase of 4,000 lb. per square inch in the elastic
limit above 116,000 lb. per square inch, the minimum Izod impact
required was reduced 1 ft.-lb.
The heat treatment used to produce these physical properties consisted
in normalizing the forgings at a temperature of from 1,550 to 1,600 deg.F.,
followed by quenching in water at a temperature of from 1,475 to
1,525 deg.F. and tempering at a temperature of from 1,000 to 1,100 deg.F.
It is absolutely necessary that the crankshafts be removed from the
quenching tank before being allowed to cool below a temperature of
500 deg.F., and immediately placed in the tempering furnace to eliminate
the possibility of quenching cracks.
A prolongation of not less than the diameter of the forging bearing
was forged on one end of each crankshaft. This was removed from
the shaft after the finish heat treatment, and physical tests were
made on test specimens which were cut from it at a point half way
between the center and the surface. One tensile test and one impact
test were made on each crankshaft, and the results obtained were
recorded against the serial number of the shaft in question. This
serial number was carried through all machining operations and
stamped on the cheek of the finished shaft. In addition to the
above tensile and impact tests, at least two Brinell hardness
determinations were made on each shaft.
All straightening operations on the Liberty crankshaft which were
performed below a temperature of 500 deg.F. were followed by retempering
at a temperature of approximately 200 deg.F. below the original tempering
temperature.
Another illustration of the importance of proper radii at all changes
of section is given in the case of the Liberty crankshaft. The presence
of tool marks or under cuts must be completely eliminated from an
aviation engine crankshaft to secure proper service. During the
duration of the Liberty program, four crankshafts failed from fatigue,
failures starting from sharp corners at bottom of propeller-hub
keyway. Two of the shafts that failed showed torsional spirals
running more than completely around the shaft. As soon as this
difficulty was removed no further trouble was experienced.
One of the most important difficulties encountered in connection
with the production of Liberty crankshafts was hair-line seams. The
question of hair-line seams has been discussed to greater length
by engineers and metallurgists during the war than any other single
question. Hair-line seams are caused by small non-metallic inclusions
in the steel. There is every reason to believe that these inclusions
are in the greater majority of cases manganese sulphide. There is
a great difference of opinion as to the exact effect of hair-line
seams on the service of an aviation engine crankshaft. It is the
opinion of many that hair-line seams do not in any way affect the
endurance of a crankshaft in service, provided they are parallel to
the grain of the steel and do not occur on a fillet. Of the 20,000
Liberty engines produced, fully 50 per cent of the crankshafts
used contain hair-line seams but not at the locations mentioned.
There has never been a failure of a Liberty crankshaft which could
in any way be traced to hair-line seams.
It was found that hair-line seams occur generally on high
nickel-chromium steels. One of the main reasons why the comparatively
mild analysis nickel-chromium steel was used was due to the very
few hair-line seams present in it. It was also determined that
the hair lines will in general be found near the surface of the
forgings. For that reason, as much finish as possible was allowed
for machining. A number of tests have been made on forging bars
to determine the depths at which hair-line seams are found, and
many cases came up in which hair-line seams were found 3/8 in.
from the surface of the bar. This means that in case a crankshaft
does not show hair-line seams on the ground surface this is no
indication that it is free from such a defect.
One important peculiarity of nickel-chromium steel was brought
out from the results obtained on impact tests. This peculiarity
is known as blue brittleness. Just what the effect of this is
on the service of a finished part depends entirely upon the design
of the particular part in question. There have been no failures of
any nickel-chromium steel parts in the automotive industry which
could in any way be traced to this phenomena.
Whether or not nickel-chromium-steel forgings will show blue
brittleness depends entirely upon the temperature at which they
are tempered and their rate of cooling from this temperature. The
danger range for tempering nickel-chromium steels is between a
temperature of from 400 to 1,100 deg.F. From the data so far gathered
on this phenomena, it is necessary that the nickel-chromium steel
to show blue brittleness be made by the acid process. There has
never come to my attention a single instance in which basic open
hearth steel has shown this phenomena. Just why the acid open hearth
steel should be sensitive to blue brittleness is not known.
All that is necessary to eliminate the presence of blue brittleness
is to quench all nickel-chromium-steel forgings in water from their
tempering temperature. The last 20,000 Liberty crankshafts that
were made were quenched in this manner.
