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Two types of austenitic alloy, precipitation hardening austenitic Fe-Ni-Ti alloy and unprecipitation hardening austenitic Fe-Ni alloy, were prepared by high frequency induction melting, and then the effects of cyclic heat treatment and deformation degree on hardness of these reverted austenites have been investigated. (1) The hardness of reverted austenitic Fe-Ni-Ti alloy shows a maximum value at about 700℃ when ausaged for 1 hour at various temperatures, and then decreases as the temperature further increases above 700℃. (2) The Ms temperature of austenitic Fe-Ni-Ti alloy is raised with ausaging treatment. (3) The hardness of reverted austenitic Fe-Ni alloy increases rapidly at 1 cyclic heat treatment, and gradually increases up to 4 cyclic heat treatment. However, at all cycles above 4 cycles the hardness of the reverted austenitic Fe-Ni alloy shows a nearly constant value, independent of cyclic heat treatment number. (4) The hardness of reverted austenitic Fe-Ni-Ti alloy increases rapidly at 1 cyclic heat treatment, and maintains a nearly constant value at all cycles above 1 cycle. (5) When both Fe-Ni and Fe-Ni-Ti alloy subjected to prior deformation are transformed to reverted austenite, the increase in hardness due to reverse transformation is greater in the former alloy than in the latter alloy. At the same deformation degree, the hardness of reverted austenite is slightly higher in case of deformed martensite than deformed austenite. (6) The reverted austenitic Fe-Ni-Ti alloy is mare stable at elevated temperature than the reverted austenitic Fe-Ni alloy.

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There has been great effort and development in producing the high strength steel to attain the best balance of cost reduction and properties. Recently, it has been suggested that a direct quench and temper process after hot rolling be the best method of producing linepipe steel. According to the suggested method, a comparably high carbon equivalent steel (0.16%C-1.33%Mn-0.024%Nb-0.052%V) was quenched and tempered after controlled-rolling. Microstructure was characterized by optical and transmission electron microscopy, and correlated with tensile property. Deformation bands, developed by heavy rolling below the recrystallization temperature, still exist at room temperature and have a bad effect on the property. This structure creates a twin-like diffraction pattern. Direct quench and temper method decreases the strain hardening rate and results in low tensile stress for the comparably high carbon equivalent steel.

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]For various rolling processes, the effects of recrystallized textures of 17% Cr ferritic stainless steel shut on deep-drawability were investigated by using 1) Pole figure analysis, 2) plastic strain ratios derived from tensile tests, 3) earing behavior observed from cup-drawing. For single cold rolling processes, deep-drawability increased with increasing cold reduction. The best combination of high average plastic strain ratio and low planar anisotropy was achieved by 86% cold reduction. For double cold rolling processes having total reduction of 81%, the maximum average plastic strain ratio was obtained with the distribution of reduction, of 50%-62%, and the planar anisotropy decreased with increasing 2nd cold reduction. (111)[211] recrystallized texture was obtained after the (112)[110] component became the main texture of the cold rolled matrix. (011)[100] texture and (001) [110] texture respectively affected γ_(90) and γ_0 with a disproportionality to their small volume fraction. With increasing cold reduction, the (111) [211] texture increased in volume fraction while the (011) [100] texture decreased. The high earing tendency of double cold rolling processed sheets was due to high γ_(90) value by development of (011) [100] texture. The formation of six ears on drawing by sheet reduced 86% is the result of both a strong (111) [211] and a week (112) [110]+(112) [110]±15 ND textures.

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