含Nb-Ti微合金钢第三脆性区铸坯缺陷  

Defection in Low Brittle Temperature Zone of Nb-Ti Micro-Alloyed Steel Slab

作　　者：徐蕊[1] 孙彦辉[1] 曾亚南[1] 蔡开科[1] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083

出　　处：《钢铁研究学报》2014年第11期45-50,共6页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(51274032)

摘　　要：采用金相显微镜、复型萃取、SEM、TEM对析出物的形貌、尺寸、数量进行统计分析,并利用Gleeble-1500热模拟试验机,系统研究了含Nb-Ti微合金钢第三脆性区的热塑性。结果表明：温度在950-700℃范围内时,断面收缩率最小为25.7%。析出物以TiN、Nb（CN）为主,950℃时粒子尺寸在50nm左右。随着温度的降低,粒子数量密度由51个/μm2增加到580个/μm2,尺寸随之减小。975℃的抗拉强度及临界应力分别为58.3、61.0 MPa。975℃以上,临界应力小于抗拉强度,不易发生沿晶断裂。975℃以下时,晶粒变形临界应力大于抗拉强度,产生沿晶断裂。The morphologies,sizes and quantities of the precipitations in Nb-Ti micro-alloyed steel slab were studied systematically by using metallographic microscope,carbon extraction replicas,SEM and TEM.The hot ductility in low brittle temperature zone of the steel was also tested by Geelble-1500.The results show that when temperature is in the range from 950 to 700 ℃,the lowest value of RA is 25.7%.The precipitations are mainly TiN and Nb（CN）,and their sizes are about 50 nm at 950 ℃.With temperature decreasing,the quantity of the particles increases from 51 to 580/μm2 while the size decreases.At 975 ℃,the tensile strength and critical stress are58.3and 61.0 MPa respectively.Over 975 ℃,the critical stress is smaller than the tensile strength,it is difficult to produce inter-granular failure.Under 975 ℃,it is apt to produce inter-granular failure when the critical stress for grain deformation is larger than the tensile strength.

关 键 词：微合金钢 第三脆性区 析出物 临界应力 

分 类 号：TG245[金属学及工艺—铸造]