Three-dimensional finite element analysis of representative volume elements for characterizing the effects of martensite elongation and banding on tensile strength of ferrite-martensite dual-phase steels
Three-dimensional finite element analysis of representative volume elements for characterizing the effects of martensite elongation and banding on tensile strength of ferrite-martensite dual-phase steels
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DOI：
10.1016/j.ijmecsci.2019.105133
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发表时间：
2019-11-01
影响因子：
7.3
通讯作者：
Alves, Luis
中科院分区：
文献类型：
--
作者：
Matsuno, Takashi;Yoshioka, Tomoya;Alves, Luis
在这项研究中，我们数值分析了马氏体伸长率的影响（即，通过三维有限元分析，对双相钢的宏观应力-应变曲线和微观损伤演化进行了研究，以获得设计更高韧性、更高强度双相钢的见解。代表性的体积元素（RVE）组成的等轴，细长，带状马氏体晶粒嵌入在铁素体基体的模拟。一个修改的Voronoi图技术被应用到产生这些虚拟的马氏体晶粒的RVE。分析表明，等轴马氏体集中应变在某些部分的铁素体相，而马氏体伸长率造成均匀的应变集中在铁素体相，这反过来，作为一个新产生的硬相。因此，拉伸强度低于等轴晶粒。另一方面，马氏体带状并没有降低铁素体应变集中，但诱发马氏体晶粒中的高度应变分配。这种行为导致在整个应变区域内（包括峰值处）出现显著高的屈服应力。马氏体伸长也导致马氏体晶粒中的高度损伤。然而，细长的马氏体带表现出光滑的表面，几乎没有凹陷。这些带防止损伤集中在马氏体拉伸和带状，在对比的情况下，带状的等轴马氏体晶粒。
In this study, we numerically analyzed the effects of martensite elongation (i.e., fibering) and banding on the macroscopic stress-strain curves and microscale damage evolution in dual-phase (DP) steels using three-dimensional finite element analyses to obtain insights into designing more ductile, higher-strength DP steels. Representative volume elements (RVEs) composed of equiaxed, elongated, and banded martensite grains embedded within a ferrite matrix were employed for the simulations. A modified Voronoi diagram technique was applied to generate these virtual martensite grains in the RVEs. The analyses revealed that equiaxed martensite concentrated strain in certain parts of the ferrite phase, whereas martensite elongation caused a homogenous strain concentration in the ferrite phase, which, in turn, acted as a newly generated hard phase. Therefore, the tensile strength was lower than for equiaxed grains. On the other hand, martensite banding did not decrease the ferrite -strain concentration, but induced a high-degree of-strain partitioning in the martensite grains. This behavior resulted in remarkably high yield stresses over the entire strain region, including at the peak values. Martensite elongation also resulted in a high degree of damage in the martensite grains. Nevertheless, the elongated martensite bands exhibited smooth surfaces with few concavities. These bands prevented damage concentration during martensite elongation and banding, in contrast to the case for the banding of the equiaxed martensite grains.