More
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Annealing
ANNEALING can be done by heating to temperatures ranging from 1,290 to 1,380 deg.F. and cooling in air or quenching in water or oil. After this treatment the forgings will have a hardness of about 200 Brinell and a tensile strength of 100,000 to 112... Annealing
There is no mystery or secret about the proper annealing of different steels, but in order to secure the best results it is absolutely necessary for the operator to know the kind of steel which is to be annealed. The annealing of steel is primarily ... Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, refers largely to nickel and chromium steel or a combination of both. These steels are manufactured very largely by the open-hearth process, although chromium steels are also a crucible pro... Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. Pack the work the same as for case-hardening except that it is not necessary to keep the pieces away from each other. Pack with bone that has been used until it is nearly white. Heat as ho... Annealing Method
Forgings which are too hard to machine are put in pots with a little charcoal to cause a reducing atmosphere and to prevent scale. The covers are then luted on and the pots placed in the furnace. Carbon steel from 15 to 25 points is annealed at 1,6... Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using ground mica, charcoal, lime, fine dry ashes or lake sand as a packing in the annealing boxes. Mixtures of one part charcoal, one part lime and three parts of sand are also suggested, or two... Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufactured at the Armory and all forgings for other ordnance establishments are packed in charcoal, lime or suitable material and annealed before being transferred from the forge shop. Exce... Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempered will, if complex in shape, contain many internal stresses which may later cause it to break. They may be eased off by slight heating without materially lessening the hardness of the pi... Annealing Work
With the exception of several of the higher types of alloy steels, where the percentages of special elements run quite high, which causes a slight air-hardening action, the carburizing steels are soft enough for machining when air cooled from any t... Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineering achievement in which the science of metallurgy played an important part. The reasons for the use of certain materials and certain treatments for each part are given with recommendation... Application To The Automotive Industry
The information given on the various parts of the Liberty engine applies with equal force to the corresponding parts in the construction of an automobile, truck or tractor. We recommend as first choice for carbon-steel screw-machine parts material p... Bessemer Process
The bessemer process consists of charging molten pig iron into a huge, brick-lined pot called the bessemer converter, and then in blowing a current of air through holes in the bottom of the vessel into the liquid metal. The air blast burns the wh... Blending The Compound
Essentially, this consists of the sturdy, power-driven separator and fanning mill which separates the foreign matter from the compound and elevates it into a large settling basin which is formed by the top of the steel housing that incloses the appa... Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to maintain an operator at a central pyrometer, and by colored electric lights at the furnaces, signal whether the temperatures are correct or not. It is common practice to locate three lights abov... Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one which does not necessitate the use of an expensive laboratory equipment is that based upon determining the melting point of common table salt (sodium chloride). While theoretically salt that ... Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, usually contains from 80 to 125 points (or from 0.80 to 1.25 per cent) of carbon, and none of the alloys which go to make up the high speed steels. This was formerly known also as crucible o... Carbon Steels For Different Tools
All users of tool steels should carefully study the different qualities of the steels they handle. Different uses requires different kinds of steel for best results, and for the purpose of designating different steels some makers have adopted the tw... Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not hammer steel when it cools down to a dark cherry red, or just below its hardening point, as this creates surface cracks. ... Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as carbureter control levers, etc. The important criterion for parts of this type is ease of fabrication and freedom from over-heated and burned forgings. The material used for such parts was S.... Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page 88, consists of having a slowly revolving, properly heated, cylindrical retort into which illuminating gas (a mixture of various hydrocarbons) is continuously injected under pressure. The ... Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-iron differential-case hubs. Formerly, these sleeves were given two treatments after carburization in order to refine the case and the core, and then sent to the grinding department, where t... Carburizing Material
The simplest carburizing substance is charcoal. It is also the slowest, but is often used mixed with something that will evolve large volumes of carbon monoxide or hydrocarbon gas on being heated. A great variety of materials is used, a few of them ... 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 an... Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most common quenching materials for case-hardening. Water is used for ordinary work, salt water for work which must be extremely hard on the surface, and oil for work in which toughness is the ma... Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on the percentage of each element contained in the steel. Steel containing from 1/2 to 1 per cent chromium and from 1-1/2 to 3-1/2 per cent nickel, with a carbon content equal to the chromium... Chromium
