Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V界面反应

在1.8 ks、1 073～1 173 K条件下对Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V进行了钎焊试验.通过扫描电镜、波谱、能谱和X射线衍射对界面反应产物进行了测试,确定了界面结构,并讨论了这些反应产物形成的可能性.结果表明,温度小于1 123 K的界面结构为Al2O3/Cu2Ti4O/Cu4Ti3+Cu固溶体/Ag-Cu共晶 + 富Ag相;温度1 173 K的界面结构为Al2O3/Cu3TiO5 + CuAl2O4/Cu4Ti3/富Ag相+ Cu4Ti3.     

Ti-6Al-4V真空钎焊研究

针对目前用于Ti合金钎焊的Ti基钎料熔点偏高的现状，设计了Ti-Zr-Cu-Ni钎料，结果 表明，接头强度较高，因钎焊温度较低母材基本上保留了原始组织。同时还证明Ti-Zr-Cu钎料大幅度增加Cu的质量分数易造成钎缝中心区域生成连续分布的Ti2Cu+TiCu，严重影响接头强度。     

固态渗碳化硼对Ti-6Al-4V显微组织和性能的影响

研究了Ti-6Al-4V在800℃和1000C下固态渗碳化硼20h后的渗层显微组织以及对硬度等的影响。结果表明：渗层在表面为致密分布的化合物层,其成分主要为TiC、TiB以及TiB2等硬质相,而在基体内部则形成沿晶界分布的板条状或等轴状的颗粒扩散层;表面碳化硼处理可以显著提高Ti-6Al-4V的表面硬度,由359HV提高到了664HV,并且可以得到良好的表面硬、芯部软的硬度梯度;断口形貌分析发现材料由韧性断裂转变成脆性断裂。     

砂带干式磨削Ti-6Al-4V钛合金的磨削力

对砂带干式磨削Ti-6Al-4V钛合金的的磨削力进行了测试,分析了磨削参数对磨削力的影响;用动态测力仪、三维体式显微镜、粗糙度仪和显微硬度计对磨削试样表面质量进行了分析,提出了砂带磨削工艺参数的优化方案。结果表明:在砂带干式磨削条件下,磨削力随着磨削深度和工作台进给速度的增大而增加,随着砂带线速度的提高而减小;在砂带线速度为15 m.s-1,工作台进给速度为315 mm.min-1,磨削深度为0.025~0.1 mm时,合金表面粗糙度Ra≤0.35μm。     

无涂层硬质合金刀具车削钛合金Ti-6Al-4V实验研究

钛合金是航空航天工业中应用广泛的一种难加工材料。本文研究了无涂层硬质合金刀具干切削钛合金Ti-6Al-4V时切削力、表面粗糙度的变化规律，得到了切削深度、进给量、切削速度对切削力和表面粗糙度的影响规律。对切削力实验结果进行了回归分析得到了切削力的指数公式，并运用校正R^2拟合判定系数、累积概率图和残差图对回归模型进行了检验，检验结果表明：切削力的3个回归方程较好的拟合了实验所测的数据，钛合金切削过程中切削力近似满足指数关系。     

置氢对Ti-6Al-4V合金组织和性能的影响

为掌握置氢改善钛合金切削性能的机理,利用光学显微镜与X射线衍射仪分析了置氢Ti-6Al-4V合金的显微组织,采用热膨胀仪与热常数测试仪测定了该合金的热膨胀系数和导热系数,通过高温拉伸试验研究了该合金的力学性能。结果表明:置氢后,随着氢含量的增加,合金中的β相比例提高,并且生成了δ氢化物;与未置氢钛合金相比,在900℃时的热膨胀系数最大降幅为6%,而导热系数在500℃时的增幅最大,为40%;置氮后的钛合金,在800℃时抗拉强度与伸长率的降幅分别为19%和74%。     

激光参数对Ti-6Al-4V粉末SLM成形质量的影响

为了在金属3D打印产品中获得合适的加工参数,提高金属成形件的产品性能,利用有限元方法对Ti-6Al-4V粉末激光选区熔化（SLM）成形进行模拟。以APDL编程语言建模,逐步施加热源获得成形件的温度场,通过熔池演变研究了Ti-6Al-4V粉末SLM成形过程中材料接合情况;以温度场为载荷研究了SLM成形的应力场和位移场。结果表明：激光扫描速度保持恒定,激光功率增大,熔池的长度、宽度、深度均增大;激光功率保持恒定,扫描速度增大,熔池的长度变大,宽度和深度变小。最后获得了一组能够较好地满足成形需求,成形件不易产生翘曲和开裂的激光参数。     

