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forging-Sfcunping- Heaf Treating
January, 1925
S o m e Steel P r o b l e m s in t h e D r o p F o r g i n g
Industry*
Close Co-operation and Thorough Understanding Between Drop
Forger and Steel Producer Necessary to Meet Exist­
ing Demands of Consumer of Drop Forgings
By MARTIN H. SCHMIDf
IN this discussion 1 will make no attempt to describe to steel for forgings. and in such cases where the
how the steel manufacturer should make his forg­ product is purchased in the heat treated condition is
ing steel; neither will I attempt to tell the manu­ also accompanied by requirements as to physical charfacturer
of drop forgings how he should perform acteristics, or at least by hardness limits — usually
various operations about which he knows so much Brinell, Rockwell or Shore. When forgings are speci­
more than I. My objective is the consideration of fied according to chemical analysis alone it is reason­
certain conditions which are of mutual interest, and able to assume that your customer has selected such
a better understanding of which will avoid controversy chemistry range as will give, with satisfactory heat
and promote harmony between these great branches treatment, physical properties sufficiently high to
of industry.
meet stresses determined for the part or parts in ques­
During the past 10 or 15 years the progress in tion. In such instances where forgings are sold on
drop forging has been very rapid. The consumers of physical properties alone the manufacturer of forgings
your products, particularly the automotive manufac­ is confronted with the problem of selection of an
turers, have made increasingly difficult demands which analysis which will give the desired results in the fin­
have been met through your improvements in methods ished product at the lowest piece cost. He must con­
of fabrication and by your exacting demands from the sider the general characteristics of the material and
steel manufacturer. Fifteen years ago the steel manu­ his decision is influenced by uniformity of quality,
facturer met all requirements by furnishing products tendency toward inherent defects (both surface and
limited to a few standard analyses within liberal lim­ sub-surface), shearing quality, forgeability, scalage,
its, and free from pipe and seams. Now he is called response to heat treatment, machinability, etc. The
upon to meet restricted chemistry ranges, not only steel manufacturer should be able to offer sound sug­
freedom from pipe and seams but also segregation gestions for guidance on these points.
and the most minute external and internal imperfections.
Size restrictions, formerly considered impossible,
are now religiously adhered to. There are further
demands—the McOuaid-Ehn test, porosity and
fibre tests, microscopic examination, and looming on
the horizon are magnetic analysis and X-ray-
The closest co-operation and most thorough mutual
understanding will better enable us to satisfactorily
cope with your problems and our problems. The
steel manufacturer must exercise most rigid quality
control on his shipments of material for high grade
forgings. Quality, before being controlled, must first
be defined. Rigid inspection means but little if misdirected.
The steel maker must, by most intimate
contact with his customer, ascertain all details connected
with the requirements of material he is to furnish.
Much may be accomplished by a more comprehensive
understanding of details before filling orders.
Likewise, it is necessary for the manufacturer of forgings
to study in an exhaustive manner the precise requirements
of his trade. It is essential that inspection
be based upon practical knowledge of the application
of material in the customer's plant and that material
satisfactory for the purpose for which intended
not be needlessly rejected on minor technicalities.
Such is economic extravagance and waste.
Chemical Composition.
The primary consideration in ordering steels for
forgings is chemical range. In the majority of cases
this constitutes part of the specifications pertaining
Formerly there were but few analysis types to consider
in meeting a physical specification, but now there
are many types of steel, any of which can readily meet
imposed physical requirements. Production and manufacturing
problems are becoming more and more a
governing factor in the selection of analysis.
If specifications can be standardized to permit overlapping
ranges in carbon of one type of steel for various
parts it will work to the advantage of both buyer
and seller. On forgings for such parts as spindles,
arms, connecting rods, etc., .25 to .30 carbon may be
most satisfactory; for crankshafts, front axles, etc., .27
to .32 carbon preferable; and on shafts .32 to .37 carbon.
As long as reasonable quantities of material are
ordered in all three classifications the steel maker is
enabled to make selective application of heats to best
suit each and every requirement. In alloy steels this
selection should not be based on carbon content alone,
but clue consideration should also be given the various
alloying elements. It is evident that the making of
such specifications are but seldom in the hands of the
manufacturers of forgings—they should come from the
automotive and other manufacturers whom you supply
with forgings. But much may be accomplished if
both producers of forgings and of steel can influence
their customers to adopt this method. The result will
be a more uniform and superior finished product and
less contention in the making.
While the scope of this article will not permit detailed
consideration of the various types of allow steels
* Paper presented at a meeting of the American Drop there Forgare
two points on which I would like to briefly
ing Institute held at Pittsburgh. October 2 and 3. 1924. dwell—the five point range in carbon and the general
•^Metallurgical Engineer. United Alloy Steel Company. effect of several alloying elements.