装备内孔零件的堆焊修复与滚压强化工艺研究

阐述了一种修复损伤内孔零件的精密脉冲等离子粉末堆焊+滚压强化复合处理工艺,通过试验对修复层的组织性能进行了观察与测试。结果表明:修复的薄壁内孔零件试样基体变形小,修复层与基体属于冶金结合,修复层和基体过渡区域(包括熔合区和热影响区)较窄,堆焊质量良好;堆焊修复内孔零件试样经车削+滚压强化处理后表面光滑、平整,粗糙度明显降低,且形成了高值残余压应力,这些都有利于改善修复零件的抗疲劳性能。该修理工艺简单可靠、经济实用,可实现损伤内孔零件控型与控性的有效结合,为重载装备的内孔零件修复提供了一种方法。     

药芯焊丝耐磨堆焊过程中FB树脂对碳化钨颗粒的热保护作用

为了减轻堆焊过程中碳化钨颗粒的熔化及溶解烧损,采用FB树脂作为热保护剂对铸造碳化钨颗粒进行了表面包覆处理,并对制作的药芯焊丝进行了TIG焊堆焊试验。用金相显微镜、扫描电镜和能谱仪对堆焊层的微观组织和碳化物形貌进行观察分析,结果表明:采用FB树脂保护的碳化钨颗粒在堆焊过程中的熔化及溶解烧损明显降低,堆焊后复合层中保留了大量的碳化钨颗粒,颗粒周围的碳元素含量较高。热绝缘剂的使用与否对基体显微硬度的影响较大,而对堆焊层表面的洛氏硬度影响较小。此外,还通过湿砂橡胶轮磨损台对药芯焊丝进行了磨损实验,结果表明:采用了热保护的堆焊层在磨损试验中能够有效地阻碍砂粒的犁削作用,从而使耐磨性大大增加。     

无电焊接中厚度钢板焊接接头的组织结构与性能研究

采用无电焊接方法对12mm厚度钢板进行了焊接。分析了满足中厚度钢板焊接能量要求的技术途径;利用SEM,EDS,XRD等手段观察、分析了焊缝的组织成分与显微结构;测试了焊接接头的拉伸强度、弯曲强度、显微硬度等力学性能。结果表明:在选择高放热体系基础上,通过增大焊接笔直径、减小反应物料粒径、提高压坯密度等方法,可以有效增大焊接热效率,从而满足中厚度钢板焊接能量需求;焊缝组织分为热影响区、熔合区与合金区,焊缝合金与母材间通过熔合区形成了冶金结合;焊接接头因固溶强化和析晶强化的作用,具有良好的力学性能,拉伸强度、平均显微硬度与弯曲强度分别为357MPa、186HV0.2与644MPa,达到了野战应急抢修技术要求。     

铝青铜水下湿法激光焊接焊缝成形与力学性能

为解决湿法焊接焊缝质量不高的问题,对铝青铜材料展开水下湿法激光焊接实验,利用扫描电子显微镜(Scanning Electron Microscope,SEM)、显微硬度仪、万能试验机分别检测和分析了焊接接头的微观组织和力学性能。结果表明:铝青铜水下湿法焊接会出现大量气孔,水深增加会导致气孔增多,提高焊接速度可以改善焊缝成形质量,通过在基体表面预置自蔓延粉末能够有效减少气孔;焊缝中上部为胞状晶组织,底部为发达的树枝晶;焊缝平均硬度为240 HV,与基体相比提高了50%;拉伸试验试件均断裂在焊缝处,平均拉伸强度为235 MPa,为基体的43%。     

一种Cu基自蔓延焊笔焊接Q235和45钢焊缝的组织与性能

利用研制的一种可焊接6～10 mm厚钢结构件的Cu基自蔓延焊笔,焊接了10 mm厚的Q235钢和45钢,研究了其焊缝的组织形貌和性能,发现焊缝与基体间存在熔合区,焊缝属于熔焊焊接.焊缝的拉伸强度达282 MPa,弯曲强度达628 MPa,冲击韧度为46.43 J/cm2;焊缝显微硬度达HV0.1230,熔合区显微硬度达HV0.1255.6,高于基体热影响区的硬度.     

