Mechanical properties of thin wall specimens produced by additive manufacturing methods

添加剂制造(AM)技术为加拿大的经济和社会带来了新的机遇。它可以促进许多部门生产坚固、轻便的产品，包括航空航天和生物医学，并允许进行以前的制造技术无法实现的设计。AM对铝和钛合金非常感兴趣，因为它们是相对昂贵的金属，AM可以最大限度地减少传统铸造、锻造和机械加工过程中产生的材料浪费。对于薄壁的具体问题，随着截面尺寸的减小，表面敏感性(即表面光洁度)对性能的影响更大，此外，由于特征尺寸较小，薄壁受到来自周围粉床的更显著的散热。因此，AM工艺产生的薄壁特征通常包括未熔化的粉末夹杂物、内部空洞、裂纹和形状不规则等缺陷。表面AM后处理技术通过去除和/或光滑表面，或诱导所需的表面形态或降低拉伸表面的残余应力，来解决与已建AM材料表面的不规则形态和随机放置特征相关的问题。因此，这项合作的目标是了解粉末特性和AM工艺变量的影响，以及AM成型后处理对薄壁尺寸部件的添加制造(AM)的影响，最终目标是能够设计出具有最理想特性的粉末，用于通过激光-粉末床融合(L-PBF)和粘结剂喷射工艺制造的此类AM成型。由于这个项目将由两名博士生完成，另一个主要成果将是增加魁北克和加拿大的AM技术基础。该项目是麦吉尔大学、粉末制造公司A P and C和加拿大高分辨率3D打印机、金属3D部件制造商Nanogrande的合作项目，也是第一个采用金属粉末纳米添加剂制造技术的项目。这三家公司都已经有了强大的合作，这个项目将很容易地建立在这个基础上。

Additive manufacturing (AM) technology opens new opportunities for the economy and society of Canada. It can facilitate the production of strong, light-weight products for many sectors, including aerospace and biomedical, and it allows designs that were not possible with previous manufacturing techniques. Aluminum and titanium alloys are of great interest for AM since these are relatively expensive metals and AM can minimize the waste of material that is generated by traditional casting, forging and machining routes. Regarding the specific problem of thin walls, as section size decreases, surface sensitivity, i.e., surface finish, is much more influential on the properties In addition, due to the small feature dimensions, the thin walls are subjected to more significant thermal dissipation from the surrounding powder beds. As a result, thin features generated by AM processes often include defects such as un-melted powder inclusions, internal voids, cracks, and shape irregularities. Surface post-AM-processing techniques tackle the issues associated with the irregular morphology and the randomly positioned features on the surface of as-built AM material, by removing and/or smoothing the surface, or inducing a desired surface morphology or reducing the tensile surface residual stress. The goal of this partnership is therefore to understand the effect of powder characteristics and AM process variables and post AM build treatments on the additive manufacturing (AM) of components with thin wall dimensions, the ultimate goal being to be able to design powders with the most desirable characteristics for such AM builds made by laser- powder bed fusion (L-PBF) and binder jet processes. Since this project will be performed by 2 Ph.D. students, another major outcome will be to increase the AM technological base in Quebec and Canada. The project is a collaboration between McGill University, A P and C, a powder manufacturing company, and Nanogrande, a Canadian based manufacturer of high-resolution 3D printers, metal 3D parts and the first with nano additive manufacturing technology with metal powders. All three already enjoy strong collaborations and this project will readily build on this foundation.