电弧超声对SiC_p/6061Al复合材料等离子弧焊缝组织与接头性能的改善作用

通过高频调制等离子电弧激发出电弧超声,以Ti-6061Al合金片作为填充材料对SiC_p/6061Al复合材料进行等离子弧(PAW)原位合金化焊接,并与常规PAW进行对比,研究了电弧超声对焊缝组织和性能的影响。结果表明:与常规PAW相比,电弧超声使焊缝组织明显细化,TiN、TiC等颗粒分布更加弥散,且无气孔、裂纹等缺陷,焊缝中没有发现脆性相Al_4C_3的生成;电弧超声使焊缝中心区硬度有一定程度下降;焊接接头抗拉强度提高到252 MPa,比常规PAW焊接接头的提高了约7%;同时拉伸断口韧窝数量明显增加,呈现出明显的韧性断裂特征。     

填加焊丝对碳化硅颗粒增强铝基复合材料钨极惰性气体保护焊焊缝成形及组织的影响

采用钨极惰性气体保护焊工艺,对不填加焊丝与填加铝硅焊丝条件下SiCp/6061Al复合材料的焊接性进行了研究.结果表明:不填加焊丝时,焊缝外观成型较差;而填加焊丝后,熔池流动性增强,可以得到满意的鱼鳞纹焊缝,并有效抑制了焊缝中的SiCp颗粒和铝的界面反应,焊缝中的缺陷减少,接头性能得到改善.     

铝-钛-镍-硅合金填料对SiC_p/6061Al基复合材料等离子弧焊接接头组织与性能的影响

以铝-钛-镍-硅合金为填充材料,采用氩/氮混合等离子气体对SiCp/6061Al基复合材料进行等离子弧原位焊接,研究了不同成分合金填料对焊接接头组织与性能的影响。结果表明:填充Al-10Ti-10Ni-3Si合金的焊缝组织均匀、致密,存在少量50μm长的针状相,熔合区Al3Ti相数量较中心区的减少,无灰色针状Al4C3相;填充Al-5Ti-5Ni-5Si合金的焊缝中增强相数量较前者的有所减少,并呈无序分布,同样也无针状相;焊缝由Al N、Al3Ti、TiC、Ni3Al、Ni Ti2、Ti5Si3等相组成;两种接头的抗拉强度分别为215.0 MPa和221.5 MPa。     

钛基复合材料TIG焊接接头的显微组织和拉伸性能

采用非熔化极惰性气体钨极保护(TIG)焊技术对非连续增强钛基复合材料进行焊接,研究了焊接接头的显微组织与拉伸性能。结果表明:TIG焊接可较好地实现钛基复合材料的连接,焊缝成形良好,表面均匀洁净,未见微裂纹、气孔等焊接缺陷;接头由焊缝区、热影响区和母材区组成;接头中焊缝区和靠近焊缝的热影响区中β相晶界上分布的增强体TiB具有较高的长径比,细化程度较高,同时焊缝区和靠近焊缝的热影响区中存在大量针状马氏体α′相;接头的抗拉强度为1 137MPa,为母材的92%,断后伸长率为2.20%;接头拉伸时均在母材区断裂,拉伸断口主要呈韧性断裂特征,部分区域呈沿晶断裂特征。     

钛合金电弧超声TIG焊研究

进行了TC4电弧超声TIG焊接与传统TIG焊,利用X射线探伤检测接头质量,金相显微镜和SEM观察接头组织和断口,利用万能实验机测试接头拉伸性能.结果表明,严格按照航空标准进行TC4常规TIG焊与电弧超声TIG焊,所获得的接头均达到航空一级；随着加入超声频率的增加,激励电压的增大,电弧超声TIG焊焊缝组织细化、等轴化,枝晶破坏痕迹不明显,接头拉伸强度、屈服强度和延伸率均有所提高.     

