大型復雜梯度材料高性能鈦合金構件激光近凈基礎研究報告

張凌云 湯海波 王向明 王華明 田象軍

摘 要：激光快速成形技術是一項“變革性”的無模、短流程、短周期、低成本、數字化、“近凈成形”先進制造技術，特別是為大型復雜梯度材料高性能鈦合金構件的制造提供了可行途徑。為提高我國航空航天等領域裝備研制生產能力、縮短研制生產周期和降低生產成本，本研究采用激光成形技術開展了大型復雜梯度材料高性能鈦合金構件的制造和基礎研究。主要結果如下： （1）基于組織梯度高性能鈦合金構件制造，完成了激光成形鈦合金移動熔池（基本單元）非平衡快速凝固形核和生長行為研究，建立激光成形大型復雜梯度鈦合金構件凝固組織晶粒形態控制技術，為組織梯度高性能鈦合金構件激光近凈成形制造奠定了理論基礎和提供了工藝控制方法。（2）基于鈦合金梯度結構材料設計基本原則，面向飛機框梁、發動機整體葉盤等大型復雜關鍵鈦合金構件需求，設計三類梯度結構材料體系：高強/低強（TA15/TA2）、中強/高強（TC4/TC11、TA15/TC11）、高強/高損傷容限（TC18/TC21），開展合金過渡區域顯微組織、化學成分、顯微硬度梯度變化規律研究，并測試了其拉伸等基本力學性能。（3）基于激光成形梯度鈦合金構件熱處理工藝匹配及通過熱處理挖掘材料性能潛力的目標，在已有激光成形TA15鈦合金熱處理工藝研究基礎上，完成了激光成形TC11、TC4、TC18等鈦合金固態相變行為研究，掌握非平衡熱處理特種雙態顯微組織形成機理及其控制方法，為激光成形梯度鈦合金構件熱處理工藝制度制定和構件綜合性能優化提供了理論指導與技術途徑。（4）基于梯度過渡區的研究，提出設計并激光成形制備出了TA15/TA2、TC4/TC11、TC18/TC21等梯度鈦合金構件的過渡區新型鈦合金材料，開展其顯微組織、化學成分、力學性能等分析測試，為梯度過渡區的優化設計提供了理論指導和實驗數據支撐。（5）開展了激光成形高性能梯度鈦合金構件力學性能評價研究，初步制定試驗大綱，開展部分性能測試和斷裂機理研究。

關鍵詞：激光成形 鈦合金 梯度材料

Abstract：In order to improve production capacity of the equipment in China's aeronautics and astronautics industry， shorten the production cycle and reduce the cost of production，the laser forming is applied to fabricate the large complex high-performance graded titanium alloy structural components，and the basic research is carried out in the present project. The main findings can be summarized as follows：（1）Based on the purpose of fabricating titanium alloy with graded microstructure， the investigation about the unique non-equilibrium rapidly solidified structures （including nucleation and growth behavior） during laser forming process is carried out.According to the investigation，the technologies of controling solidified structures are developed，which provide the theoretical basis and the methods for laser forming titanium alloy with graded microstructure.（2）Based on designing principles of graded titanium alloy structural components， and according to the requirement of the large complex graded titanium alloy structural components in aircraft beam frame，bisk of aeroengine etc，three types of graded titanium alloy structural components were designed， including high strength/low strength（TA15/TA2），medium strength/high strength （TC4/TC11、TA15/TC11） and high strength/high damage tolerance（TC18/TC21）. The graded microsturcture，chemical composition and microhardness in the graded transitional region of these alloys are studied.（3）Based on the purpose of improving the mechanical properties of the graded titanium alloy by optimize heat treatment，the solid-state phase transformation during heat treatment in laser forming TA15，TC11，TC4，TC18 etc.were investigated. An unique bi-modal microstructure is obtained，and its formation mechanism is revealed，which shed light on improving the mechanical properties of the graded titanium alloy by heat treatment.（4）To investigate details of the graded transitional region，the TA15/TA2，TC4/TC11 and TC18/TC21 mixed titanium alloys are designed and fabricated.The mircostructures，chemical composition and mechanical properties are investigated， which shed light on the optimization design of the graded transitional region.（5）The comprehensive mechanical properties of laser near-net forming graded titanium alloy are investigated.The experimental program has been established， and parts of mechanical properties have been tested. Furthermore，the fracture mechanism of the graded titanium alloy is studied.

Key Words：Laser forming；Titanium alloy；Gradient material

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