CAJ | 학술논문

通过Gleeble热模拟实验研究了含0.038% Nb (质量分数)的热轧TRIP钢在高温奥氏体区的热加工工艺，借助光学显微镜、扫描电镜和透射电镜分析了组织演变和Nb的析出行为，并利用电感耦合等离子体发射光谱仪定量分析了Nb的固溶/析出程度.在1250℃奥氏体化5 min后添加Nb有70%固溶于奥氏体.在1000℃以上的奥氏体再结晶区变形过程中Nb的析出量仅占总固溶量的3%，不能有效抑制静态再结晶，奥氏体晶粒得到明显细化.在900℃的奥氏体未再结晶区变形前析出Nb量已达到总固溶量的9%，再结晶被抑制而获得拉长状奥氏体.奥氏体未再结晶区变形可促进铁素体转变并细化铁素体晶粒.再结晶奥氏体或形变奥氏体状态下冷却至650℃时分别有占总添加量的48%和40%的Nb仍以固溶态存在.
통과Gleeble열모의실험연구료함0.038% Nb (질량분수)적열알TRIP강재고온오씨체구적열가공공예，차조광학현미경、소묘전경화투사전경분석료조직연변화Nb적석출행위，병이용전감우합등리자체발사광보의정량분석료Nb적고용/석출정도.재1250℃오씨체화5 min후첨가Nb유70%고용우오씨체.재1000℃이상적오씨체재결정구변형과정중Nb적석출량부점총고용량적3%，불능유효억제정태재결정，오씨체정립득도명현세화.재900℃적오씨체미재결정구변형전석출Nb량이체도총고용량적9%，재결정피억제이획득랍장상오씨체.오씨체미재결정구변형가촉진철소체전변병세화철소체정립.재결정오씨체혹형변오씨체상태하냉각지650℃시분별유점총첨가량적48%화40%적Nb잉이고용태존재.
ABSTRACT Hot-rolled TRIP steel with 0.038% Nb was thermomechanically processed on a Gleeble simulation test machine. The microstructural evolution and the precipitation behavior of Nb were analyzed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The amount of Nb in solution/precipitation was quantitatively measured by inductively coupled plas-ma optical emission spectrometry ( ICP-OES) . After austenization at 1250℃ for 5 min, about 70% of added Nb is dissolved into aus-tenite. During hot deformation in the austenitic recrystallized region above 1000℃, only 3% of dissolved Nb precipitates, which is too little to retard static recrystallization of austenite, and then the austenite grain size is markedly refined. Before hot deformation in the austenitic non-recrystallized region at 900℃, the fraction of precipitated Nb is up to 9%, which retards static recrystallization of aus-tenite after hot deformation and results in pancaked austenite grains. Hot deformation in the austenitic non-recrystallized region accel-erates the γ→αtransformation and refines the ferrite grains. After controlled-cooling to 650℃, there are still 48% and 40% of added Nb in solution after thermomechnical processing for recrystallized austenite and deformed austenite, respectively.