| The effects of the alloy content of Si, Ni and V on impact toughness, in 0.6C-(1.0-2.5)Si-(0.7-1.8)Ni-(0.1-0.2)V steels, were investigated by performing Charpy impact tests, the measurement of volume fraction of retained austenite and microstructural examination with transmission electron microscopy. The results showed that the increase of Si content shifted the embrittlement temperatures to higher temperature, due to Si effect of retarding the formation and growth of cementite at boundaries. Additionally, it was found that the temperature of the peak in Charpy impact curves coincided with the onset of the decomposition of retained austenite. The temperatures of the conversion of ε-carbide to cementite and of the onset of TME were not changed by the Ni addition in the present steels. However, the decomposition of retained austenite was delayed and the toughness was increased over all the tempering temperatures. The contribution of the V addition in the present steels was limited only to the increase impact toughness. |
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