Chromium when alloyed with steel, has the characteristic function of opposing the disintegration and reconstruction of cementite. This is demonstrated by the changes in the critical ranges of this alloy steel taking place slowly; in other words, it ... Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by grade and temper. The word grade is qualified by many adjectives of more or less cryptic meaning, but in general they aim to denote the process and care with which the steel is made. Tem... Compensating Leads
By the use of compensating leads, formed of the same material as the thermo-couple, the cold junction can be removed from the head of the thermo-couple to a point 10, 20 or 50 ft. distant from the furnace, where the temperature is reasonably consta... Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown electromotive force, the new couple may be checked against a standard instrument, placing the two bare couples side by side in a suitable tube and taking frequent readings over the range of... Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen text books on metallurgy and not find a definition of the word steel. Some of them describe the properties of many other irons and then allow you to guess that everything else is steel. If it... Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the percentage of chromium raised slightly, an ideal transmission-gear material is obtained. This would, therefore, be of the following composition: Carbon, 0.470 to 0.520 per cent; manganese, 0... Conclusions
Martien was probably never a serious contender for the honor of discovering the atmospheric process of making steel. In the present state of the record, it is not an unreasonable assumption that his patent was never seriously exploited and that the ... Connecting Rods
The material used for all connecting rods on the Liberty engine was selected at the option of the manufacturer from one of two standard S. A. E. steels, the composition of which are given in Table 13. TABLE 13.--COMPOSITION OF STEELS NOS. X-3,335... Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means of which the pointer can be set to any actual cold-junction temperature. If the cold junction of the thermo-couple is in a temperature of 100 deg.F., the pointer can be set to this point o... Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrometer is dependent on the difference in temperature between its hot junction, inside the furnace, and the cold junction, or opposite end of the thermo-couple to which the copper wires are c... Corrosion
This steel like any other steel when distorted by cold working is more sensitive to corrosion and will rust. Rough cut surfaces will rust. Surfaces finished with a fine cut are less liable to rust. Ground and polished surfaces are practically immune... Crankshaft
The crankshaft was the most highly stressed part of the entire Liberty engine, and, therefore, every metallurgical precaution was taken to guarantee the quality of this part. The material used for the greater portion of the Liberty crankshafts produ... Critical Points
One of the most important means of investigating the properties of pure metals and their alloys is by an examination of their heating and cooling curves. Such curves are constructed by taking a small piece and observing and recording the temperature... Crucible Steel
Crucible steel is still made by melting material in a clay or graphite crucible. Each crucible contains about 40 lb. of best puddled iron, 40 lb. of clean mill scrap--ends trimmed from tool steel bars--and sufficient rich alloys and charcoal to make... Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw, milling cutter or circular saw. Cut clear through the bar; do not nick or break. To cut a piece from an unannealed bar, cut right off with an abrasive saw; do not nick or break. If of lar... Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. With this bath, the heat can be controlled within 3 deg. The steel is evenly heated without exposure to the air, resulting in work which is not warped and on which there is no scale. The cya... Detrimental Elements
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 sho... Double Annealing
Water annealing consists in heating the piece, allowing it to cool in air until it loses its red heat and becomes black and then immediately quenching it in water. This plan works well for very low-carbon steel; but for high-carbon steel what is kno... Drop Forging Dies
The kind of steel used in the die of course influences the heat treatment it is to receive, but this also depends on the kind of work the die is to perform. If the die is for a forging which is machined all over and does not have to be especially cl... Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Bessemer had received applications from several ironmasters for licenses, which were issued in return for a down payment and a nominal royalty of 25 pence per ton. Among those who started negotia... Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Johnston on two types of steel: one containing 0.30 per cent carbon, 0.012 per cent phosphorus, and 0.860 per cent copper, and the other 0.365 per cent carbon, 0.053 per cent phosphorus, and ... Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different packing materials has a different effect upon the work in which it is heated. Charcoal by itself will give a rather light case. Mixed with raw bone it will carburize more rapidly, and still... Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solution or combination to take place between the ferrite and pearlite, producing a homogeneous mass of small grains of each, the grains of the pearlite being surrounded by grains of ferrite. ... Fatigue Tests