含Sc高强铝合金薄板TIG焊与FSW接头组织与性能对比研究

分别对3mm厚的Al-Zn-Mg-Cu-Sc高强铝合金薄板进行钨极惰性气体保护(Tungsteninertgas,TIG)焊与搅拌摩擦焊接(Friction stir welding,FSW),对比分析了两种焊接工艺下接头的微观组织与力学性能。结果表明:两种工艺都能获得无缺陷的接头。TIG焊核区晶粒粗大;硬度分布呈"M"形,中心值降至125HV,最低值出现在热影响区(Heat-affected zone,HAZ)(约110HV);拉伸时样品断在HAZ,接头强度约为417MPa,为母材的71%。FSW焊核区为等轴细晶;硬度分布呈典型"W"型,最低值亦出现在HAZ(约115HV),且随焊速的提高而提高;在400～1 200r/min下均有可能获得高强度接头,其中转速1 200r/min、焊速200mm/min下接头强度最高(458MPa),为母材的79%,拉伸样品断在HAZ。当焊速过快时,由于合金变形能力差,焊核区易出现缺陷,导致拉伸时接头过早断裂于焊核区中心。     

6061-T6铝合金超声辅助搅拌摩擦焊接头的组织与力学性能

对3mm厚6061-T6铝合金板进行超声辅助搅拌摩擦焊(UA-FSW),研究了UA-FSW接头的焊接质量、力学性能、拉伸断口形貌以及焊核区的组织,并与FSW接头的进行了对比。结果表明:UA-FSW能有效减少焊接缺陷,拓宽焊接工艺窗口;两种接头的显微硬度曲线均呈"W"形,焊核区均呈"洋葱环"特征,但UA-FSW接头焊核区的"洋葱环"更为流畅;与FSW接头相比,UA-FSW接头的硬度和拉伸性能更高,断口上的韧窝更多、更深,焊核区的晶粒更小、更均匀。     

西气东输二线工程X80钢管半自动焊工艺研究

以西气东输二线工程用X80钢管为研究对象,通过焊接接头横向拉伸试验,焊缝和热影响区（HAZ）冲击韧性试验,焊缝和HAZ不同焊层显微组织分析,以及焊接接头不同焊层Hv10硬度试验等手段,研究了低氢型焊条根焊和自保护药芯焊丝半自动填充、盖面组合焊接工艺的环焊缝的焊接接头性能。试验结果表明,选择韧脆转变温度较低的自保护药芯焊丝、采用较小的焊接热输入量和多层多道的焊接措施等因素,对于保证X80钢管环焊接头的性能是至关重要的。采用低氢焊条根焊、自保护药芯焊丝半自动焊进行X80钢管焊接时,焊接接头的强度、-10℃低温冲击韧性和硬度等性能良好．该工萝应用于西气东输二线工程的焊接旆工是可行的．     

电流与保护气体对Q235A与304不锈钢异种TIG焊接接头的影响

采用TIG焊接工艺,选用直径为Ф2.0 mm的ER309焊丝对304不锈钢和Q235A进行对接双面焊,改变焊接电流大小及保护气体流量,通过对焊接接头拉伸实验、SEM断口及能谱分析,发现焊接电流取110 A,气体流量取6 L/min时,焊缝组织均匀,其力学性能较好,形貌出现明显韧窝。     

基于铝合金材质的液压元件焊接工艺探讨

液压元器件中大多采用碳钢材料进行制造,不仅重量大而且耐蚀性较差,影响了主机性能和寿命。采用6061-T6铝合金替代原有碳钢材料制造液压元器件,不仅实现了主机重量轻而且耐蚀性指标有大幅度提升。然而这种铝合金焊接部位容易出现软化现象,该文探究了不同焊丝对6061-T6铝合金TIG焊焊接接头性能的影响。     

Effect of welding processes on tensile properties of AA6061 aluminium alloy joints

The present investigation is aimed at to study the effect of welding processes such as GTAW, GMAW and FSW on mechanical properties of AA6061 aluminium alloy. The preferred welding processes of these alloys are frequently gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) due to their comparatively easier applicability and better economy. In this alloy, the weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties and poor resistance to hot cracking. Friction stir welding (FSW) is a solid phase welding technique developed primarily for welding metals and alloys that heretofore had been difficult to weld using more traditional fusion techniques. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass butt welded joints. The filler metal used for joining the plates is AA4043 (Al-5Si (wt%)) grade aluminium alloy. In the present work, tensile properties, micro hardness, microstructure and fracture surface morphology of the GMAW, GTAW and FSW joints have been evaluated, and the results are compared. From this investigation, it is found that FSW joints of AA6061 aluminium alloy showed superior mechanical properties compared with GTAW and GMAW joints, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone.     

