铁素体/马氏体双相钢拉伸变形过程中应力应变不均匀性分析

Analysis of Stress and Strain Inhomogeneity During the Tensile Deformation ofFerrite/Martensitic Dual Phase Steel

以铁素体/马氏体双相钢为研究对象,经轧制及热处理后进行变形量为5%的拉伸实验,借助配有EBSD成像系统的场发射扫描电镜对实验钢塑性变形后的微区取向进行分析,并结合晶体塑性模拟DAMASK软件模拟其塑性变形行为。结果表明,经轧制变形获得的铁素体/马氏体双相钢,两相应力应变分配不均匀。实验钢中马氏体积累了更多的位错,KAM值更大。临近马氏体区域的铁素体基体Schmid因子更大,可达到0.49,在塑性变形过程中容易优先产生位错和滑移。晶体塑性模拟结果表明,变形初期,铁素体需承担较大的应变、马氏体承担应力以协调整体的变形。当拉伸变形继续发生时,两相应力应变分布的不均匀性将导致两相交界以及晶界处最先发生断裂。

In the present work,the ferrite/martensite dual-phase steel was taken as the research object.After rolling and heat treatment,the tensile test with a deformation of 5%was performed.The field emission scanning electron microscope equipped with EBSD imaging system was utilized to analyze the micro-area orientation of the experimental steel after plastic deformation,and the plastic deformation behavior was simulated by combining the crystal plasticity simulation DAMASK software.The results showed that the two corresponding stress-strain distribution of ferrite/martensite dual-phase steel obtained by rolling deformation was uneven.The martensite accumulated more dislocations in the experimental steel,and the KAM value was larger.The Schmid factor of ferrite matrix near the martensite region was larger than 0.49,and dislocations and slips were prone to occur preferentially during elastic deformation.The consequences of crystal plasticity simulation showed that at the beginning of deformation,ferrite needed to bear large strain and martensite needed to bear stress to coordinate the overall deformation.When the tensile deformation continues to occur,the inhomogeneity of the two analogous force-strain distribution will lead to the first fracture at the two-phase boundary and at the grain boundary.