It has been known for fifty years that a beam or rod would fail at a relatively low stress if only repeated often enough. It has been found, however, that each material possesses a limiting stress, or endurance limit, within which it is safe, no mat... Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 106 may prove serviceable before furnaces required for plate work, where the doors are often only opened for a moment at a time. This shield can be placed far enough in front of the furnace... For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a pipe, box or muffle. Arrange the steel so as to allow at least 1 in. of packing, consisting of dry powder ashes, powdered charcoal, mica, etc., between the pieces and the walls of the box ... Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F. and forge thoroughly and uniformly. If the forging operation is prolonged do not continue forging the tool when the steel begins to stiffen under the hammer. Do not forge below 1,700 deg.F... Furnace Data
In order to give definite information concerning furnaces, fuels etc., the following data is quoted from a paper by Seth A. Moulton and W. H. Lyman before the Steel Heat Treaters Society in September, 1920. This considers a factory producing 30,0... Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for carburizing have been generally recognized in the past from points of view as close temperature regulation, decreased attendance, and greater convenience, very little information has been ... Gears
The material used for all gears on the Liberty engine was selected at the option of the manufacturer from the following standard S. A. E. steels, the composition of which are given in Table 12, TABLE 12.--COMPOSITION OF STEELS NOS. X-3,340 AND 6,1... Hardening
The forgings can be hardened by cooling in still air or quenching in oil or water from a temperature between 1,650 and 1,750 deg.F. The physical properties do not vary greatly when the carbon is within the range of composition given, or when the ... Hardening
Steel is hardened by quenching from above the upper critical. Apparently the quick cooling prevents the normal change back to definite and sizeable crystals of ferrite and cementite. Hardness is associated with this suppressed change. If the change ... Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of steel wanted for shop tools, he generally made his own designs, hardened, tempered, ground and usually set up the machine where it was to be used and tested it. Most of us remember the to... Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly and thoroughly to a lemon heat. Do not forge at a lower heat. Do not let the steel cool below a bright cherry red while forging. After the tool is dressed, reheat to forging heat to remove... Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels. The most ordinary tools used are for lathes and planers. The forging should be done at carbon-steel heat. Rough-grind while still hot and preheat to about carbon-steel hardening heat, th... Hardening Operation
Hardening a gear is accomplished as follows: The gear is taken from the furnace by the furnaceman and placed in the lower die, surrounding the centering jaws, as shown at H in Fig. 62 and C in Fig. 63. Air is then turned into the cylinder D, and th... Hardness Testing
The word hardness is used to express various properties of metals, and is measured in as many different ways. Scratch hardness is used by the geologist, who has constructed Moh's scale as follows: Talc has a hardness of 1 Rock Salt h... Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the following minimum physical properties: Elastic limit, 115,000 lb. per square inch; elongation in 2 in., 16 per cent; reduction of area, 50 per cent; Brinell hardness, 277 to 321. The h... Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gear Manufacturers' Association at White Sulphur Springs, W. Va., Apr. 18, 1918. Great advancement has been made in the heat treating and hardening of gears. In this advancement the chemic... Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundry coke, broken in small pieces, in an ordinary blacksmith forge with a few bricks laid over the top to form a hollow fire. The bricks should be thoroughly heated before tools are heated. H... Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats are now made for treating high-speed steels. We recommend them for treating all kinds of Blue Chip tools and particularly the above class. After tools reach a yellow heat in the forge fire... Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes should be heated depends upon the shape, size and use for which they are intended. Generally, they should not be heated to quite as high a heat as lathe tools or milling cutters. They should h... Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at definite rates in order to change its physical condition. Many objects may be attained by correct heat treatment, but nothing much can be expected unless the man who directs the operations know... Heat-treating Department
The heat-treating department occupies an L-shaped building. The design is very practical, with the furnace and the floor on the same level so that there is no lifting of heavy pots. Fuel oil is used in all the furnaces and gives highly satisfactory... Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company, Syracuse, N. Y., runs day and night, and besides handling all the hardening of tools, parts of jigs, fixtures, special machines and appliances, carburizes and heat-treats every month bet... Heating
Although it is possible to work steels cold, to an extent depending upon their ductility, and although such operations are commonly performed, forging usually means working heated steel. Heating is therefore a vital part of the process. Heating s... Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used for the heating of manganese and other alloy steels, which after having been brought to the proper heat are drawn from the furnace into an immediate quenching tank. With manganese steel in...