扭力轴头的堆焊修复加激光强化

本文对某重载车辆扭力轴轴头的堆焊修复加激光强化工艺进行了试验研究.优选了激光强化的工艺参数;分析了堆焊及激光强化层的组织;并进行了硬度及接触疲劳试验.试验结果表明:堆焊加激光强化层的硬度高,其接触疲劳性能比原材料高频淬火略有提高;堆焊加激光强化修复扭力轴轴头具有较高的经济效益.     

铝合金-纯铝-钢复合板爆炸焊接试验及性能研究

通过设计爆炸焊接试验复合了铝合金-纯铝-钢爆炸复合板,对其界面形态、显微硬度及力学性能进行了研究。结果表明,铝合金-纯铝界面纯规则正弦波形,纯铝-钢复合板界面波形较小,铝合金-纯铝-钢复合板的界面剪切强度在75 MPa以上,爆炸复合过程中,纯铝与钢界面生成了金属间化合物,其界面处基体金属发生强烈的塑性变形。复合板变形及组织变化的结果造成复合板界面处的显微硬度最高,随着距界面距离的增加,两侧基体金属的硬度逐渐降低。     

喷丸强化对18Cr2Ni4WA渗碳钢性能的影响

采用强力喷丸工艺对渗碳18Cr2Ni4WA钢试样进行了表面喷丸强化处理。利用Nano Test 600纳米测试仪、2903X射线应力仪和TR200表面粗糙度仪，分别测试分析了试样处理前后的显微硬度、残余应力和表面粗糙度，并在JP-52接触疲劳试验机上考察了喷丸强化处理对渗碳18Cr2Ni4WA钢接触疲劳性能的影响。试验结果表明：渗碳试样经强力喷丸后，在0～0．50mm深的表层内形成一个喷丸硬化层，显微硬度提高了约1．1GPa；最大残余压应力由-478 MPa提高到-760 MPa；表面粗糙度由1．255μm降为0．979μm。接触疲劳特征寿命以与中值寿命L50均提高了2倍多，额定寿命L10提高了1倍多。     

环氧树脂/CTBN/无机颗粒高分子合金修补剂材料的制备与性能分析

通过端羧基丁腈液态橡胶(Carboxyl Terminated Butadiene Acrylonitrile,CTBN)协同纳米Al2O3、SiO2颗粒与微米MoS2颗粒共混改性环氧树脂,制备了双组分的耐磨高分子合金修补剂材料。采用拉伸、摩擦磨损等试验及SEM等方法测试和分析了该高分子合金修补剂的拉伸强度、显微硬度等基本性能及摩擦学性能,并对其耐磨减摩机理进行了分析。结果表明:该材料的拉伸强度为42.3MPa,拉伸剪切强度为13.8MPa,显微硬度为231.1MPa,摩擦因数为0.17,耐磨性比LY12铝合金提高了50%。     

45钢表面激光熔覆ND35合金涂层的组织及性能

为了修复45钢磨损装备零件,采用激光熔覆工艺在45钢表面制备了Ni35合金涂层.利用扫描电镜(SEM)、能谱分析仪(EDS)、X射线衍射仪、显微硬度计和磨损试验机分析了熔覆层的显微组织,测试了涂层的硬度和耐磨性能.结果表明:熔覆层由γ-Ni和Ni3B两相组成;熔覆层中存在平面晶、胞状晶、枝晶等多种形态;Ni35熔覆层的硬度为450 HV,熔覆层的耐磨性是基体的2.86倍.     

