Dislocation pile-up and cleavage: effects of strain gradient plasticity on micro-crack initiation in ferritic steel
Dislocation pile-up and cleavage: effects of strain gradient plasticity on micro-crack initiation in ferritic steel
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DOI：
10.1007/s10704-018-0313-8
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发表时间：
2018-11-01
影响因子：
2.5
通讯作者：
Huetter, G.
中科院分区：
文献类型：
--
作者：
Giang, N. A.;Seupel, A.;Huetter, G.
铁素体钢中的微裂纹通常源于破碎或脱粘的碳化物颗粒，或源于铁素体基体的解理。文献中的实验表明，铁素体钢中的微裂纹主要是由晶界或颗粒处的位错堆积引起的。另一方面，铁素体也可以阻止形核微裂纹，由于局部塑性变形，这降低了裂纹尖端的应力。在本研究中，这些机制之间的竞争进行了研究，使用有效的梯度塑性（标量梯度塑性）的铁素体的细胞模型模拟。该理论允许通过合适的界面条件来模拟位错堆积。铁素体的潜在分裂或碳化物的失效由内聚区模拟。参数的研究进行相对于颗粒的大小和强度的铁素体和碳化物。
Micro-cracks in ferritic steel often originate from broken or debonded carbide particles, or from cleavage of the ferrite matrix. Experiments in literature show that dislocation pile-ups at grain boundaries or particles predominantly induce micro-cracks in ferritic steel. On the other hand, the ferrite can also arrest nucleated micro-cracks owing to local plastic deformations which reduce the stresses at the crack tip. In the present study, the competition between these mechanisms is investigated by cell model simulations using effective gradient plasticity (scalar gradient plasticity) for the ferrite. This theory allows to model the dislocation pile-up by suitable interface conditions. Potential cleavage of the ferrite or failure of the carbide is modelled by a cohesive zone. Parameter studies are performed with respect to the size of the particle and the strengths of ferrite and carbide.