An integrated (ICME) approach to multiscale modelling of the fabrication and joining of powder processed parts

基于金属粉末的生产方法如HIP或增材层制造（ALM）的适用性受到无法以足够的精度限定工艺参数以提供工业生产所需的质量的限制。类似地，部件制造所需的连接技术的实施受到缺乏对相关合金系统中发生的气-液相相互作用和固态相变的影响的理解的限制。基于实际试验和物理评估的传统解决方案既昂贵又耗时，并且对于能源和推进工业中遇到的长使用寿命来说是不可行的，而基于经验的现象学建模方法不能提供所需的保真度。为了解决这些工业需求的多尺度建模方法相结合的实验验证与材料建模的应用，在短的长度尺度需要捕捉相关的物理，以及技术的发展，将预测的行为在一个一致的方式在更高的长度尺度应用到组件级模拟。多尺度模型集成将包括许多组成部分，从焊接和增材制造中的短长度尺度流体流动和液体/气体相互作用的基于新多物理场的计算流体动力学计算开始。这些将提供孔隙形成的数据，将结合细胞自动机预测的晶粒结构。将开发新的方法来联合收割机这种精细尺度的数据结合在基于晶体塑性框架的有限元中，以定义代表性的体积单元，用于模拟部件应力分析中的宏观行为。部件级模拟工作将建立在Smith教授的EPSRC制造奖学金的基础上。通过利用所获得的关于焊接所施加的微观结构变化的影响的知识，高完整性焊接技术的寿命方法。这些对焊缝的抗使用中退化性和对裂纹存在的敏感性有深远的影响。研究项目中316L不锈钢的显微组织特征数据也将为模型验证提供基础。本项目发展的一个关键部分将是从典型的单值确定性模型扩展到基于统计的材料性能和工艺可变性描述。这是一项具有挑战性的活动，但建模工具必须能够预测在真实的材料中看到的散射。一个成功的解决方案不仅会产生新的科学，但显然会导致概率寿命方法的发展与风险为基础的决策有明显的好处，为行业的输出。这种方法提供了前景，更好地了解在服务性能的组件和焊缝在现有的英国核反应堆舰队和任何工业部门的长期结构性能是important. Similarly的发展，在美国已经导致了一个新的领域称为集成计算材料工程（ICME）。这是一种多学科的产品设计方法，具有巨大的经济潜力，ICME的成功实施将彻底改变组件的设计和制造方式。本提案将针对316 L不锈钢热等静压和TIG焊接部件的工业演示器，采用基于ICME的方法解决建模和设计挑战。由航空航天和能源行业合作伙伴提供的演示器将展示不同市场领域可以实现的好处。拟议的方案将是英国首次尝试在大型工业规模的演示器上使用ICME工具。

The applicability of metallic powder based production methods such as HIP or additive layer manufacturing (ALM) are restricted by an inability to define the process parameters with sufficient accuracy to provide the quality required for industrial production. Similarly the implementation of the joining technologies needed for component fabrication is limited by a lack of understanding of both the gas-liquid phase interactions and the effect of the solid state phase transformations that occur in the relevant alloy systems. Traditional solutions, based on practical trials and physical assessment, are both costly and time consuming and for the long service lives encountered in the energy and propulsion industries are not feasible while empirically based phenomenological modelling approaches cannot provide the required fidelity. To address these industrial needs a multiscale modelling approach is proposed which combines experimental validation with the application of materials modelling, at the short length scales required to capture the relevant physics, together with the development of techniques to incorporate the predicted behaviour in a consistent manner at higher length scales for application to component level simulations. The multiscale model integration will consist of a number of component parts commencing with new multiphysics based computational fluid dynamics calculations of the short length scale fluid flow and liquid/gas interactions in welding and additive manufacturing. These will provide data on porosity formation which will be combined with cellular automata predictions of grain structure. Novel methods will be developed to combine this fine scale data in a finite element based crystal plasticity framework to define representative volume elements for modelling the macroscopic behaviour in component stress analysis.The component level simulation work will build upon the EPSRC Manufacturing Fellowship of Prof Smith on a whole-life approach to high integrity welding technologies by utilising the knowledge gained on the effect of the microstructural changes imposed by welding. These have a profound influence on a weld's resistance to in-service degradation and upon its sensitivity to the presence of cracking. The microstructural characterisation data available on 316L stainess steel from the Fellowship work will also provide a basis for the model validation.A key part of the developments in this project will be the extension, from typical single value deterministic models, to statistically based descriptions of material properties and process variability. This is a challenging activity but it is essential that modelling tools become capable of predicting the scatter that is seen in real materials. A successful solution will not only generate novel science but will clearly lead to the development of probabilistic lifing methods with risk based outputs for decision making which have clear benefits for industry. This approach provides the prospect of a better understanding of in-service performance of components and welds in both the existing UK nuclear reactor fleet and in any industrial sector where long term structural performance is important.Similar developments in the US have led to a new field known as Integrated Computational Materials Engineering (ICME). This is a multi-disciplinary approach to product design that offers huge economic potential and the successful implementation of ICME will revolutionise the way components are being designed and manufactured. This proposal will address the modelling and design challenge using an ICME based approach on industrial demonstrators of 316L stainless steel HIPped and TIG welded parts. The demonstrators, supplied by the partners from the aerospace and energy industries, will show the benefits that can be achieved in different market sectors. The proposed programme will be the first attempt in the UK to use ICME tools on large industrial scale demonstrators.