【摘 要】
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The mechanical properties and microstructure of as-cast Nb-Ti microalloyed steel at different temperatures and cooling rates were investigated.The Ⅲ brittl
【出 处】
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2012 Postdoctoral Symposium of China on Materials Science &a
论文部分内容阅读
The mechanical properties and microstructure of as-cast Nb-Ti microalloyed steel at different temperatures and cooling rates were investigated.The Ⅲ brittle zone (700℃ ~900℃) is revealed.The reduce of the hot ductility is due to the film-like proeutectoid ferrite or the Nb(C,N) precipitates along the austenitic grain boundaries.In the temperature range of 850℃ ~ 1000℃, with the increase of the cooling rate, the hot ductility decreases.However, in the range of 650℃ ~ 850℃, the appearance of large volume fractions of ferrite on austenite grain boundaries minimizes the effect of cooling rate on hot ductility.When the cooling rate is 10℃/s, austenite transforms more quickly to ferrite and at a lower temperature a larger amount of ferrite nucleates and precipitates in the grain, which leads to a sharper improvement in hot ductility at 650℃.
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