机场跑道异物(Foreign Object Debris,FOD)探测系统易折杆设计是保证探测系统有效工作的关键,对防范FOD引起的机场安全风险具有至关重要的作用.文中以FOD探测系统支架易折杆为研究对象,提出在圆管上开半圆形缺口的设计方案以实现易折杆易断和耐疲劳的综合力学性能.通过有限元模拟方法,分析了不同圆角半径、圆管壁厚和缺口形状的易折杆在不同工作载荷下的应力应变状态.结果表明,随着缺口半径增大或壁厚减小,缺口根部应力水平提高,能够使易折杆在受到飞机撞击时快速断开,具备易折特性,但会降低疲劳寿命;反之会增加疲劳寿命,但不容易实现易折特性.合理调节壁厚和圆角半径,可以使易折杆具有易断性和耐疲劳的综合力学性能.

This study investigates the microstructural inhomogeneity in the bonding zone of AISI 410S/A283GrD explosive-welded plate by experiment and simulation. The interfacial microstructure and chemical components are investigated, and the difference of grain size across the peak and valley is studied separately. Due to severe plastic deformation and work hardening during the explosive welding process, the microhardness of the combination area adjacent to the interface is higher than that of parent plates. The wavy interface of the numerical simulation is in good agreement with the experimental observation. The numerical simulation results, such as distribution of shear stress, pressure, and effective plastic strain rate of the model are investigated, and the forming reason of interfacial microstructures, are explained by these results.

文章构建了原子扩散计算模型用于摩擦焊条件下金属基体原子扩散系数的数值计算,以铝/镁异质金属回填式搅拌摩擦点焊(FSpW)连接为例,从理论上分析了动态再结晶过程中的原子扩散机制,定量评价了形变诱导的过饱和空位增强扩散效应和位错管道扩散效应.探索了快速扩散通道(晶界、位错、空位)对原子扩散的影响,结合焊点热变形计算,建立了原子扩散与热变形之间的定量关系,从而明确了Al/Mg异质金属搅拌摩擦焊过程原子热-力耦合超扩散机制.在FSpW界面Al原子和Mg原子扩散层厚度测量的基础上,基于Fick定律反推获得界面处原子扩散系数.经过对比发现,采用原子扩散系数模型计算结果与根据扩散层获得界面原子扩散系数拥有相同数量级.

采用冷金属过渡(Cold metal transfer,CMT)焊接技术在Q345钢表面堆焊高Cr合金钢,以期对Q345进行表面强化.结果 表明,CMT焊接技术在Q345钢表面堆焊高Cr合金钢方法可行,并且焊缝结合良好,无明显裂纹.组织主要是铁素体和珠光体,堆焊组织以马氏体和残余奥氏体为主.CMT焊接热输入低、热影响区小、界面处基体稀释率低.堆焊层硬度平均值为490 HV0.2,基体组织硬度平均值为182 HV0.2,复合板的冲击吸收能量为35J.主要的断口形貌为撕裂棱和解理,基体和堆焊层的界面发现裂纹分叉.

目的 探究C276/304L异种金属爆炸焊接过程中温度变化历程与界面微观组织形成的关系.方法 利用爆炸焊接工艺获得结合良好的复合板,观察测量复合界面的微观组织和显微硬度分布.运用ANSYS/AUTODYN数值模拟对界面形成过程进行分析,探究界面温度场变化与熔化区组织形成的内在联系.结果 对比模拟结果发现,界面在复合过程中存在高应变率及严重塑性变形而经历快速升温,界面升温速率可达2.35×109℃/s,这将导致局部区域材料发生熔化和混合,并在旋转作用下形成漩涡;而后经历快速冷却过程,冷却速率可达107～109℃/s,形成独特的熔化区组织.高温高压及高塑性变形导致熔化层产生的同时,对界面附近硬度也会产生影响.结论 熔化区组织的形成与复合过程中的高升温速率及冷却速率有关,同时界面因剧烈变形产生应变硬化.

采用LWS-1000型Nd:YAG激光器在1050铝合金表面多层激光熔覆制备Al-70Si,观察和测试分析了Al-70Si的宏微观组织和相关力学性能,并探究了热处理对熔覆层的影响.结果表明:脉冲激光加工技术可以成功制备Al-70Si材料,熔覆层中硅颗粒自基体侧起分别呈现圆润球状、长条状、五星瓣状,熔覆层平均硬度值达到250 HV,抗拉强度为85 MPa,基体耐磨性能明显提高.进行500℃保温4 h热处理后,硅颗粒尺寸降低且尖角钝化,更为圆润,硬度值上升50 HV,热导率也相应提高.

Abstract Tungsten/steel joints are desired for fusion reactors and militarily applications, as it could combine the unique properties of these two dissimilar metals. In view of the large differences of physical and chemical properties between W and steel, diffusion bonding is considered to be the proper technique for joining of W to steel. In this paper, diffusion bonding of W to low activation ferritic/martensitic steel at 1050 °C with 50 MPa for 20 min by spark plasma sintering (SPS) were investigated. The results showed that direct diffusion bonding of W to steel was feasible. However, the formation of ferrite and carbide at the W/steel interface lowered the joint strength. Effects of the insertion of ductile interlayers (Nb, Nb/Ni) on the joining interface microstructure and mechanical properties of W/steel joints were studied. The detailed microstructural characterization revealed that Nb could prevent the formation of ferrite and carbide at the W/steel interface. The Ni promoted the interfacial diffusion between Nb and steel. The shear strength and Vickers hardness of the joints were evaluated.

