钒对激光熔化沉积钛合金组织及性能的作用机制  

Mechanism of Vanadium on Microstructure and Properties of Titanium Alloy by Laser Melting Deposition

作　　者：刘晏硕 徐诺 徐国建[1] 杨楠 王辰阳 邢飞 Liu Yanshuo;Xu Nuo;Xu Guojian;Yang Nan;Wang Chenyang;Xing Fei(School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110870,Liaoning,China;Department of Development Reform and Discipline Construction,Shenyang University of Technology,Shenyang 110870,Liaoning,China;School of Mechanical Engineering,Shenyang University of Technology,Shenyang 110870,Liaoning,China)

机构地区：[1]沈阳工业大学材料科学与工程学院,辽宁沈阳110870 [2]沈阳工业大学发展改革与学科建设处,辽宁沈阳110870 [3]沈阳工业大学机械工程学院,辽宁沈阳110870

出　　处：《中国激光》2022年第14期58-67,共10页Chinese Journal of Lasers

基　　金：辽宁省“兴辽英才计划”(XLYC1902022);沈阳市关键核心技术攻关专项(20-202-1-10)。

摘　　要：本文通过在TC4中添加一定质量分数的钒元素(2%,4%,6%,8%,10%),研究了钒对激光熔化沉积(LMD)钛合金沉积态显微组织、相组成及力学性能的作用机制。结果表明,随着V含量的增加,沉积方向(Z方向)的原始β柱状晶晶粒尺寸逐渐减小,沉积层底部柱状晶平均宽度从1 mm(TC4+0%V)左右减小到0.24 mm(TC4+10%V),且沿Z方向组织存在逐渐向等轴晶转化的趋势;不同V含量的沉积态样件组织均由大量密排六方结构α-Ti(α)相和少量体心立方结构β-Ti(β)相构成,而β相的相对含量(质量分数)随着V含量的增加,由0.83%(TC4+0%V)逐渐提高到30.91%(TC4+10%V)。另外,随着V含量的增加,初生针状α组织逐渐细化,并更加趋向于等轴晶。添加V能够明显提高沉积态样件的抗拉强度,但塑性在一定程度上有所降低;当V元素添加量为6%时,沉积态样件的综合力学性能最佳,抗拉强度约为1018 MPa,屈服强度约为892 MPa,伸长率约为11.2%,均超过了TC4锻件标准;不同V含量的沉积态样件断口上均布满了韧窝,均为塑性断裂。Objective TC4(Ti-6Al-4V)alloy has high specific strength,corrosion resistance and excellent mechanical properties,which is often used in the aerospace field as structural materials.However,titanium(Ti)alloy manufacturing by the traditional methods has not only high cost and long cycle,but also low utilization rate of materials.In recent years,the laser additive manufacturing(LAM)technology has been used to replace the forging process,and good results have been achieved in the near net forming of Ti alloy structural parts in the aerospace field.The laser melting deposition(LMD)technology usually takes metal powder as raw material and uses a high-energy laser beam to make the powder rapidly melt and accumulate layer by layer,and thus the goal of fast near-net forming of dense and high-performance large complex metal components is achieved.However,in the process of LMD manufacturing Ti alloy,there exists a large temperature gradient between the molten pool and the substrate,and thus the thick columnar crystals grow through multiple sedimentary layers along the direction of temperature gradient,resulting in poor mechanical properties and other problems.Therefore,the deposited structure of TC4 can be regulated by alloying to improve its mechanical properties and avoid problems such as high manufacturing cost,long production cycle,and difficulty in the heat treatment of large structural parts.A large number of studies have shown that the composition,phase composition,grain size and phase distribution of alloys have important effects on the mechanical properties of alloys.However,the effect of V on the microstructure and properties of as-deposited TC4 in the additive manufacturing process is rarely reported so far.In this paper,the effect of V content on the microstructures and properties of Ti alloys is studied,and the optimal addition amount of V is discussed,which provides a theoretical basis for further improving the comprehensive properties of Ti alloys by LDM.Methods The size of the test substrate TC4 is 200 mm×1

关 键 词：激光技术 激光熔化沉积 钛合金 沉积态 显微组织 力学性能 

分 类 号：TG401[金属学及工艺—焊接]