二冷区温度波动下含Nb-Ti微合金钢热塑性行为研究  

Research on Hot Ductility Behavior of Nb-Ti Microalloyed Steel with Temperature Fluctuation in Secondary Cooling Zone

作　　者：唐国章 曾亚南 李俊国 

机构地区：[1]华北理工大学冶金与能源学院,河北唐山063009

出　　处：《热加工工艺》2016年第22期47-51,共5页Hot Working Technology

基　　金：河北省自然科学基金(E2013209234)

摘　　要：基于国内某厂二冷区温度波动的实际生产工艺,利用Gleeble-3500热模拟试验机对温度波动下的Nb-Ti微合金钢进行拉伸测试。采用扫描电镜、光学显微镜对试样断口形貌及组织进行观察。结果表明:随温度波动幅度(ΔT)增大,铸坯脆性区右移。ΔT每升高25K,脆性区温度提高50 K左右。低温时,铸坯塑性几乎不随温度波动幅度变化而变化。随拉伸温度降低,试样断口由穿晶断裂开始向沿晶断裂转变。基体及韧窝底部存在夹杂物或第二相粒子,为空穴形核提供条件,成为恶化铸坯塑性的重要因素。随温度下降,铁素体逐渐形成。在相同测试温度下,温度波动越大对铁素体含量的影响更加明显。铁素体体积分数为36%时,该钢的热塑性达到最低值。Based on practical parameters of temperature oscillation in secondary cooling zone, the tensile test of Nb-Ti microalloyed steel was carried out by Gleeble-3500 under temperature fluctuation. The fracture morphology and microstructur~ of the steel were investigated by SEM and optical microscopy. The results indicate that the brittle zone of casting blank moves to the fight side with the increase of temperature fluctuation .The brittleness zone temperature improves about 50 K with the amplitude of temperature variation （AT） elevated by 25 K. The hot ductility changes unobviously with the amplitude of temperature fluctuation at low temperature. With the tensile temperature decreasing, the sample fracture transforms from transgranular fracture to intergranular fracture. The inclusions or precipitations which can provide conditions for void nucleation, appears in the matrix and dimple. The hot ductility is deteriorated by inclusions or precipitations. The ferrite forms with the temperature decreasing. The temperature fluctuation has obvious impact on the ferrite content at the same testing temperature. When the ferrite volume fraction is 36%, the hot ductility ofthe steel reaches the minimum value.

关 键 词：微合金钢 温度波动 热塑性 析出物 铁素体 

分 类 号：TG113.25[金属学及工艺—物理冶金]