含铌微合金高强度钢Q345C连铸坯的热塑性  

Hot Ductility of Niobium-Microalloyed High Strength Steel Q345C Slab

作　　者：王生朝[1] 赵刚[1] 鲍思前[1] 石海宁 邓深 张海洲 

机构地区：[1]武汉科技大学材料与冶金学院,湖北武汉430081 [2]柳州钢铁集团公司技术中心,广西柳州545002 [3]广西冶金研究院合金材料研究所,广西南宁530023

出　　处：《钢铁》2012年第1期74-77,共4页Iron and Steel

基　　金：湖南省科学技术厅科技计划资助项目(2011GK3147)

摘　　要：通过Gleeble-2000试验机研究了Q345C钢连铸坯的高温热塑性。利用扫描电镜、金相显微镜、透射电镜观察了第Ⅰ、Ⅲ脆性温度区内拉伸试样断口部位的显微组织及形貌,分析了动态再结晶、相变、析出物等对微合金化钢高温延塑性的影响。结果表明:在1×10-3/s应变速率下,Q345C钢存在两个脆性温度区,即第Ⅰ脆性区(1 200～1 300℃)和第Ⅲ脆性区(600～875℃),无第Ⅱ脆性区出现;最高塑性出现在1 050℃左右,断面收缩率(Z)达到85.8%;在第Ⅲ脆性区,沿奥氏体晶界析出膜状铁素体抗拉能力较低,晶界处存在夹杂物以及微合金元素的析出物,是钢的热塑性降低的主要原因。Hot ductility of continuous casting Q345C slabs was tested by Gleeble-2000 thermal/strain simulation ma- chine. Using scanning electron microscopy, metalloscopy and transmission electron microscopy, morphology eharac teristics and microstructure of fracture surface of tensile specimen in Brittle temperature zone Ⅰ and Ⅲ were ob served. Influences of dynamic recrystallization, phase change and precipitate on hot ductility of the niobium- micro-alloyed steel were analyzed. The results showed that： at the 1× 10^-3/s strain rate, there are two low ductility zones, namely brittle zone i （1200 1300℃） and brittle zone Ⅲ（600 875 ℃） ,the brittle zone Ⅱ does not exist; the maximum ductility is around 1 050 ℃ and area reduction （Z）reached 85.80/00; in brittle zone Ⅲ , membranous lower tensile strength of ferrite along austenite grain boundaries, and the existence of inclusions and precipitates of micro- alloying elements in the grain boundaries is the main reasons for lower ductility of Q345C steel.

关 键 词：Q345C 断面收缩率 连铸 板坯 热塑性 

分 类 号：TF777[冶金工程—钢铁冶金]