New-York tribune., 1868-02-20
BREAKING OF RAILS AND AxLEs


BREAKING OF RAILS AND AxLEs
70 ns Editor Of TA< TTtbrne
SIR:I do not know who first promulgated
tho idea that iron becomes crysalized by long use
continued strain, and repeated conclusions. We
hear great many talk learnedly OF the nber
OF iron, yet 1 have met with very few VINO coulu
tell me what makes iron 1brous, and nave aSkeh
the question hundreds OF times Manufacturers and
dealers In iron nick bar side and bend over
carefully SO It will show spllnters piece OF oak or
hickory would show II bet IN the same MANNER no
customer looks at H. and Is highly pleased; hut II ne
tneS that the more foreign aOldsthere
n iuterspersed through the iron the more nDros u WI"
he he would not be 30 well pleased. The lHmin@, or
snters IN merchant iron owing 10 the intervening of
materials hich prevents the iron from uniting or weld
g m e. h ~ r bpcause there IL not enough of the neces
sary foreign substances mi xed through IT, And VINO does
not know that bar of mild steel is togier and stronger
than any brcas ronf Now in regard to iron becoming
crysalized by conclusion. &c this ideawhleh hope
10 show is faaeous-was based the fact that where
bars shafts &C. have accidentally broken they show
variety Of crystals at the place OF fracture; and was
supposed that change In the form and size OF crystals
had been produced by conclusion and strain whereas
the fact change Of the kind had taken place-tbe
same variat having existed at the time the bar was
made. / can go into any rolling-mll or forge in the
country aia show you the same thing N bars not
sE o @s s"S ySH nS plenty ES iO Of Old steel
which have been subjected to millions Of blows from
heavy sedg; break many OF them as you please ana
you viii fnl uniform crystal, and no dninuton OF
strength When railroad superintendents order their
rails 10 be mlde with "cod short tops or heads and
red short" webs and anges, which IL frequently done
they 10 two classes or crystals ana
SO long ms trs shafts axles 30. made by welding
pile or gt OF bars together this state Of things VIII ex
s and the consequence is that after the bars have been
subecfd 70 variable temperatures for length OF time
the sr,ngth Of the iron Ia impaired because there Is
difference IN the contraction aud expansion Of the differ
eut the which, In the Of time destroys
the cohesion Of the molecules which the strength OF
iron aid steel depends The crystal becomes disinte
graet the finer grained crystals expand more than the
cOarst do. Iron cables which have stood the Govern
iest and then been allowed to lie cthOd being
used br many years. found to be weak and unfit for
claimed thaths change s caused by strain
OF Iron rails with steel heads made with the
greatest care capable Of standing the severest tests
weld see and iron TO be perfect after
being In few years give out aud the steel sepaf
aes nom the iron had been merely glued together
IL may be- asked why rails bgeak more frequently 10 ex
reme cold weather than atany other time MANY suppose
1t Il owing the frost In tie iron; that frost effects IRON
and steel chemically This h mistake. The only eneet
fOs cold absence OF heat has on iron Is ~ make
contract aud when the bar IL composed oarse and hDe
crystazed iron strain is produced and every ex-
penenced worker In iron knows that when IL under
heavy strain II Is very easily broken by blow. Many
.uppose that steel Is brittle than iron In cold
weather This is another mistake Steel Ia iron nearly
free from mealods 10 TO rs per cent 40 TO 75OO per cenp
carbon chemically combined and II contracts and ex
pands uniformly aud IN proportion TO the character OF
crystal was Informed by Russian railroad officer that
In hs country they formerly broke from Il 10 IA best Low
Moore tyrcs where they break one steel tyre IL not
this conclus METALLURGIsr