Abstract

The design freedom offered by additive manufacturing (AM) enables the fabrication of components with internal surfaces that are challenging to access post-manufacture. This is of concern, as the surface condition can markedly deteriorate fatigue performance. Additionally, the adaptation of surface finishing methods for AM components with topologically optimized designs can be a costly practice. It is therefore desirable to consider deploying AM parts with no or minimal surface processing for targeted applications. This requires an in-depth understanding of the formation of various types of AM surfaces, including the variation in surface condition and controlling factors, and their influence on mechanical performance. The last few years have seen significant research advances in these aspects. Ti-6Al-4V is the most extensively studied alloy for AM. The research data available now allows an informative treatment of this topic for both practical applications and future research. Using laser powder bed fusion (LPBF) of Ti-6Al-4V as a model AM − alloy system, this article examines (i) the characteristics of various types of LPBF surfaces including horizontal, vertical, inclined, upward, downward, internal isolated, and slotted surfaces; (ii) the design features and LPBF variables that affect the surface topography; (iii) the capabilities of existing post-AM surface processing methods; and (iv) the influence of AM surface topography on mechanical properties by focusing on the fatigue performance. On this basis, design considerations are recommended for AM of consistent surfaces, and priority surface-related research issues are identified. The purpose is to establish an essential knowledge base for improved commercial designs for LPBF for suitable dynamically loaded applications, with no or minimal surface processing. While centering on LPBF of Ti-6Al-4V, the insights derived are expected to be applicable to other AM processes or metallic materials.

摘要

增材制造 (AM) 提供的设计自由度使制造具有内表面的组件成为可能，这些组件难以在制造后进行访问。这是令人担忧的，因为表面状况会显着降低疲劳性能。此外，采用拓扑优化设计的 AM 组件表面精加工方法可能是一种代价高昂的做法。因此，最好考虑为目标应用部署没有表面处理或表面处理最少的增材制造部件。这需要深入了解各种增材制造表面的形成，包括表面状况和控制因素的变化，以及它们对机械性能的影响。过去几年，这些方面的研究取得了重大进展。Ti-6Al-4V 是增材制造研究最广泛的合金。现在可用的研究数据允许对该主题进行信息处理，以用于实际应用和未来研究。本文使用 Ti-6Al-4V 的激光粉末床熔合 (LPBF) 作为模型 AM - 合金系统，研究 (i) 各种类型的 LPBF 表面的特性，包括水平、垂直、倾斜、向上、向下、内部隔离、和开槽表面；(ii) 影响表面形貌的设计特征和 LPBF 变量；(iii) 现有增材制造后表面处理方法的能力；(iv) 通过关注疲劳性能，增材制造表面形貌对机械性能的影响。在此基础上，建议对一致表面的 AM 进行设计考虑，并确定与表面相关的优先研究问题。目的是建立一个必要的知识库，用于改进 LPBF 的商业设计，以适用于合适的动态加载应用，无需表面处理或进行最少的表面处理。虽然以 Ti-6Al-4V 的 LPBF 为中心，但得出的见解有望适用于其他 AM 工艺或金属材料。