热芯大压下轧制大方坯内部孔洞压合及表面裂纹分析
Analysis of the surface cracks and void closure of bloom during hot-core heavy reduction rolling
项宁 1李海军 1宁新禹 1李睿昊1
作者信息
- 1. 东北大学轧制技术及连轧自动化国家重点实验室,辽宁 沈阳 110819
- 折叠
摘要
采用热芯大压下工艺可以消除大方坯芯部疏松、缩孔缺陷,然而大方坯应力状态复杂多变,符合大压下变形过程的断裂判据匮乏,制约了热芯大压下工艺的工业化应用.以GCr15大方坯为研究对象,通过设计异形压缩试样获取材料变形时不同的应力状态演化路径,还原了大方坯大压下过程复杂受力情况,建立了适用于热芯大压下轧制工艺的表面裂纹判据;结合大方坯芯部孔洞压合实验有限元模拟,分析了热芯大压下轧制时孔洞形状演变和表面开裂风险.结果表明:得益于热芯大压下大方坯的厚向温度梯度,压下率越大,对于铸坯芯部缺陷的改善效果越明显.当压下率为33.3％时,铸坯芯部孔洞实现完全闭合,且此时铸坯表面实际损伤值低于临界损伤值,不会产生新的表面裂纹缺陷.
Abstract
The hot-core heavy reduction process can eliminate the porosity and shrinkage defects in the core of the bloom,but the stress state of the bloom is complex and variable,and the fracture criterion in accordance with the heavy reduction deformation process is scarce,which restricts the industrial application of the hot-core heavy reduction process.The GCr15 bearing bloom was used as the object of study,the evolution paths of different stress states during material deformation were obtained by desig-ning special-shaped compression specimens to restore the complicated stress states during the heavy reduction of bloom,and then the surface crack criterion was established for the hot-core heavy rolling process.Combined with the numerical simulation,the risk of surface crack and the shape evolution of the void was analyzed by making a void in the core of the bloom.The results show that due to the temperature gradient along the thickness direction of the bloom,the larger reduction rate is,the more obvious im-provement effect on the core region defects is.When the reduction rate is 33.3％,the void in the core of bloom is completely closed.The surface damage value of the bloom is lower than the critical damage value,and thus no new surface cracks are generated.
关键词
热芯大压下轧制/表面裂纹/孔洞压合/数值模拟/GCr15大方坯Key words
hot-core heavy reduction rolling/surface crack/void closure/numerical simulation/GCr15 bloom引用本文复制引用
出版年
2024
NETL
NSTL
万方数据