工件预加载温度对Ti-6Al-4 V车削过程的影响

通过对比仿真和试验的切削力、切屑形态和锯齿化程度验证了仿真模型的可行性,然后用仿真分析的方法研究了工件预加载温度对切屑形貌、切削力和切削温度的影响,获得了锯齿形切屑转变为带状切屑的临界工件预加热温度。结果表明:随着预加载温度的增加,切屑变形减少;在v=50m/min时,锯齿形切屑转变为带状切屑的临界预加载温度为150℃～200℃;切削速度v=110～170m/min时,临界预加载温度为250℃左右。     

Ti-6Al-4V钛合金板与304L不锈钢网的扩散焊

分别在800℃、825℃、850℃焊接温度、30 m in保温时间,3 MPa焊接压力下,进行Ti-6A l-4V钛合金板与304L不锈钢网的真空扩散焊接。对接头组织结构与化学元素扩散进行了扫描电镜与能谱分析,并测试了接头的剪切强度。结果表明:不添加中间过渡层金属,可以成功地实现钛合金板与不锈钢网的扩散焊接,并使接头的剪切强度达到90 MPa以上。不锈钢网中的Fe、N、iCr扩散并固溶到钛合金中,稳定了β相,使钛合金在一定深度上,其组织由原来的α+β双相结构转变为单相的β相。不锈钢中的Cr,由于钛合金中Ti的扩散进入,而在界面发生了上坡扩散现象。这种Cr在不锈钢一定深度内的富集,形成窄长的富Cr区域,冷却后转变为硬脆的σ相。但在焊接接头中没有发现明显其它的金属间化合物或氧化物相的生成,使得接头的机械性能得到了很好的保证。     

Fretting fatigue of laser shock peened Ti-6Al-4V

The objective of this paper is to examine fretting fatigue of laser shock peened (LSP) titanium to quantify the influence of LSP on fretting fatigue life. Contact conditions such as loads and pad geometry are chosen to generate fretting fatigue stresses similar to those occurring in blade/disk contacts in gas turbine engines. LSP treated specimens attained 5-, 10- and 25-fold increase in lives compared to untreated specimens. Metallography of the contact area and fractographic analysis of worn pads detail the fretting behavior of LSP treated specimens.     

Fretting behavior of shot peened Ti-6Al-4V under slip controlled mode

Fretting tests of shot peened Ti-6Al-4V were conducted under slip controlled mode using a dual actuator test setup which could apply an independent pad displacement at a given applied bulk stress. Fretting regime was identified based on the hysteresis loop of tangential force versus relative slip range and the evolution of tangential force. Fretting regime changed from partial slip to mixed slip and then to gross slip with increasing relative slip range, and the transition from mixed to gross slip occurred at a relative slip range of ∼50 μm regardless of the applied bulk stress magnitude for both shot peened and unpeened specimens. Fretting fatigue life initially decreased as the relative slip range increased and reached to a minimum value, and then increased with an increase of the relative slip range due to the transition in fretting regime from mixed slip to gross slip. Shot peened specimens had longer fatigue life than unpeened specimens at a given relative slip range, but the minimum fatigue life was at the same value of the relative slip range for both shot peened and unpeened specimens. The relationship between relative slip and fatigue life was also found to be independent of the applied bulk stress level. Further, tangential force was directly related to relative slip and this relationship was independent of other fretting variables.     

钛合金TC4的钻削力试验研究

钛合金TCA属于较难加工材料,其小孔钻削尤为困难。为得到钻头直径、钻削参数（进给量、切削速度）和刀具材料对钻削力的影响规律,采用标准高速钢钻头对TCA与45钢进行了钻削对比试验,并用多元线性回归分析模型分别建立了扭矩和轴向力的经验公式。结果表明,TC4的钻削力比45钢大,钻削参数对钻削力的影响规律与45钢基本相同,即钻头直径对扭矩和轴向力影响最大,进给量次之,切削速度的影响最小。     

Fretting Wear Behavior of Laser Peened Ti-6Al-4V

This work deals with the influence of laser peening on the fretting wear behavior of Ti-6Al-4V. Laser peening was carried out on Ti-6Al-4V. The laser-peened surface was characterized by transmission electron microscopy. Surface roughness, nanoindentation hardness, residual stress, and tensile properties of the material in both laser-peened and unpeened conditions were determined. Fretting wear tests were conducted at different normal loads using a ball-on-flat contact geometry. Laser peening resulted in the formation of nanocrystallites on the surface and near-surface regions, increased hardness, and compressive residual stress. Laser peening did not affect the tensile properties and surface roughness significantly. There was no considerable difference between the values of the tangential force coefficient of laser-peened and unpeened samples. The fretting scar size, wear volume, and wear rate of laser-peened specimens were lower than those of unpeened samples. This may be attributed to an increase in surface hardness due to strain hardening and grain refinement at the surface and near-surface regions, higher compressive residual stress, and higher resistance to plastic deformation of laser-peened samples.