A multiscale approach to understand the role of dislocation motion on carbon mobility and the breakup of carbides in martensitic bearing steels.

一种多尺度方法，用于了解位错运动对马氏体轴承钢中碳迁移率和碳化物分解的作用。

• 批准号: 2444313
• 金额: --
• 依托单位: King's College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2444313
• 关键词: multiscale; approach; understand; role; dislocation

Plasticity in metals is mainly due to dislocation motion. The presence of carbon in steels hinders dislocation motion, leading to a stronger material and this strengthening effect depends on the carbon staying where it is. The decay of martensite under rolling contact fatigue (RCF) is thought to be due to carbon migration - it is the goal of this project to understand the role that dislocation motion plays in the redistribution of carbon under RCF.Results from atomistic simulations such as carbon dislocation binding energies will be used in the next stage of a multiscale approach featuring kinetic Monte Carlo (kMC) simulations of dislocations. From these simulations dislocation mobility rules can be extracted; i.e. functions that relate dislocation velocity to applied stress, temperature and solute concentration. The kMC simulations will also incorporate solute diffusion to ascertain how carbon moves with dislocations in different stress, temperature and concentration regimes. The results of the kMC simulations can be used in a more course-grained approach called discrete dislocation dynamics (DDD) where multiple dislocations and their interactions are simulated. From this approach it is possible to calculate the stress produced in a crystal under a variety of straining conditions. However, it may not be necessary to use DDD if the kMC code developed in this project is successful in simulating multiple dislocations.

金属的塑性主要是由于位错运动引起的。钢中碳的存在阻碍了位错运动，导致更强的材料，这种强化效果取决于碳留在原地。在滚动接触疲劳（RCF）下马氏体的衰变被认为是由于碳迁移-这是本项目的目标，以了解的作用，位错运动在RCF下的碳的再分布。原子模拟的结果，如碳位错结合能将被用于下一阶段的多尺度方法，具有动力学蒙特卡罗（kMC）模拟位错。从这些模拟中可以提取位错迁移率规则;即，将位错速度与施加的应力、温度和溶质浓度相关联的函数。kMC模拟还将包括溶质扩散，以确定碳在不同应力、温度和浓度状态下如何随位错移动。kMC模拟的结果可以用于更粗粒度的方法，称为离散位错动力学（DDD），其中模拟多个位错及其相互作用。用这种方法可以计算在各种应变条件下晶体中产生的应力。然而，如果本项目中开发的kMC代码成功地模拟了多位错，则可能没有必要使用DDD。