Effects of cooling rates on microstructures and mechanical properties of Nb-Ti microalloyed steel
(0) 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 ℃.
Nb-Ti microalloyed steel cooling rate microstructure hot ductility
Zhao Sua Wu Yujuan He Meifeng Zhang Li
School of Mechanical Engineering, Shanghhai Dianji University, 690 Jiangchuan Road, Shanghai 200240, National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800D School of Material Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road,Shangh Research Institute, Baoshan Iron& Steel Co.Ltd., 890 Fujin Road, Shanghai 201900, PR China
国际会议
上海
英文
207-207
2012-10-19（万方平台首次上网日期，不代表论文的发表时间）