In this study, oxide dispersion strengthened (ODS) layers with different Y2O3 addition were cladded on China Low Activation Martensitic (CLAM) steel to improve its mechanical strength, micro-hardness and high-temperature behavior. The results show that fine surface morphologies can be observed in cladding zones. In cladding layers, the Fe, Cr, W, Y, Ti elements was discriminated by the scanning electron microscope (SEM) with energy-dispersive spectrometer (EDS) and the most stable Y-Ti oxide complexes Y2Ti2O7 phase were analyzed by X-ray diffraction (XRD). The micro-hardness of ODS layers are higher than that of CLAM steel. The CLAM steel with 2 wt% Y2O3 addition ODS layer possesses an average tensile strength of 840 MPa which is 166 MPa higher than that of CLAM steel. It is suggested that the dispersion strengthening of oxide particles in ODS layer contributed to the increased strength.

24Ti-76Si (wt.%) eutectic alloy as a novel sintering aid for hot-pressing of B4C-based ceramic composites was proposed in this paper. B4C-TiB2-SiC ternary ceramic composites were fabricated by hot-pressing at 1850 degrees C via in-situ reaction of B4C and Ti-Si eutectic alloy. The results indicated that the addition of Ti-Si eutectic alloy significantly increase the density and enhanced the mechanical properties of B4C-based composites. The Vickers hardness, flexural strength, fracture toughness and compressive strength were 28.4 +/- 1.1 GPa, 582.3 +/- 45.5 MPa, 6.3 +/- 0.4 MPa m(1/2), and 4109.3 +/- 209.6 MPa, respectively, for the composite prepared with B4C-30 wt.% Ti-Si. These values were much higher than those of nominally pure B4C ceramic prepared by the same processing condition. The improved mechanical properties were attributed to the well-dispersed fine intergranular/intragranular TiB2 and SiC phases in the B4C matrix.

为消除FeCrNiAlBSi电弧喷涂层的缺陷,对Q235钢表面的FeCrNiAlBSi电弧喷涂层进行激光重熔处理.采用现代分析技术测试了FeCrNiAlBSi电弧喷涂层激光重熔前后的金相组织、硬度和耐磨性能.结果表明:激光重熔降低了FeCrNiAlBSi电弧喷涂层的孔隙率,使其组织致密,改善了其综合性能.FeCrNiAlBSi电弧喷涂层的截面组织呈层状结构,内部存在金属结晶相、金属氧化物及少量孔隙,显微硬度均值为558.4 HV1N;激光重熔后原喷涂层中的孔隙大量消除,层状组织消失,与基体及各涂层之间均为冶金结合,显微硬度达到1 020.8 HV1N;FeCrNiAlBSi电弧喷涂层重熔后的磨损失重约为重熔前的2/3,与电弧喷涂层相比激光重熔后的磨损刮痕宽度最窄,深度最小.

Joining of SiC ceramic with Ag-Cu-Ti active alloy reinforced with Cr3C2 particulates to control the microstructure and increase joint strength was investigated. The results indicated that the reaction of titanium in the brazing alloys and Cr3C2 particulates was detected, but it would not affect the reaction of Ti and SiC. TiC reaction layer with a thickness about 100 nm was formed at the interface between SiC ceramic substrate and brazing alloy. Ti5Si3 silicide phases were also observed near the reaction layer. The Cr3C2 particulates randomly distributed in the braze matrix (< 10 vol% Cr3C2) and refined the Ag-rich and Cu-rich solid solution phase. Cu2Ti intermetallic phase was also found in the joint. The clustering and particle-to-particle contact behavior of Cr3C2 particulates was observed in the joint with high amount of Cr3C2. The joint strength increased with increasing the volume fraction of added Cr3C2 particulates first and then decreased. The shear strength of the joint brazed with 10 vol% Cr3C2 addition reach up to 212.8 MPa, which was 134.2 MPa higher than that brazed with Ag-CuTi brazing alloy.

向一种新型Fe-CrC系堆焊粉芯中分别添加不同含量硼、钒元素,并在氮气作为主要保护气的条件下在Q235基体上制备熔敷层.用金相显微镜对熔敷层组织进行了观察,测定熔敷后试样的显微硬度并进行了分析.结果表明,熔敷层中析出硬质氮化物,添加硼元素后析出一定量硬质相导致熔敷层硬度进一步增加,随着硼元素含量增加,硬质相数量增加并逐渐聚集;加入钒元素后,析出相更加细小且分布均匀,随着钒元素含量增加析出相数量变化不大,熔敷组织硬度提升不明显.