自行火炮扭力轴载荷谱的测量及疲劳寿命预测

为预测自行火炮扭力轴寿命，对某型自行火炮在不同工况下进行实车试验，获得了多工况下扭力轴的载荷谱。受力分析表明，表面最大拉应力是扭力轴的破坏应力；提出基于随机响应面对扭力轴寿命进行预测的方法，将低周疲劳寿命表达式中的随机参数表示为标准随机变量，引人随机响应的Hermite多项展开式进行拟合，建立了扭力轴疲劳寿命的显式函数。通过对实测载荷谱进行统计分析，依据寿命表达式可以预测扭力轴疲劳寿命，并给出概率分布。该方法弥补了传统响应面法以一般多项式拟合时不能保证收敛性的缺陷。     

Effect of post weld heat treatment on tensile properties and microstructure characteristics of friction stir welded armour grade AA7075-T651 aluminium alloy

This paper reports the effects of post weld heat treatments, namely artificial ageing and solution treatment followed by artificial ageing, on microstructure and mechanical properties of 12 mm thick friction stir welded joints of precipitation hardenable high strength armour grade AA7075-T651 aluminium alloy. The tensile properties, such as yield strength, tensile strength, elongation and notch tensile strength, are evaluated and correlated with the microhardness and microstructural features. The scanning electron microscope is used to characterie the fracture surfaces. The solution treatment followed by ageing heat treatment cycle is found to be marginally beneficial in improving the tensile properties of friction stir welds of AA7075-T651 aluminium alloy.     

2A12铝合金焊接接头超声冲击处理前后拉伸性能分析

为克服铝合金薄板焊接接头强度偏低、韧性不足的缺点,用ER5356焊丝对不同厚度的2A12铝合金板材进行了手工氩弧焊接,并采用超声冲击处理对焊接接头进行全覆盖强化处理。采用金相显微镜观察了处理和未处理焊接接头的显微组织结构,对接头的力学性能进行了测试分析,分析了超声冲击处理改善2A12铝合金焊接接头力学性能的机理。结果表明：铝合金焊接接头经超声冲击强化处理后,6 mm和4 mm厚板材对接接头的抗拉强度分别提高了17.4%和23.7%,延伸率分别提高了28%和44%,焊缝表层组织得到明显细化。分析认为：晶粒大幅细化、组织致密化和缺陷减少,是超声冲击处理改善铝合金焊接接头抗拉伸性能的主要原因。     

Friction welding of AA6061 to AISI 4340 using silver interlayer

The present work pertains to the study on joining of AA6061 and AISI 4340 through continuous drive friction welding. The welds were evaluated by metallographic examination, X-ray diffraction, electron probe microanalysis, tensile test and microhardness. The study reveals that the presence of an intermetallic compound layer at the bonded interface exhibits poor tensile strength and elongation. Mg in AA6061 near to the interface is found to be favourable for the formation and growth of Fe2Al5 intermetallics. Introduction of silver as an interlayer through electroplating on AISI 4340 resulted in accumulation of Si at weld interface, replacing Mg at AA6061 side, thereby reducing the width of intermetallic compound layer and correspondingly increasing the tensile strength. Presence of silver at the interface results in partial replacement of Fe-Al based intermetallic compounds with Ag-Al based compounds. The presence of these intermetallics was confirmed by X-ray diffraction technique. Since Ag-Al phases are ductile in nature, tensile strength is not deteriorated and the silicon segregation at weld interface on AA6061 in the joints with silver interlayer acts as diffusion barrier for Fe and further avoids formation of Fe-Al based intermetallics. A maximum tensile strength of 240 MPa along with 4.9% elongation was obtained for the silver interlayer dissimilar metal welds. The observed trends in tensile properties and hardness were explained in relation to the microstructure.     

光波导微模具飞切加工工艺

针对目前模压制作工艺中高精度的光波导微模具加工工艺比较复杂的问题,基于金刚石超精密机械加工技术在光学元件微结构的广泛应用提出了光波导微模具的金刚石飞切高效快速的加工方法.通过超精密飞切加工系统以硬铝为模具材料进行了工艺优化的正交试验.试验结果表明:背吃刀量对光波导微结构表面质量的影响相当敏感,主轴转速对微结构表面质量的...     

