Improvement of high speed plastic deformation behavior of ultrafine grained high Mn steel

高速与低速（准静态速率）下的强度差（DSHQ）在工业应用中期望变得更大。本研究的目的是获得一个合适的DSHQ高锰TdR（孪生诱导塑性）钢。制备了具有不同微观结构的样品，然后通过室温拉伸试验在高达10^3/sec的应变速率下测量这些塑性行为。当试样完全再结晶时，随着平均晶粒尺寸的减小，强度增大，但DSHQ减小;而细晶粒和片层位错的混合结构可以成功地获得较高的强度和较大的DSHQ。显微组织观察表明，DSHQ的提高与孪晶变形的出现相对应。

Difference between the strength at high speed and that at low speed (quasi-static rate) (DSHQ) is desired to become larger value for industrial applications. The aim of this study was to obtain an appropriate DSHQ in high Mn TWIP (Twinning induced plasticity) steel. The samples with different microstructures were fabricated and then those plastic behaviors were measured by room temperature tensile test at a strain rate up to 10^3/sec. When the sample was fully recrystallized, the strength becomes larger but the DSHQ decreases with decreasing of the mean grain size ; whereas the higher strength with larger DSHQ can be achieved successfully by means of the mixture of fine grains and lamellar dislocation structure. The microstructural observations clarified that the improvement of DSHQ is corresponded with the appearance of twinning deformation.