采用Q235钢作为基体材料,采用合适的高速电弧喷涂工艺参数在基体表面制备FeCrNiAlBSi涂层.之后对FeCrNiAlBSi涂层在一定参数下进行激光重熔处理,对比FeCrNiAlBSi涂层及其激光重熔层的金相组织、组织性能和抗高温氧化性能.结果表明,在喷涂电压32～34V,电流200～220A的条件下制备FeCrNiAlBSi涂层,截面组织呈层状结构,主要由Fe-Cr金属结晶相、金属氧化物及少量孔隙组成,显微硬度和结合强度均值分别为558.4HV0.1、17.2MPa.在功率280W、离焦量-0.5mm,扫描速度180 mm/min、搭接率70％的参数下进行激光重熔,重熔后涂层主要由Ni-Cr-Fe、Fe-Cr组成.孔隙大量消除,层状组织消失,涂层与基体之间以及叠层之间由机械结合转变为冶金结合.重熔后在600℃×48h实验条件下,FeCrNiAlBSi涂层的氧化增重约为基体的1/3,激光重熔层的氧化增重仅为基体的1/6.

FePCrC coating was prepared by high velocity arc spraying machine with phosphorus-containing metal cored wire.The microstructure of the coating was analyzed.The results show that the coating has a typical lamellar structure with a lower porosity of 3.92％ and a higher density,and the main phases in the coating are Fe-Cr,Cr7C3 and FePO4.In addition,the microscopic heterogeneity coefficient KCMH was introduced to analyze the microscopic inhomogeneity of the chemical composition of the coating.And the KCMH was calculated to be 0.021 7,which indicates that the coating is uniform.

针对传统的铸造渣包存在易开裂、使用寿命短等问题,提出了一种焊接式渣包设计方法.首先根据产品性能与功能需求,对渣包进行结构设计,然后通过渣包设计参数进行模型壁厚计算,最后在不影响渣包整体分析结果,对产品模型简化处理,运用有限元模拟分析渣包在静力载荷与热应力作用下的应力、应变.结果表明,所设计的渣包强度、硬度符合实际技术需求,渣包应用实际工程效果良好.

利用高速电弧喷涂技术制备大面积Fe-Cr-P-C涂层,分析涂层组织和成分的不均匀性,并探究其对涂层显微硬度不均匀性的影响.结果表明,涂层为典型的层状结构,且呈薄片形,涂层的孑L隙率仅为3.27％,雾化粒子间不同的热-动力学条件导致涂层的组织结构及析出相分布存在不均匀性.喷涂过程中气孔的存在及微量相的硬化作用是导致涂层硬度不均匀的主要原因.引入微观不均匀系数kmh来衡量涂层化学成分的不均匀性,在实验范围内,涂层平均Kmh约为0.054,表明涂层的化学成分比较均匀,为均质涂层,涂层此时具有最佳的显微硬度.

利用自设的新型粉芯丝材,通过高速电弧喷涂技术制备了FeCrBAlNiSi非晶涂层,针对涂层的组织结构和性能进行了深入研究.结果表明,涂层组织致密,其层状结构呈薄片形,涂层孔隙率为5.6％.涂层含有29％的非晶相,且主要存在于近基体涂层中,而晶体相则主要为Fe-Cr相、AlNi3相、CrB相、Ni4B3相和Al2O3相.非晶相的存在及因沉积效果产生的缺陷决定了涂层的显微硬度的不均匀性,涂层平均硬度接近800 HV0.1,最大可达1 115.3 HV0.1,属于硬质涂层.涂层的晶化温度约为712℃,较其他几种非晶涂层涂层有更好的热稳定性.

In this article,it adopted gas metal arc welding(GMAW) and submerged-arc welding method to conduct weldability test on X80M pipeline steel,and then the mechanical property test and microstructure observation for welded joint were carried out and SEM scanning for impact fracture area. The results showed that the mechanical properties meet the requirements of relevant standards,and microstructure accord with characteristics of pipe body and weld. The thick columnar crystal structure resulted in lower toughness,so it should properly control welding heat input.

As a gap-atom element,nitrogen can improve many properties of steels through reactions with other alloy elements,including hardness,toughness,wearing resistance and pitting resistance.Using the nitrogen instead of the carbon,the welding hot crack resistance,wearing resistance and high temperature stability of deposited metal can be greatly improved.Based on the theoretical study and applications,the research status of nitrogen-alloying surfacing materials was introduced in detail in this paper.The dissolution and precipitation of nitrogen in steel,carbonitride precipitation and its strengthening mechanism was presented with emphasis.The development of nitrogen-alloying surfacing materials' application was also summarized through some examples.

Taking TIG ＋ high-purity argon as protective gas welding method to link the zirconium R60702 plate at different protection temperatures, and using electrochemical corrosion and the morphology observation of optical microscope, R60702 corrosion behavior in acetic acid was studied. The results showed that in 5 mol/I, acetic acid solution, the dominated corrosion type of welded joints was pitting corrosion. The corrosion resistance of zirconium R60702 seriously declined when the protection temperature was at 800℃, and when the protection temperature was at 315℃ and 400℃, its corrosion resistance had no obvious decline compared with the welding state under strict protection.