CAJ | 학술논문

采用 Gleeble-3500型热模拟试验机，测定一种高 Nb 微合金钢的变形前后及变形弛豫后的 CCT 曲线，并测定了奥氏体化、变形弛豫前后钢中固溶 Nb 的含量，分析了变形及弛豫对 CCT 曲线及组织的影响，结果表明：变形促进相变，使 CCT 曲线向左上方移动，并细化室温组织。变形后弛豫过程中，由于回复、再结晶的发生，降低了奥氏体的形变储能，降低了变形对组织的细化作用，使室温组织粗化。此外，Nb 的析出降低了奥氏体中固溶 Nb、C 的含量，从而减弱了对相变的抑制作用，使相变温度升高。
채용 Gleeble-3500형열모의시험궤，측정일충고 Nb 미합금강적변형전후급변형이예후적 CCT 곡선，병측정료오씨체화、변형이예전후강중고용 Nb 적함량，분석료변형급이예대 CCT 곡선급조직적영향，결과표명：변형촉진상변，사 CCT 곡선향좌상방이동，병세화실온조직。변형후이예과정중，유우회복、재결정적발생，강저료오씨체적형변저능，강저료변형대조직적세화작용，사실온조직조화。차외，Nb 적석출강저료오씨체중고용 Nb、C 적함량，종이감약료대상변적억제작용，사상변온도승고。
@@@@The effects of hot deformation and relaxation process on the continue cooling transformation (CCT) diagrams of a high-Nb microalloyed steel are determined by the means of the thermal simulation on a Gleeble-3500 thermal mechanical simula-tor. The results show that the hot deformation shifts the CCT curves to up and left, promoting the phase transformation with the refinement of the microstructure. The recovery and recrystallization involved in the relaxation process after hot deformation de-creases the deformation energy and, consequently, the refinement effect of the deformaton decreases, leading to coarse micro-structures at room temperature. Moreover, the amount of dissovled Nb and C in austenite decreases due to the precipitation of Nb, which weakens the restraining effect of Nb and C on phase transforntion and results the increase of the phase transformation tem-perature.