Advancement and characterization of Al-Mg-Si alloy using reinforcing materials of Fe2O3 and B4C composite produced by stir casting method

The modifications of Al6061-T6 metal matrix composites is an extraordinary enthusiasm of recent pertinence for lesser weight materials with high value of tensile strength, hardness and wear protection, which can be widely used in automotive and aircraft design. In this paper, we investigate the impacts of the reinforced Al6061 composite with 5 wt% of Fe₂O₃ in addition to 2 %, 4 %, 6 % weight of B₄C being made-up by stir casting technique. In this research, Al6061 composites have analyzed by its physical and mechanical properties like as density, hardness, impact strength, ultimate tensile and compressive strength, and an optical microscope is utilized to assess the metallurgical properties such as microstructure with different wt% of reinforcement of Al6061 composite. The microstructure of newly prepared composites was shown a regular spreading of reinforcements in the matrix by an optical microscope and also the muscular bonding between the matrix and reinforcements were demonstrated by SEM analysis. It is further identifying that, microstructure uniformity and therefore the tensile strength of the metal composites was enhanced with increasing the fraction of Fe₂O₃ and B₄C particles without any decrement in elongation.

     

Characterization of ZrC reinforced AA6061 alloy composites produced using stir casting process

In the present study, effect of ZrC vol.% on mechanical properties of AA6061 metal matrix composites (MMCs) produced via stir casting technique was investigated. The vol.% of ZrC particles was varied as 5,10 and 15. The composites were characterized for its microstructure and mechanical properties and their relationships were obtained. The scanning electron microscope (SEM) images revealed uniform distribution and good bonding between the AA6061 alloy and the ZrC particles. The mechanical properties of the AA6061 alloy was found to significantly improve with the addition of ZrC particles from 5 to 15 vol.%, the hardness increased from 32 to 68 HV, yield strength increased from 50 to 86 MPa and the ultimate tensile strength increased from 118 to 165 MPa. However, the % of elongation of the composite samples decreased with 15 vol.% addition of ZrC particles. Sliding wear behaviour of the composites was investigated using a pin-on-disc wear tester at a load of 9.8 N and addition of ZrC particles was significantly found to reduce the wear rate of AA6061 alloy.

     

合金诱发反应脉冲TIG焊接铝基复合材料

探讨了SiCp/Al复合材料脉冲氩弧焊过程中合金元素Ti发生诱发反应的可行性。结果表明,焊接时,Ti的加入有利于避免SiC/Al之间发生界面反应;接头拉伸实验、显微硬度测试和金相组织观察表明,接头性能良好;X射线衍射相结构分析显示,接头焊缝金属中大致含有Al, TiC, Si, Ti, SiC等组成相。文中对Ti元素发生诱发反应的机理,以及对提高接头性能的作用进行了讨论。     

固溶处理对7B04-O铝合金搅拌摩擦焊接接头微观组织与力学性能的影响

对航空用3 mm厚的带有包铝层的7B04-O铝合金板材进行搅拌摩擦焊接(Friction stir welding,FSW),研究固溶处理对搅拌摩擦焊接接头的微观组织和力学性能的影响。结果表明,当转速为800 r/min、焊接速度为200 mm/min、焊接工具轴肩直径为12 mm时,可得到表面美观、致密无缺陷的搅拌摩擦焊接接头。焊核区发生动态再结晶,形成细小的等轴晶。经固溶处理后,焊核的上部及底部晶粒都发生了异常长大,而中部区域晶粒仍然为细小的等轴晶组织。焊态接头的拉伸试样断裂在母材位置,抗拉强度达到199 MPa,与退火态母材抗拉强度相当,断后伸长率达到12%。在新淬火状态下,接头的抗拉强度为310 MPa,为相同热处理母材的91.4%,断后伸长率为11.2%,试样断裂在焊核区,呈不完全的韧性断裂。     

Effects of Morphological Characteristics of Alumina Particles and Interfacial Bonding Strength on Wear Behavior of Nano/Micro-alumina Particulates Reinforced Al/A206 Matrix Composites

