(北京工業(yè)大學 材料與制造學部，北京 100124)
摘 要: 攪拌摩擦增材制造(FSAM)是一種新型固態(tài)增材技術(shù)。逐層重復(fù)攪拌摩擦成型，是FSAM的顯著特點。在劇烈流動變形、熱力耦合作用下，母材晶粒逐層破碎細化，形成新的再結(jié)晶組織，最終形成增材成型構(gòu)件。以AZ31鎂合金板件FSAM為研究對象，首先建立多層薄板增材成型的計算流體力學仿真模型，研究轉(zhuǎn)速對材料流變、溫度場、應(yīng)變率的影響規(guī)律，并與實驗測量值對比驗證。其次計算增材區(qū)域鎂合金材料熱變形過程的Zener-Hollomon參數(shù)，利用經(jīng)驗公式法關(guān)聯(lián)Z參數(shù)與增材區(qū)再結(jié)晶晶粒尺寸。最終，結(jié)合1000 r/min轉(zhuǎn)速工況下的顯微硬度實驗測量結(jié)果，提出FSAM攪拌區(qū)再結(jié)晶組織顯微硬度的快速預(yù)測算法。結(jié)果表明：隨著增材板件層數(shù)增加，增材區(qū)平均晶粒尺寸減小，平均硬度值增大；隨攪拌頭轉(zhuǎn)速的增大，增材區(qū)材料的應(yīng)變率、再結(jié)晶晶粒尺寸都呈逐漸增大趨勢，顯微硬度呈下降趨勢。
關(guān)鍵字: 攪拌摩擦增材；數(shù)值模擬；晶粒尺寸；顯微硬度
（Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China）
Abstract:The friction stir additive manufacturing (FSAM) is a new solid-state manufacture technology. The re-stirring process is a remarkable feature of FSAM. Under the action of severe deformation and thermal coupling, the grains of base metal were crushed and refined layer by layer to form a new recrystallized structure, and finally an additive forming component was formed. AZ31 magnesium alloy sheet for FSAM process was taken as the research object. Firstly, computational fluid dynamics model of FSAM was established. The influence of rotation speed on material rheology, temperature field and strain rate was studied, and compared with the experimental results. Secondly, the Zener-Hollomon parameters of the hot deformation process of the magnesium alloy material in the additive zone were calculated. Then, the Z parameters and the recrystallized grain size of in additive zone were correlated by empirical formula method. Finally, combined with the micro-hardness test results at 1000 r/min, a fast prediction algorithm for the recrystallized microstructure of the FSAM was proposed. The results indicate that, with the increase of layers, the average grain size and the average hardness in the additive zone decrease. With the increase of the rotation speed, the strain rate and recrystallized grain size of the material in the additive zone gradually increase, but the micro-hardness shows a downward trend.
Key words: friction stir additive manufacturing; numerical simulation; grain size; micro-hardness
