Influential factors on the deformability of colonies in pearlitic steel
Influential factors on the deformability of colonies in pearlitic steel
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DOI：
10.1016/j.matchar.2021.111197
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发表时间：
2021-05
影响因子：
4.7
通讯作者：
Yuto Yajima;N. Koga;C. Watanabe
中科院分区：
文献类型：
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作者：
Yuto Yajima;N. Koga;C. Watanabe
利用数字图像相关技术对珠光体钢拉伸变形过程中应变的不均匀分布进行了可视化处理，并对变形过程中珠光体的形貌进行了定量评价。在块体边界附近引入了高应变。在块体内部，应变分布不均匀。与球化程度相关的菌落长度与菌落大小的比率（Lcem/Lcol）与菌落内的平均应变具有良好的相关性;球化菌落表现出相对较高的应变。然而，尽管Lcem/Lcol值几乎相同，但引入菌株的值在很大程度上分散在菌落中。根据Lcem/Lcol值，将菌落分为球化菌落、部分球化菌落和层状菌落。在大多数层状菌落中，引入的应变低于平均应变，并且在位于块边界附近的菌落中倾向于更高。另一方面，对于部分球化的殖民地，引入的应变的值变化很大，并充分相关的施密德因子（SFLF_min）的滑移系统，其中位错可以滑动长距离而不中断的位错板。此外，发现滑移传播穿过菌落边界的困难影响部分球化菌落的变形能力。在3种类型的团簇中，球化团簇的应变最大，且与离块体边界的距离或SFLF_min无关。因此，球化程度是影响珠光体钢中团簇变形能力的主要因素。同时，SFLF_min、与块体边界的距离以及滑移传播穿过殖民地边界的难度充分影响菌落的变形能力，导致具有相等Lcem/Lcol值的菌落的应变值变化。
The inhomogeneous strain distribution introduced by the tensile deformation of pearlitic steel was visualized using digital image correlation method, and the morphology of cementite was quantitatively evaluated. The high strain was introduced near the block boundaries. Within the blocks, the strain was inhomogeneously distributed. The ratio (Lcem/Lcol) of cementite length to colony size, which is related to the degree of spheroidization, was well correlated with the average strain within the colonies; spheroidized colonies exhibited a relatively high strain. However, although theLcem/Lcolvalues were nearly identical, the values of the introduced strain were largely dispersed in the colonies. Based on theLcem/Lcolvalues, the colonies were classified as spheroidized, partially-spheroidized, and lamellar colonies. In majority of the lamellar colonies, the introduced strain was lower than the average strain and tended to be higher in the colonies located near the block boundaries. On the other hand, for the partially-spheroidized colonies, the values of the introduced strain varied considerably and were sufficiently correlated with the Schmid factor (SFLF_min) for slip system, where dislocations can glide long distances without interrupting the cementite plate. Additionally, the difficulty of slip propagation across colony boundaries was found to affect the deformability of the partially-spheroidized colonies. The spheroidized colonies exhibited the highest strain among the three types of colonies and were not correlated with the distance from the block boundary orSFLF_min. Therefore, it was concluded that the degree of spheroidization was the main influence on the deformability of the colonies in the pearlitic steel. Meanwhile, theSFLF_min, distance from the block boundary, and difficulty of slip propagation across the colony boundary sufficiently affected the deformability of the colonies, causing variation in the strain value for colonies with equalLcem/Lcolvalues.