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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。
A new type of Nb-V microalloying non-quenched and tempered steel under different heating temperature and holding time austenite grain growth rule, and 35MnVN non-quenched and tempered steel were compared. The existence forms and mechanism of microelements Nb, V are discussed, and a more reasonable heating process is proposed. The experimental results show that Nb and V in austenite of Nb-V composite micro-alloyed non-quenched and tempered steels mainly precipitate in NbC and VN phases at 1280 ℃ and 1140 ℃. Using the critical criterion of ASTM grain size grade equal to 5.0, the grain growth temperature of austenite in Nb-V composite non-quenched and tempered steel is defined as 1150 ℃, which is 50 ℃ higher than the roughening temperature of 35MnVN non-quenched and tempered steel, When heated at high temperature, it has good resistance to grain growth, so the heating temperature before open forging should be controlled at 1150 ~ 1200 ℃, holding time is 30 ~ 60min is appropriate.