Multifunctional A356 alloy/ PKSAnp composites: Microstructure and mechanical properties

Mechanical properties and microstructure of multifunctional composites produced with palm kernel shell ash nanoparticle (PKSAnp)-A356 alloy composites was studied. The composites were produced using Double layer feeding stir casting method (DLF-SCM) by adding 1 wt%‒4 wt.% PKSAnp. The microstructure, density, electrical and mechanical properties were determined. The results shows that there was a uniform distribution of the PKSAnp in A356 alloy. The mismatch at the interface between the PKSAnp and A356 alloy was 4.26%. Improvement of 30.47%, 41.91%, 49.52%, 40.90% and 65.09% were obtained for hardness values, tensile, yield strength, %elongation and impact energy at 4 wt% PKASnp. The work has established that the developed composites can be used for multifunctional applications where combination of toughness and strength is vital.     

Optimization of process parameters of aluminum alloy AA 2014-T6 friction stir welds by response surface methodology

The heat treatable aluminum-copper alloy AA2014 finds wide application in the aerospace and defence industry due to its high strength-toweight ratio and good ductility. Friction stir welding(FSW) process, an emerging solid state joining process, is suitable for joining this alloy compared to fusion welding processes. This work presents the formulation of a mathematical model with process parameters and tool geometry to predict the responses of friction stir welds of AA 2014-T6 aluminum alloy, viz yield strength, tensile strength and ductility. The most influential process parameters considered are spindle speed, welding speed, tilt angle and tool pin profile. A four-factor, five-level central composite design was used and a response surface methodology(RSM) was employed to develop the regression models to predict the responses.The mechanical properties, such as yield strength(YS), ultimate tensile strength(UTS) and percentage elongation(%El), are considered as responses. Method of analysis of variance was used to determine the important process parameters that affect the responses. Validation trials were carried out to validate these results. These results indicate that the friction stir welds of AA 2014-T6 aluminum alloy welded with hexagonal tool pin profile have the highest tensile strength and elongation, whereas the joints fabricated with conical tool pin profile have the lowest tensile strength and elongation.     

磺化酚醛树脂的研究:高效减水剂的制备及其对混凝土工作度和力学性能的影响

制备了以磺化酚醛树脂为基础的3种高效减水剂,该高效减水剂能显著地减少用水量和改善混凝土工作度以及力学强度.测试结果显示:随掺量的增加,混凝土抗压强度在一定范围内有明显的提高,然后增加较慢或有所下降;混凝土的抗折、抗拉、抗剪强度以及与钢筋的粘接强度均高于对照空白样.同硅灰、磨砂矿渣相结合还获得了抗压强度大于100MPa、流动性好的超高强混凝土.     

高速微粒轰击45钢表面纳米化过程中铁素体相晶粒细化过程分析

利用高速微粒轰击技术在45钢表面制备了纳米晶,利用透射电镜（TEM）和X射线衍射（XRD）等分析技术对距表面不同深度的微观结构进行分析,研究铁素体相晶粒细化过程。结果显示：随着距表面距离的减小结构尺寸逐渐减小,在最表面形成了纳米晶层,平均晶粒尺寸约为15 nm。通过不同尺寸位错胞的逐步形成,以及位错墙不断向晶界演化,晶粒被细化为细小的纳米晶。     

火药复合焊条焊接接头的微观组织及性能

为提高战场装备的应急抢修能力,以火药和2Al/3CuO系高热剂为焊接热源,开发了一种新型的便携式焊接材料——火药复合焊条,对其焊缝的组织形貌及性能进行研究.试验结果表明,火药复合焊条的焊接属于熔化焊,焊缝与基体之间存在明显的过渡区,焊缝成形良好,焊缝的抗拉强度大于400MPa,高于母材本身强度,能够满足战场应急抢修能力的需要.