中文摘要：

研究了一种新型Nb-V复合微合金非调质钢在不同加热温度和保温时间下的奥氏体晶粒长大规律,并与35MnVN非调质钢进行了对比。讨论了微合金元素Nb、V的存在形式及作用机理,并提出了该钢种较合理的加热工艺。试验结果表明,Nb-V复合微合金非调质钢在1280℃和1140℃下,其奥氏体中的Nb、V主要以NbC、VN相形式析出。利用ASTM晶粒度级别等于5.0的临界判据定义Nb-V复合非调质钢奥氏体晶粒长大温度为1150℃,比35MnVN非调质钢粗化温度提高了50℃,表明该钢种在高温加热时具有较好的抗晶粒长大能力,故其开锻前加热温度应控制在1150～1200℃,保温时间30～60min为宜。

英文摘要：

The austenite grain growth behavior under different heating temperatures and holding time was studied for new type Nb-V alloying non-quenched and tempered steel,and comparison was made with 35MnVN non-quenched and tempered steel. With discussing the presence state and effect mechanism of micro-alloying element Nb, V, a reasonable heating process was brought up. The test results show that Nb and V elements in austenite precipitate in form of NbC and VN phases in the Nb-V steel at 1280 ℃ and 1140 ℃. The austenite grain growth temperature of the Nb-V alloying steel is practically defined as about 1150 ℃ according to ASTM grain size grade G =5.0,which is 50 ℃ higher than that of 35MnVN steel. The results show that the Nb-V non-quenched and tempered steel has good anti-coarsening ability at elevated temperature. Consequently, the reasonable heating temperature is 1150 ℃ - 1200 ℃, and holding time is 30 -60 min before forging.