EBSD for analysing the twinning microstructure in fine-grained TWIP steels and its influence on work hardening

The hot deformation behaviour of two high-Mn (23-24 wt-%) TWIP steels containing 6 and 8 wt-% Al with the fully austenitic and duplex microstructures, respectively, has been investigated at temperatures of 900-1100°C. In addition, tensile properties were determined over the temperature range from -80 to 100°C. It was observed that in spite of the lower Al content, the austenitic steel possessed the hot deformation resistance about twice as high as that of the duplex steel. Whereas the flow stress curves of the austenitic steel exhibited work hardening followed by slight softening due to dynamic recrystallisation, the duplex steel showed the absence of work hardening and discontinuous yielding under similar conditions. Tensile tests at low temperatures revealed that the austenitic grade had a lower yield strength than that of the duplex grade, but much better ductility, the elongation increasing with decreasing temperature, contrary to that for the duplex steel. This can be attributed to the intense mechanical twinning in the austenitic steel, while in the duplex steel, twinning occurred in the ferrite only and the austenite showed dislocation glide.

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Application to Seismic Dampers in High-Strain-Rate Superplastic Zn-Al Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.3055 ◽

2005 ◽

Vol 475-479 ◽

pp. 3055-3060 ◽

Cited By ~ 5

Author(s):

Atsumichi Kushibe ◽

Koichi Makii ◽

L.F. Chiang ◽

Tsutomu Tanaka ◽

Masahide Kohzu ◽

...

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Work Hardening ◽

High Performance ◽

High Strain ◽

Al Alloys ◽

Al Alloy ◽

Seismic Damper ◽

Fine Grained ◽

Work Hardening Rate

High strain rate superplasticity has been realised at room temperature for the first time with a ultra fine grained Zn-22wt%Al alloy. Zn-Al alloys have some advantages over low-yieldpoint steels in their low work-hardening rate and high ductility. In addition, Zn-Al alloys are environment-conscious because of no harmful metal like Pb. However, when Zn-Al alloys are subjected to plastic deformation, the strain is localised and local fracture can take place because of their low work-hardening property. In this study, a seismic damper was designed with a Ultra fine grained Zn-Al alloy. As a result, an ecological and high performance seismic damper, the so-called “maintenance-free seismic damper”, has been successfully developed.

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Work Hardening in a Fine Grained Austenitic Stainless Steel

THERMEC 2006 - Materials Science Forum ◽

10.4028/0-87849-428-6.4714 ◽

2007 ◽

pp. 4714-4719 ◽

Cited By ~ 1

Author(s):

Chad W. Sinclair ◽

Henry Proudhon ◽

J.D. Mithieux

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Work Hardening ◽

Fine Grained

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Improving Mechanical Properties of 18%Mn TWIP Steels by Cold Rolling and Annealing

Metals ◽

10.3390/met9070776 ◽

2019 ◽

Vol 9 (7) ◽

pp. 776 ◽

Cited By ~ 1

Author(s):

Vladimir Torganchuk ◽

Andrey Belyakov ◽

Rustam Kaibyshev

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Ultimate Tensile Strength ◽

Cold Rolling ◽

Large Strain ◽

Total Elongation ◽

Fine Grained ◽

Average Grain Size ◽

Twip Steels ◽

Cold Rolling And Annealing

The microstructures and mechanical properties of Fe-0.4C-18Mn and Fe-0.6C-18Mn steels subjected to large strain cold rolling followed by annealing were studied. Cold rolling with a total reduction of 86% resulted in substantial strengthening at expense of plasticity. The yield strength and the ultimate tensile strength of above 1400 MPa and 1600 MPa, respectively, were achieved in both steels, whereas total elongation decreased below 30%. Subsequent annealing at temperatures above 600 °C was accompanied with the development of recrystallization leading to fine-grained microstructures with an average grain size of about 1 μm in both steels. The fine-grained steels exhibited remarkable improved mechanical properties with a product of ultimate tensile strength by total elongation in the range of 50 to 70 GPa %. The fine-grained steel with relatively high carbon content of 0.6%C was characterized by ultimate tensile strength well above 1400 MPa that was remarkably higher than that of about 1200 MPa in the steel with 0.4%C.

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