英语翻译1.IntroductionThe precipitation and growth of aluminum n

英语翻译
1.Introduction
The precipitation and growth of aluminum nitride in lowcarbon
Al-killed steel is one of the fundamental metallurgical
processes that affect the final microstructure and properties
(Ref 1).The microstructure of steel evolves during hot rolling
and cooling process.The various important factors,which
affect the microstructure of the steel,are dissolution of AlN
during heating and soaking,strain-induced precipitation of AlN
during hot rolling,interpass recrystallization,austenite grain
coarsening,finish rolling temperature (FRT),and cooling of the
strip.The evolution of grain size has been shown (Ref 2) to be
different in low-carbon steel than that of other steels.Thin slab
casting and rolling (TSCR) of low-carbon steel has some
distinguished characteristics,such as finer microstructure.
Much faster cooling rate and rapid solidification (Ref 3) in
association with liquid core reduction result in finer grains in
thin slabs as compared to conventional thick slabs.This initial
austenite grain size of slab plays an important role for
controlling the final microstructure of the strip.During casting,
some aluminum nitrides also precipitate in thin slabs before
entry into the tunnel furnace and may not dissolve during
heating and soaking (Ref 4) at 1150 2C for about 22 min.These
fine precipitates restrain the growth of recrystallized austenite
grains,which significantly affect the final microstructure.
Further,during hot rolling process some amount of fine AlN
precipitates at different stages because of strain and decrease in
temperature.These precipitates inhibit austenite grain growth
by pinning grain boundaries leading to refining of austenite and
hence ferrite grains.The equilibrium solubility of AlN in
austenite at different temperatures and its isothermal precipitation
have been studied by different investigators (Ref 5-8).
Low-carbon Al-killed hot rolled steels are extensively used
for cold forming,cold rolling,enameling,and galvanizing
applications.These steels are almost similar in chemistry but
have significant variations in mechanical and microstructural
properties.Nitrogen in solid solution strongly influences the
mechanical and formability properties of the steel.The
detrimental effects of nitrogen in steel are increased YS,lower
ductility and toughness,higher impact transition temperature
(ITT),and susceptibility to strain aging.The important
properties of hot band for cold forming application are lower
YS,lower yield to ultimate tensile strength (UTS) ratio,higher
elongation and resistant to strain aging