微合金贝氏体钢动态再结晶实验研究.doc

精品文档 PAGE 可编辑 微合金贝氏体钢动态再结晶实验研究 摘要 本文叙述了贝氏体钢的最新发展、应用状况及发展前景，并在Gleeble—1500D热模拟实验机上测定微合金贝氏体钢在不同变形量（55％，70％，85％）、不同变形温度（850℃，900℃，950℃，1050℃，1150℃）及不同变形速率（0.01s-1，0.1s-1，1s-1，10s-1）下的应力—应变曲线，研究其动态再结晶行为，得到影响规律，观察变形后的组织；计算贝氏体钢的热变形激活能；并根据合金元素作用对比贝氏体钢(KB250)与珠光体钢(U75V)发生动态再结晶的程度。此外，根据包钢轨梁厂的现场工艺，进行了六道次模拟实验，对比了不同变形温度，间隙时间和压下量的影响，确定了优化工艺，为现场生产提供实验依据。 结果表明：在变形量为70％，变形速率为0.01s-1的条件下，产生动态再结晶现象的临界温度在850℃左右。当温度为850℃，速率在1s-1以上时未发生动态再结晶现象，速率在0.1s-1以下时发生部分动态再结晶现象；当温度为950℃、1050℃、1150℃时，速率在1s-1以上时均未发生动态再结晶现象，速率在0.1s-1以下时发生明显的动态再结晶现象；分别观察变形量为55％、70％、85％的再结晶曲线，得到随着变形量的增大，动态再结晶愈来愈明显。 利用Arrhenius双曲正弦函数计算贝氏体钢的热变形激活能Q为423.32kJ/mol。比较贝氏体钢（KB250）与珠光体钢（U75V）的真应力—真应变曲线看出，贝氏体钢较珠光体钢更延迟发生动态再结晶现象，这是由于贝氏体钢中含有的大量Mn、Cr、Ni等合金元素延迟动态再结晶。 多道次轧制模拟试验确定最终的优化工艺是：六道次变形温度为1000℃-990℃-980℃-850℃-830℃-810℃，间隔时间为3s-3s-10s-4s-4s，最后一道次将变形量由原来的21％增加到35％。 关键字：贝氏体钢；热模拟；动态再结晶；激活能；优化工艺 Microalloyed bainitic steel experimental study of dynamic recrystallization Abstract This paper describes the latest development of bainitic steel,application status and prospects,and in the Gleeble-1500D thermal simulation testing machine measured microalloyed bainitic steel at different deformation (55%,70%,85%),the different deformation temperature (850℃,900℃,950℃,1050℃,1150℃) and different strain rate (0.01s-1,0.1s-1,1s-1,10s-1) stress - strain curve of the dynamic recrystallization, we obtained the law, observe the deformation of the organization; calculation of bainitic steel hot deformation activation energy; and in accordance with the role of alloying elements compared with the pearlitic steel(KB250) and Bainite Steel(U75V) the extent of dynamic recrystallization. In addition, according to the package plant on-site rail beam technology, simulation experiments carried out six times, compared to a different deformation temperature, the amount of space and time pressure influence the optimization process to determine, to provide experimental basis for on-site production. The results showed that: 70% in the deformation strain rate of 0