大型复杂梯度材料高性能钛合金构件激光近净基础研究报告

Basic Research on Laser Near-net Forming of Large Complex High-performance Graded Titanium Alloy Structural Components: An Interim Report

激光快速成形技术是一项"变革性"的无模、短流程、短周期、低成本、数字化、"近净成形"先进制造技术,特别是为大型复杂梯度材料高性能钛合金构件的制造提供了可行途径。为提高我国航空航天等领域装备研制生产能力、缩短研制生产周期和降低生产成本,本研究采用激光成形技术开展了大型复杂梯度材料高性能钛合金构件的制造和基础研究。主要结果如下:(1)基于组织梯度高性能钛合金构件制造,完成了激光成形钛合金移动熔池(基本单元)非平衡快速凝固形核和生长行为研究,建立激光成形大型复杂梯度钛合金构件凝固组织晶粒形态控制技术,为组织梯度高性能钛合金构件激光近净成形制造奠定了理论基础和提供了工艺控制方法。(2)基于钛合金梯度结构材料设计基本原则,面向飞机框梁、发动机整体叶盘等大型复杂关键钛合金构件需求,设计三类梯度结构材料体系:高强/低强(TA15/TA2)、中强/高强(TC4/TC11、TA15/TC11)、高强/高损伤容限(TC18/TC21),开展合金过渡区域显微组织、化学成分、显微硬度梯度变化规律研究,并测试了其拉伸等基本力学性能。(3)基于激光成形梯度钛合金构件热处理工艺匹配及通过热处理挖掘材料性能潜力的目标,在已有激光成形TA15钛合金热处理工艺研究基础上,完成了激光成形TC11、TC4、TC18等钛合金固态相变行为研究,掌握非平衡热处理特种双态显微组织形成机理及其控制方法,为激光成形梯度钛合金构件热处理工艺制度制定和构件综合性能优化提供了理论指导与技术途径。(4)基于梯度过渡区的研究,提出设计并激光成形制备出了TA15/TA2、TC4/TC11、TC18/TC21等梯度钛合金构件的过渡区新型钛合金材料,开展其显微组织、化学成分、力学性能等分析测试,为梯度过渡区的优化设计提供了理论指导和实验数据支撑。(5)开展了激光成形高性能梯度钛合金构件力学性能评价研究,初步制定试验大纲,开展部分性能测试和断裂机理研究。

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 hlgh--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：（｜） 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.Aocording 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/TCII.TAIS/TCll） and high strength/high damage tolerance（TCt8/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 ere.were investigated. An unique hi--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.