Abstract: The microstructure of oxide scale formed in the early stage of oxidation of cold-rolled sheets of
17%Cr-Mn-Ni austenitic stainless steel was examined using SEM and TEM. Samples were oxidized at 973
to1373K for 1 to 15min. Nodules were observed on the surfaces of specimens oxidized at 1173K. The nodules
were composed of two layers, which comprised Fe oxides and Cr-rich Fe-Cr-Mn oxides, respectively. The
other scale was composed of two layers of Fe-Cr-Mn oxides with different compositions. Nodules were not
observed on the surfaces of the specimens oxidized at 973 and 1373K. After oxidation at 1373K for 1min, the
scale was composed of three layers. The first layer consisted of Fe-Mn oxides with a spinel structure, the
second consisted mainly of Cr oxides, and the third consisted of Cr-Mn oxides containing a small amount of
Abstract: Susceptibility of hydrogen embrittlement of a super grade AISI 420 tool steel was studied.
Tensile samples were cathodically charged to different hydrogen level. Hydrogen induced mechanical
property degradation was measured by tensile tests at a low strain rate. Fractography of broken
surfaces was observed using SEM. Relationship between hydrogen content and tensile strength and
elongation were studied. Critical hydrogen contents were obtained for different heat treatment states.
It was found that for annealed materials could stand for a 3.5ppm hydrogen for keeping 80% of
original ductility, and the effect of hydrogen on strength was unobvious. However, for material
quenched and tempered at 250°C, only 0.3ppm hydrogen could lead the ductility drop to 80% of
original. The material quenched and tempered at 500°C was more sensitive on hydrogen, less than
1ppm hydrogen could lead the strength drop to 80% of original.
Abstract: Tensile properties of twinning induced plasticity (TWIP) steels (31%Mn-3%Al-3%Si-Fe)
with various mean grain sizes ranging from ultrafine grain size (1.1μm) to conventional one (35.5μm)
at a wide range of strain rates from 10-3sec-1 to 103sec-1 were studied. The ultrafine grained TWIP
steel exhibits a large work hardening and keeps an adequate elongation at any strain rate. The strength
held to the Hall-Petch relationship at each strain rate and the Hall-Petch slopes do not change largely.
Abstract: The precipitation of copper during aging at 650oC within ferrite in high-purity
Fe-1.03wt%Cu steel was examined by transmission electron microscopy, and the influence of
precipitation particles on property of experimental steel was investigated. The microstructure and
the corresponding diffraction patterns of different zone axis were analyzed. Nano-scale copper-rich
clusters with B2-like structure and high density dislocation around precipitate was observed during
either solution treatment or aging. Nano-scale metastable precipitates and high density around them
were found to play the most important role for increasing steel strength.
Abstract: Asymmetric rolling of thin strip has become important due to a significant decrease of
rolling force, which contributes to obtain the extremely thin strip, to reduce the rolling passes, and
to save the energy by a decrease of anneal treatment. In asymmetric rolling of thin strip, edges of
work rolls may contact and deform when no or small work roll bending force is applied. Work roll
edge contact forms a new deformation feature. In this paper, the effects of initial thickness of strip
and friction coefficient on the rolling pressure, roll edge contact length and strip crown during
asymmetric rolling of thin strip with work roll edge contact effect has been discussed, and the
calculated rolling force with work roll edge contact is compared with the measured value.
Abstract: Normally, deformation twinning is a process that occurs at rates approaching the speed of
sound in bulk metals once a critical stress has been reached. However, recently it has been shown
that twins grow at speeds many orders of magnitude lower than the speed of sound during room
temperature creep of titanium alloys. The net result is that this twinning process can contribute to
the low-temperature (less than 0.25*Tm) creep behavior of α, α−β, and β−titanium alloys. For
example, α-Ti alloys with small grain size do not extensively deform by twinning and hence show
little overall creep strain. These recent developments are reviewed in this paper. This work is
funded by the National Science Foundation under Grant Number DMR-0517351.
Abstract: A new surface treatment technology for the aluminum alloys that exhibits not only high corrosion and weather
resistance but also good mirror luster has been developed. By performing electrolytic permeation, the
improved corrosion resistance and weather resistance while maintaining a high mirror luster was achieved for
an aluminum alloy A2014-T6. The high strength aluminum alloys featuring high corrosion and weather
resistance have been available for industrial products. Then the claim number of the products by A2014 T6
aluminum alloy has been reduced sharply to almost zero level in comparison with a past. A few applications
and the development of the processing in industrial scale in A2014 T6 aluminum alloy will be presented.
Abstract: In this paper, the effects of Sb and RE on the solutionized microstructure and
microhardness of Mg-6A1-1Zn-0.7Si magnesium alloy are investigated. The research results indicate
that the solid solution treatment can result to the modification of Chinese script shaped Mg2Si phases
in the microstructure of experimental alloy, and adding small amounts of RE and Sb can strengthen
the modification efficiency. In addition, after the solid solution treatment at 420°C, the
Mg-6A1-1Zn-0.7Si alloy added 0.4%Sb and 0.25%RE exhibits higher microhardness, but the effect
of Sb and RE additions on the changing law between microhardness and solutionized time, is not
Abstract: The effect of RRA treatment with using low retrogression temperatures between 170°C to
190°C on the strength and electrical conductivity (as an indicator of corrosion resistance) of 7B04
aluminum alloy thick plates was investigated. The research results showed that the low-temperature
RRA heat treatment provides a means for improving electrical conductivity of the aluminum alloy
7B04 pre-stretched thick plates without sacrificing the mechanical strength. The RRA temper with
retrogression at 180°C for 60 min improved electrical conductivity remarkably (reached 21.0MS/m),
with only a 3% reduction in strength below T6 temper. Furthermore, TEM observations showed that
the microstructure of RRA treated alloy was a very fine distribution of η′ MgZn2 precipitates in the
aluminum matrix, similar to T6 condition and η MgZn2 precipitates on grain boundaries distributed
similarly to T73 temper.