Investigation Of Nigerian Steels For Cryogenic Application
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Nigeria produces )Steels and has just
entered the league qf Nat!Pfl$ whic!l export
( .. .. . . ' .
~~i4.f?l .9as in t,he t?rm R! li9ui,ti~.d q~tur~l Q'+~
(~f\1~).
L~ h l r;l' • ' ', •
In order to use Nig~rian ~teets. for
cryo~epic temperature applic;ations, th)s \o'Jork
i.s. undert~ken to examin~ the possibility of ~ : . ' . . ' \ . ' ' . .
further developing the steel(?) vyhich ~now
promis~ from cryog~nic temperature tests.
Samples of I'Jig~pan popular steel~ ,
j J ' !' ••; ' I I '
NST44-2, NST-60-2 and NST 60 Mn were
mac,hin~d i~lp ~tan~Cird qh~rpy imp~ct ~esting ··• · - . ... . . '
~w~pim~m . a.~ ~pe~Ifi~'~ by ASTM. These
' samples were neat treated by soaking for 1
l i~: .. -1•{ t '~! ~ ,t.t: o: f ,J~i'\ ! ,{. :·. ~ : ' -
hour at 930.0C and cooled in the air. • ; . ; : . . ' : ·. ~ ' i .
Impacts tests were conducted on these
specimens, of ~~ rolled and normalis~d
conditions at room and cryogenic
t~mper~wres of 0?,~ (273K), -59C ~?(?~~). -
l..i o,,.,\;1 ,,, ·
1
· • · · • · • · · )
1 OoC (263K) and -15oC (258K).
·i' r ::.i j ; ; i ' : ~ ~ .: ::- '! • 1 j , i ;. 'i ~ , ;. ! ) ~ ! ' :
The results show that the steel NST 44-2
· is prom!sing for ~ryogenic ~pplicatiqns. The ductile fracture in NST 44-2 can be attributed -~-- __ ... _.,._~...,. . ... tq t,~fi norm~llslrg ~ffect, where more ferrite
was transformed ~han pE:}arlite from (a + y)
reQion of the heat treatment, which resulted
jn g_r?in _retirem~nt and decrease in ductileqrit.
t!e transition tef'T!peratures. The ductility of
,;. ··' ., ':· • - I ' ~ ·-- ' . . .
th~ ~~mple is due to low carbon content of
the. material.
I~TR ODUCTION
The Nigerian steel company, has been
producing different grades of steels for
· con~truction and manufacturing industries for
engineering component parts.
Nigeria as natural gas producing nation
~ith abund~nt reserves, needs to look
inwards to use her steels to manufacture the
essential component parts for the gas
industry. In order to use Nigerian steel for this
· purpose, it must be noted that the
engineering properties of most structural
steel? ch~n9e ~ubs~antiaUy a~ temperature is
q~c,re~~~·o .to V~JY ·lpw y~!u~. that Is In
cryogen.!c applic(l~ions. Common property
change~ include dhnens.iqn~l contraction,
increas~s in yi~'d ~nd tensjl~ $trengths, ano
. ' \
high energy absorbed -aycompanied by decrease in fractur~ tough~~~s. wit~ · the latt
Keywords
TA Engineering (General). Civil engineering (General), TJ Mechanical engineering and machinery