The elasto-plastic material behavior, material strength and failure modes of metals fabricated by additive manufacturing technologies are significantly determined by the underlying process-specific microstructure evolution. In this work a novel physics-based and data-supported phenomenological microstructure model for Ti-6Al-4V is proposed that is suitable for the part-scale simulation of selective laser melting processes. The model predicts spatially homogenized phase fractions of the most relevant microstructural species, namely the stable $\beta$-phase, the stable $\alpha_{\text{s}}$-phase as well as the metastable Martensite $\alpha_{\text{m}}$-phase, in a physically consistent manner. In particular, the modeled microstructure evolution, in form of diffusion-based and non-diffusional transformations, is a pure consequence of energy and mobility competitions among the different specifies, without the need for heuristic transformation criteria as often applied in existing models. The mathematically consistent formulation of the evolution equations in rate form renders the model suitable for the practically relevant scenario of temperature- or time-dependent diffusion coefficients, arbitrary temperature profiles, and multiple coexisting phases. Due to its physically motivated foundation, the proposed model requires only a minimal number of free parameters, which are determined in an inverse identification process considering a broad experimental data basis in form of time-temperature transformation diagrams. Subsequently, the predictive ability of the model is demonstrated by means of continuous cooling transformation diagrams, showing that experimentally observed characteristics such as critical cooling rates emerge naturally from the proposed microstructure model, instead of being enforced as heuristic transformation criteria.
翻译:由添加制造技术制造的金属的电磁塑料材料行为、材料强度和故障模式,在很大程度上是由特定流程的微结构演变决定的。在这项工作中,提议采用一个新的基于物理的和数据支持的Ti-6Al-4V 的细胞微结构模型,该模型适合选择性激光熔化过程的局部模拟。模型预测了最相关的微结构物种在空间上同质阶段的碎片,即稳定的 $-Beta美元阶段、稳定的 $\alpha}text{s}s $-production 阶段以及元化的马腾锡特特定过程的微结构特征,以物理上一致的方式进行。特别是,模型式微结构的演变,以基于扩散和非挥发性激光熔化过程的形式,是不同规定的能量和流动性竞争的纯粹结果,不需要经常适用于现有模型的超导变异模型。 以数学方式编制进化临界变异方方程式,使得模型适合于实际相关的温度假设或时间变异的马腾基变变法, 其成熟的变法基础的模型要求以自由基化的模型、任意的温度剖变制的模型, 温度图,其确定一个基础的模型的模型的模型的模型的模型的模型的模型的模型的模型, 其基础的模型的模型的模型的模型的模型的模型的模型的模型, 其基础的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的模型的