Transformation-induced High Uniform Elongation in a Nanostructured Alloy
Substantial efforts have been placed on developing bulk nanostructured metals as they are expected to exhibit both high strength and good ductility according to the extrapolation of the grain size dependence of mechanical properties of conventional materials. While the promised gain in strength has indeed been realized in nanostructured metals, the elongation to failure is disappointedly less than a few percent, and the uniform elongation, i.e. the plastic strain before localized deformation starts in the engineering stress-strain curve, is even smaller. Here we present observation of high strength and good uniform ductility in a bulk nanostructured austenitic alloy. The grain size was refined to about 150 nm by repetitive phase transitions through conventional rolling and annealing process. The bulk nanostructured alloy provides high yield strength of 860 MPa, five times higher than that of coarse-grained one, and high tensile strength of 1140 MPa. The uniform elongation is also above 30％ mainly due to the additional strain-hardening caused by strain-induced martensitic transformation during tensile tests. The present results probably pave the way to develop ductile bulk nanostructured alloys by thermomechanical processes.
Nanocrystalline Metastable austenite Grain refinement Uniform elongation
Yunqing Ma Young-Kook Lee Cuiping Wang Xingjun Liu
Department of Materials & Engineering, Xiamen University, Xiamen 361005, P. R China Department of Metallurgical Engineering, Yonsei University, Seoul 120-749, South Korea
国际会议
厦门
英文
624-627
2006-11-08（万方平台首次上网日期，不代表论文的发表时间）