J Mater Sci Technol ›› 1992, Vol. 8 ›› Issue (5): 369-375.

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Low Ductility at Elevated Temperatures of the Cryogenic and Non-magnetic Steel Fe-23Mn-4Al-SCr-0.3C

TIAN Xing ZHANG Yansheng Dalian Railway Institute,Dalian,116022,China   

  • Received:1992-09-28 Revised:1992-09-28 Online:1992-09-28 Published:2009-10-10

Abstract: The origin of low ductility at elevated tempera- ture in the cryogenic and non-magnetic steel Fe-23Mn-4Al-5Cr-0.3C was investigated by means of impact test at elevated temperatures,opti- cal microscope,SEM and TEM.The experimental results indicate that the impact toughness lowers with increasing testing temperature,and exhibits a low trough of ductility from 865℃ to 1050℃ and a peak value at 1150℃.The intergranular fracture occurs in the temperature region of low ductility and the transgranular ductile rupture below this re- gion principally.There is a process of precipitating, gathering,growing,and dissolution of carbide (FeMnCr)_(23)C_6 and AlN between 500℃ and 1000℃.The coalescence of microvoids caused by the process at grain boundaries results in the intergranular fracture and the low ductility at ele- vated temperatures.

Key words: ductility, precipitation, grain boundary, intergranular fracture, microvoid