Fatigue in precipitation hardened materials: a three-dimensional discrete dislocation dynamics modelling of the early cycles
Fatigue in precipitation hardened materials: a three-dimensional discrete dislocation dynamics modelling of the early cycles
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DOI：
10.1080/14786430701393159
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发表时间：
2007-07
影响因子：
1.6
通讯作者：
C. Shin;C. Robertson;M. Fivel
中科院分区：
文献类型：
--
作者：
C. Shin;C. Robertson;M. Fivel
沉淀硬化金属的三维位错动力学（DD）疲劳模拟是数值发展方面的一个主要挑战。几个沉淀配置已被调查的原始处理的沉淀位错相互作用和并行DD代码。在含有单一尺寸的可剪切颗粒（RP = 160 nm）的晶粒中，应变被定位在清晰的带中，其中沉淀物被完全剪切掉。疲劳行为包括初始硬化，随后是严重的循环软化和显著的表面滑移不可逆性。在大的单一尺寸的颗粒（r p = 400 nm）的存在下，持久的滑移带（PSB）结构伴随着高度可逆的表面位移。滑移频散来源于奥罗万环，对力学响应的影响很小。双峰分布的力学行为介于上述两种情况之间，上述微观结构特征在同一晶粒内共存。与单峰大颗粒的情况不同，在单峰大颗粒的情况下，所有的颗粒保持其初始强度，双峰分布的一些大颗粒经历了显着的强度降低。
Three-dimensional dislocation dynamics (DD) fatigue simulations in precipitation hardened metals is a major challenge in terms of numerical development. Several precipitate configurations have been investigated with an original treatment of precipitate–dislocation interactions and a parallelized DD code. In grains containing single-sized shearable particles (r p = 160 nm), strain is localized in clear bands where the precipitates are totally sheared-off. The fatigue behaviour involves an initial hardening followed by severe cyclic softening and significant surface slip irreversibility. In the presence of large single-sized particles (r p = 400 nm), the persistent slip band (PSB) structure is accompanied by highly reversible surface displacements. Slip dispersion originates from Orowan loops that have little effect on the mechanical response. The mechanical behaviour of a bimodal distribution is intermediate between the two above cases with the above microstructural features coexisting within the same grain. Unlike in the monomodal large-particle case, where all the particles retain their initial strength, some of the large particles of the bimodal distribution undergo a significant strength reduction.