Acta Metallurgica Sinica (English Letters) ›› 2019, Vol. 32 ›› Issue (6): 746-754.DOI: 10.1007/s40195-018-0828-z

Special Issue: 2019年钢铁材料专辑

• Orginal Article • Previous Articles     Next Articles

Grain Size-Dependent Mechanical Properties of a High-Manganese Austenitic Steel

Wang Xiao-Jiang1,2(), Sun Xin-Jun2(), Song Cheng1, Chen Huan2, Tong Shuai2, Han Wei2, Pan Feng1   

  1. 1 School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
    2 Department of Structural Steels, Central Iron and Steel Research Institute, Beijing 100081, China
  • Received:2018-07-29 Revised:2018-08-22 Online:2019-06-10 Published:2019-06-17

Abstract:

The effect of grain size on the mechanical properties of a high-manganese (Mn) austenitic steel was investigated via electron-backscattered diffraction, transmission electron microscope, X-ray diffraction, and tensile and impact tests at 25 °C and - 196 °C. The Hall-Petch strengthening coefficients for the yield strength of the high-Mn austenitic steels were 7.08 MPa mm0.5 at 25 °C, which increased to 14 MPa mm0.5 at - 196 °C. The effect that the grain boundary strengthening had on improving the yield strength at - 196 °C was better than that at 25 °C. The impact absorbed energies and the tensile elongations were enhanced with the increased grain size at 25 °C, while they remained nearly unchanged at - 196 °C. The unchanged impact absorbed energies and the tensile elongations were primarily attributed to the emergence of the micro-twin at - 196 °C, which promoted the cleavage fracture in the steels with large-sized grains. Refining the grain size could improve the strength of the high-Mn austenitic steels without impairing their ductility and toughness at low temperature.

Key words: High-Mn, steel, Grain, size, Low-temperature, toughness, Hall-Petch, Micro-twin