RESEARCH PAPER |
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Effects of Electric Pulse on the Solidification Structure and Properties of Cast High Toughness Ductile Iron |
DONG Jie1,2, YUAN Shouqian1,2, YANG Shuangping1,2, SUN Yongtao3, GAO Hailong1, CHEN Chunjiang4
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1 School of Metallurgical Engineering, Xi’an University of Architecture & Technology; 2 Research Centre of Metal lurgical Engineering & Technology of Shaanxi Province, Xi’an 710055; 3 Shanxi Hua-xiang Group Co., Ltd., Linfen 041600; 4 MCC-SFRE Heavy Industry Equipment Co., LTD, Fuping 711700 |
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Abstract Cast high toughness ductile iron QT400-18 was treated by the electrical pulse. The electric pulse parameters were voltage 2 600 V, frequency 0.88 Hz, capacitance 200 μF and the processing time 15 min. The results showed that the undercooling degrees of cast iron specimen treated by the electrical pulse increased 12 K comparing with the untreated one, for improving the graphite nucleation and the dynamic conditions of growth. Then the size of spherical graphite decreased and the number of nodular graphite increased. After the electric pulse treatment, the nodularity was increased from an average of 80% to 91% and the spherical graphite number was increased from 172 /mm2 to 209 /mm2. The graphite was not easy to abnormal growth and the roundness was improved. At the same time,the solidification structure of nodular cast iron has been changed,with the ferrite number increased,83%,compared to untreated specimen increasing 26.6%.The grain size of ferrite was less than that of untreated and the number and interlayer spacing of pearlite in the matrix decreased. The tensile strain increased by 4.89% and the impact work Akv at -233 K increased by 3.56 J.
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Published: 25 October 2017
Online: 2018-05-05
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