CAJ | 학술논문

用MMS-300型热力模拟试验机研究了含铌微合金低碳钢奥氏体连续冷却过程的相变规律,用热膨胀法结合金相法建立了实验钢变形和未变形奥氏体的连续冷却转变曲线(CCT),研究了加速冷却和热变形对组织转变的影响.结果表明:同静态CCT曲线相比,实验钢的动态CCT曲线整体向左上方移动,随冷却速度的增大,γ→α相变开始温度逐渐降低;高温变形促进铁素体和珠光体相变,同时抑制了贝氏体相变,扩大了铁素体转变区;奥氏体变形对贝氏体转变有双重作用:当冷速较低时,变形抑制贝氏体相变;冷速较高时变形促进贝氏体相变.
용MMS-300형열력모의시험궤연구료함니미합금저탄강오씨체련속냉각과정적상변규률,용열팽창법결합금상법건립료실험강변형화미변형오씨체적련속냉각전변곡선(CCT),연구료가속냉각화열변형대조직전변적영향.결과표명:동정태CCT곡선상비,실험강적동태CCT곡선정체향좌상방이동,수냉각속도적증대,γ→α상변개시온도축점강저;고온변형촉진철소체화주광체상변,동시억제료패씨체상변,확대료철소체전변구;오씨체변형대패씨체전변유쌍중작용:당랭속교저시,변형억제패씨체상변;랭속교고시변형촉진패씨체상변.
The transformation behavior of Nb-bearing micro-alloyed low carbon steel during continuous cooling was investigated by means of MMS-300 thermomechanical simulator. The CCT curves under deformed and un-deformed conditions were obtained by thermal dilation and metallography. The effects of hot deformation and accelerated cooling on microstructure transformation were studied. The experimental results show that the dynamic CCT diagrams shift to the left and upper compared with the static ones, and the onset temperature of γ→α transformation is gradually lower with the increase of cooling rate. The transformation of ferrite and pearlite is accelerated and the transformation of bainite is retarded by high temperature deformation, so the transformation range of ferrite increases; the deformation of austenite has double effects on the transformation of bainite: the deformation inhibits bainite transformation at low cooling rate and promotes bainite transformation at high cooling rate.