不同工艺下Nb-Ti微合金钢组织演变和析出行为

利用Gleeble 3800热模拟实验机、透射电镜和纳米压痕仪器等研究了终冷温度和保温时间对Nb-Ti微合金钢组织、析出行为的影响规律.结果表明:随终冷温度的升高,铁素体晶粒尺寸增大,珠光体增多,贝氏体逐渐减少,维氏显微硬度随终冷温度先升高后降低,当终冷温度为640℃时,实验钢的维氏显微硬度最大;当终冷温度为640℃时,试样中存在排列规则的相间析出和弥散分布的随机析出两种析出形式.当保温时间为0s时,析出物以相间析出和弥散析出为主;当保温时间为100s时,析出物以弥散析出为主.随保温时间增加,实验钢的纳米硬度降低了140MPa.

Microstructure Evolution and Precipitation Behavior of Nb-Ti Microalloyed Steel Under Different Processing

The effects of different finish cooling temperature and holding time on microstructure,precipitation behavior of Nb-Ti microalloyed steel were investigated by using Gleeble 3800 thermal mechanical simulator,transmission electron microscope(TEM) and nanoindentation instruments.The results showed that with the increase of the finish cooling temperature,the size of ferrite and the fraction of pearlite increase,and the fraction of bainite reduces,the Vickers microhardness increases first then decreases and reaches the maximum when the finish cooling temperature is 640 ℃.Rows of interphase precipitate and randomly dispersed precipitates can be found in ferrite matrix when the holding time is 0 s,and when the holding time is 100 s,the main precipitation is randomly dispersed precipitates.With the increase of the holding time,the nanoindentation is reduced 140 MPa.