【摘要】 研究了N元素对C-Mn钢在740⁹00℃的热加工性能的影响,并分析讨论其影响机理,以及N、Al元素的作用。为模拟钢管热变形时的状态,将试样直接加热到740⁹00℃,采用1×10^-3 s^-1应变速率进行拉伸,并用断面收缩率评价热塑性。试验结果表明:随着N含量的增加,C-Mn钢在740⁹00℃的热塑性降低,峰值应力升高;N会促使Al N沿奥氏体晶界析出,促进沿晶断裂;N会抑制动态再结晶,这可能是氮加宽热塑性低谷区的原因;AlN的析出由Al含量和N含量的乘积决定,降低Al含量也有助于改善钢的热塑性。更多还原

【Abstract】 Investigated is the influence by Element N on the hot workability of the C-Mn steel within the temperature range as 740~900 ℃. Also discussed are the mechanism of the influence,and the effects by N and Al. To simulate the thermo-mechanical conditions, tensile tests are carried out to the specimens as directly heated to a temperatures ranging from 740 to 900 ℃ with an initial strain rate of 1×10-3s-1. After each test,the reduction of cross section area of the specimen is used to measure the hot ductility. The test results indicate that when nitrogen content is rising,the hot ductility of the C-Mn steel is going down within the temperature range as 740~900 ℃,whereas the stress peak going up. It is also identified that nitrogen causes fine Al N precipitated along the austenite grain boundaries, promoting low ductility intergranular failure, and that nitrogen also retards dynamic re-crystallization,which probably is why nitrogen widens the hot ductility trough area. Moreover the Al N precipitation is determined by the product of N content and Al content,and therefore the hot ductility of the said steel can be improved by means of decreasing Al content within the foresaid temperature range.更多还原