Abstract: A ultra low carbon high strength steel heavy plate (60∼80mm thick) was produced with
TMCP at Xiangtan Steel. The steel has a good combination of high strength (σb∼600MPa) and impact
toughness (∼300J). The microstructural features were analyzed by optical microscopy and scanning
electron microscopy (SEM). Results showed that microstructures consisted of a large amount of
acicular ferrite and a small amount of polygonal ferrite. A very few amount of retained austenite was
also observed in the microstructures. The formation of fine acicular ferrite resulted in the high
strength of the steel plate. The good impact toughness of the steel plate is mainly attributed to the
formation of acicular ferrite and a very few amount of retained austenite.
Abstract: The hot workability of modified 9Cr-1Mo, as a grade of heat resistant steels, is inferior to
that of low-alloy steel, so the inner surface crack (ISC) easily occurs in seamless boiler tubes
produced by the Mandrel Mill under improper rolling conditions. With the aid of FEM, the metal flow
status during the rolling process was analyzed in 140mm 8-stand mandrel mill of Bao Steel. Both the
metallographic shape and size of the ISC together with the result from the simulation show that the
ISC of seamless tube forms at the elongation stage of shell. The mechanism of the ISC was discussed.
With its initiation in stand No.1 and No.2 due to poor hot workability of modified 9Cr-1Mo steel, the
ISC develops in subsequent passes. Based upon the mechanism devised was a special roll pass system
which substantially upgraded the yield of qualified products.
Abstract: Dynamic continuous stiffness measurement (CSM) nanoindentation method was applied to
measure nanohardness in low carbon microalloying steel. The matrix hardness for quenched phase
and acicular ferrite calculated through analysis of curves is less fluctuated than the raw results, which
shows that the analysis of the curves is helpful for determining matrix hardness.
Abstract: This study aims to analyze the potential of grain boundary corners (GBCs) as nucleation
sites of bcc precipitates in an fcc matrix. By combined serial sectioning and electron backscatter
diffraction analysis, the crystallography of GBCs and GBC precipitates was analyzed in a Co-Fe
Abstract: An investigation into the compression forming of cylinder using the commercial code
SUPERFORM is developed. The cylinder billet compressed between the upper and lower dies is
meshed by a quadrangle elastic-plastic element. The numerical simulation based on the FEM also
compares with the slab method established by us. In the slab method analysis, the stress distributions
are estimated by considering the coulomb friction between the dies and the cylinder. Throughout this
study, the effects of frictional coefficient, rotating angular speed, reduction and aspect ratio etc upon
the compression force, the effective stress and the effective strain, and velocity field are discussed
systematically. For verifying the validity of two models, comparisons of compression forces based
both modes are carried out to prove the feasibility of both models.
Abstract: Effects of Ti and Nb stabilization on the recrystallization and the pitting potential in
Fe-21%Cr ferritic stainless steels were studied by using optical microscopy, scanning electron
microscopy, transmission electron microscopy and polarization curve measurement. The results show
that both Ti and Nb, either in solution or as precipitates, retard the recrystallization and enhance the
recrystallization temperature. Substitution of Nb for Ti in Fe-21%Cr ferritic stainless steels increases
the recrystallization temperature by 30 to 50°C. Nb and Ti stabilized ferritic steels present higher
pitting potential than Ti stabilized steels.
Abstract: Critical high temperature components of machines and structures are often subjected to
complicated load and temperature histories. The closest laboratory simulation of service loading
conditions involves creep under nonsteady temperatures and stresses. For example, the start up and
shut down cycles can be well simulated by temperature variation by use of intermittent heating tests.
Such approach is illustrated by recent experimental results on advanced high creep strength 9-
12%Cr ferritic-martensitic steels (P91, P92 and E911). A comparison between the creep
characteristics of nonsteady and monotonously creep specimens has revealed no significant
deterioration of the creep strength and fracture resistance of these steels in power-law (dislocation)
Abstract: At the Egyptian Iron and Steel Company, attention is constantly focused on
improving basic steel making practice with the aim of improvement of blowing
regime and the addition of forming slag materials system.
A number of factors considered important in controlling the properties of steel
products and affecting the residual manganese in the basic Oxygen furnace (BOF)
have been investigated by changing some industrial parameters, aiming at optimizing
the residual manganese in BOF. The studied factors were manganese oxide in the
slag, iron oxide in the slag, tapping temperature, Slag basicity, Lance height, blowing
time, and carbon content.
It was found that residual manganese increased from 0.25 to 0.35 % wt, due to the
reduction of both MnO in slag from 22% to 15% and FeO from 21 to18%, also the
increase of tapping temperature from 1650 oC to 1670 oC caused an increase the
residual manganese from 0.27% to 0.35%, and the slag basicity decrease from 4.25 to
3.8 led to an increase in the residual manganese from 0.25 to 0.37%. Also, the change
of the lance height from 1050 mm to 825 mm caused an increase in the residual
manganese from 0.27 % to 0.33 %.
These results are believed to be reflected on the total energy consumption and ferromanganese
additions needed for producing specific grades.
Abstract: Being examined by tensile tests at 820°C with initial strain rates of 2.5×10-4 s-1, 5.0×10-3
s-1and 1.0×10-1 s-1, the hot-rolled spay formed high speed steel (SF-HSS) had superplastic properties.
With έ=2.5×10-4 s-1and 5.0×10-3 s-1, the σ-ε curves indicate that there has occurred dynamic
recrystallization at the later stage of deformation.The tensile elongation decreases monotonously with
strain rate increasing. The strain rate sensitivity m =dlogσ/dlog έ is about 0.23. In the sub-surface of
fractured SF-HSS samples with έ=2.5×10-4 s-1,, most of holes on the subsurface are observed to
distribute near the carbides and arranged along the tensile axis direction. The interface between coarse
carbides and matrix is very weak sites where the holes are easy to nucleate and connect to cracks
during deformation. In the necked region, fine carbide particles on the grain boundary have pinned the
slip of dislocations and formed dislocation wall inside the grain. Dynamic recrystallization and some
climb of dislocations has occurred. The superplastic deformation mechanism with έ=2.5×10-4 s-1 was
dislocation creep mechanism controlled by dynamic recrystallization. During deformation, the role of
some carbide in the materials was to retard the grain growth and keep SF-HSS having fine equiaxed
grain size and remain stable.
Abstract: Creep tests and microstructural observations in several high Cr ferritic steels bearing V
and Nb were carried out in order to investigate effects of addition of V and Nb on , which is a
coefficient of method. Creep strength was improved with increasing the V content and was slightly
lowered by increasing the Nb content. in all the steels bearing V or Nb was lager than that in
fundamental steel. The dependence of on the amount of additions was different between V and Nb.
In steels bearing V, became larger with increasing V content. In steels bearing Nb, became
smaller. These results revealed that corresponds to the creep strength, indicating that the value of
can be estimated using the strengthening effects of the additive element.