Matrix/reinforcement interface has a critical role in determining the properties of metal matrix composites (MMCs). Properties of matrix/reinforcement interface depend on the fabrication method. The main problem in the fabrication of MMCs is wettability between reinforcing particles and molten alloy. Al206/5 vol% alumina_p cast composites were fabricated by the addition of reinforcing particles into molten Al alloy, semi-solid and liquid states, in two different forms: (1) as-received alumina (nano/micro) particles and (2) pre-synthesized composite reinforcement prepared via ball milling of alumina (nano/micro) with Al and Mg powders (master metal matrix composite). The effects of powder addition techniques, alumina/matrix interfacial bonding strength, and morphological characteristics of alumina particles on wear behavior were investigated. A new combination parameter, called alumina particle appearance (APA) index, was introduced. APA index approximates the collective effects of morphological characteristics of alumina particles on wear behavior. It is suggested that samples with lower APA index have superior wear properties. Microscopic examinations of the composite and matrix alloy and alumina/matrix interface were studied by scanning electron microscopy and transmission electron microscopy. It was found that wear resistance was increased in the composites fabricated by the addition of pre-synthesized reinforcing particles into molten alloy in the semi-solid state. Improvement in wear resistance is attributed to higher bonding strength of matrix/reinforcement as well lower APA index compared to those prepared via as-received alumina particles.     

采用Al-Si-Ti-Cu-In钎焊70% SiC_p/Al复合材料工艺研究

采用Al-Si-Ti-Cu-In钎料在不同工艺参数下对70%SiC_p/Al复合材料进行真空钎焊,通过扫描电镜(Scanning electron microscope,SEM)、能谱分析(Energy dispersive spectrometer,EDS)技术对接头组织形貌进行分析。结果表明:采用600℃、6MPa、保温1.5 h所得接头具有最大剪切强度90.17 MPa,断裂从母材开始,穿过钎料层,在另一侧母材中瞬断,其形貌具有韧、脆混合型断口形貌特征。焊缝微观组织主要包括蜂窝状Al基体、聚积的颗粒状富Ti、In相、环状富Si相和界面处的针状Al_4C_3脆性相。提高钎焊温度有利于焊缝中孔隙的收缩和减少,增加钎料对复合材料的润湿性,也有利于激发Ti的活性,阻碍Al_4C_3脆性相的生成。由于烧结体中孔隙变化规律和柯肯达尔效应的共同作用,使得焊缝中孔隙随保温时间的延长先减少后增加,若继续延长保温时间,孔隙终将消失。提高压力能有效改善焊缝致密度,阻碍Al_4C_3脆性相的形成,并改善其形态,能有效提高接头力学性能。     

铝-钢异种金属搅拌摩擦焊研究现状及展望

搅拌摩擦焊作为一种新型的固相连接技术,具有优质、高效、节能、环境友好等优点,广泛应用于航空航天、船舶、轨道交通、汽车等工业领域。为了实现车体轻量化,铝-钢异种金属的搅拌摩擦焊研究得到越来越多的重视。从搅拌摩擦焊的工艺、组织及性能三个方面,对铝-钢异种金属搅拌摩擦焊的国内外研究现状进行综述。研究现状表明,通过控制界面金属间化合物的生成量,可得到高质量的铝-钢异种金属的搅拌摩擦对焊、搭焊及点焊接头,优化工艺参数下其拉伸性能可与母材相当,然而在铝-钢界面的精细结构表征和复杂应力状态下接头的力学性能方面还需要进一步的深入研究。此外,对未来铝-钢异种金属搅拌摩擦焊的研究方向进行展望。     

Unified Principal S-N Equation for Friction Stir Welding of 5083 and 6061 Aluminum Alloys

With the popularization of friction stir welding(FSW),5083-H321 and 6061-T6 aluminum alloy materials are widely used during the FSW process.In this study,the fatigue life of friction stir welding with two materials,i.e.,5083-H321 and 6061-T6 aluminum alloy,are studied.Fatigue tests were carried out on the base metal of these two materials as well as on the butt joints and overlapping FSW samples.The principle of the equivalent structural stress method is used to analyze the FSW test data of these two materials.The fatigue resistances of these two materials were com-pared and a unified principal S-N curve equation was fitted.Two key parameters of the unified principal S-N curve obtained by fitting,Cd is 4222.5,and h is 0.2693.A new method for an FSW fatigue life assessment was developed in this study and can be used to calculate the fatigue life of different welding forms with a single S-N curve.Two main fatigue tests of bending and tension were used to verify the unified principal S-N curve equation.The results show that the fatigue life calculated by the unified mean 50％master S-N curve parameters are the closest to the fatigue test results.The reliability,practicability,and generality of the master S-N curve fitting parameters were verified using the test data.The unified principal S-N curve acquired in this study can not only be used in aluminum alloy materials but can also be applied to other materials.