| When I came to
the McKenna Company in March, 1898, steel rails were being manufactured
by the Bessemer process, but the Open Hearth process was superceding
it. Some rail joints were being made by the Sellers Manufacturing
Company out of puddled wrought iron, but the large steel companies were
following the general trend of Open Hearth succeeding Bessemer. |
| Railroads were
having trouble with railroad rails, battered at the joints, which made
rough riding. Some railroads removed these rails, cut the ends
off at cold-sawing plants, drilled new bolt-holes, and then relaid the
rails in track. Some railroads used the battered rails in
secondary track or sold them to independent mills where they were
rolled into concrete rods and other products. The various
treatments or worn rails were a more or less thriving business. |
| Then came the
McKenna process of "renewing" worn rails by heating the worn rails and
putting them through two passes of rolls which reshaped the worn parts
and elongated the rails enough to saw off the worn rails at the ends
and preserve the original length and fit of joint. This was
widely heralded as a new and wonderful idea and was backed by men of
means, who built a mill at Joliet, Illinois, which rerolled some rails
in 1897. |
| When I took the
job in 1898, the mill was operating only part time, and yet a mill was
being erected at Kansas City, Kansas, which did some part time work
that year and in 1899. In spite of the fact that neither one of
the two mills had reached anywhere near full operating schedule,
another mill was being erected in New Jersey with dockage for ocean
vessels. To cap the climax, an English company was formed, and
another mill was in process of construction in 1903. I was sent
to each of these four mills when they operated, not one of them
operating one-third of the time. And yet those who furnished the
money for these ventures were convinced that the business would prosper
exceedingly. Reclaiming worn rails was a popular theme in those
days, and some railroads reported better wearing quality in rails
renewed by the McKenna process. |
| But the worn
rails thus treated were of medium carbon Bessemer steel which could
stand hardening by rerolling. The higher carbon Open Hearth rails
began coming to the mills, and results after rerolling were
disastrous. Breakage in process of manufacture and in track
became prohibitive, and business dwindled beyond hope of profit.
It was not difficult to find the reason. Overheating made the
steel brittle, and when properly heated, the rail was distorted by the
strains set up by cooler rolling. Long lengths of intricate
section made proper heating extremely difficult. Many remedies
were tried but with no permanent success. Reclaiming worn rail
joint bars in press and dies provided a respite and did well for a
time, but again the proper heating of high carbon Open Hearth steel was
the stumbling block. Eventually all four McKenna mills went out
of business, simply because high carbon steel rails and rail joint bars
could not stand the heating and rolling punishment to which they were
subjected. |
| Note added by George, III: The rerolling process deformed the steel only a few percent. It is now known that such a few percent (not more and not less) of deformation, followed by the recrystallization that defines the hot rolling process, will result in extreme coarsening of the grains, embrittling the steel. Renewing of the rails (and splice bars) by the methods described here might well have succeeded if my grandfather had had the inspiration to use the first pass through the mill rolls to over deform the rail, followed by redundantly deforming the rail back to the desired shape in the second pass. Sufficient deformation to obtain an smaller grain size and acceptable toughness might then have been obtained. He came close, first with US Patent No. 1,212,964 for rolling rail of unsymmetrical cross section and then with his US Patent No. 1,724,031, which describes the steps of prequenching a just-deformed renewed splice bar before immersing it in hot, viscous oil and then cooling the bar very slowly by placing it in a stack of similarly treated, hot bars. The prequenching stops the undesired recrystallization, and the hot oil minimizes the formation of proeutectoid ferrite, permitting the bulk of the austenite retained thereby to transform nearly isothermally to pearlite during the slow cooling in the stack of hot bars. Modern rails are processed as closely to 100% pearlite as possible, as this gives the best combination of strength and durability. |